Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

Thanks to all on this forum as I have gotten a lot out of it but am unfortunately still stumped because of my lack of knowledge/experience with auto wiring.

I have a 1970 C10 shortbed that I bought a brand new AAW harness for and have also upgraded the gauge kit (New Tach, Clock). I have installed it per instructions and all of the wires are marked making it fairly easy to tell what is what. On my first attempt to connect the battery, I burned out to wires on the printed circuit (alternator circuit, and "terminal next to battery" circuit. It was tedious but I was able to splice together the old board and the new board for a completed circuit that would fit around the tach. The issue was that the AAW diagram showed a pink IGN wire and a GROUND going to the BAT gauge but I now know that is not how these C10s are wired. :uhmk: Even though the circuit board fried, the heater, electric fan, and front and rear running lights were on in the key's OFF position.

Thanks to VetVette (who I hope doesn't chastise me too much for posting) and others on this forum, I was able to wire up the gauges correctly and the circuit board seems to be intact. However, the heater and running lights still come on after I hook up the battery (I unplugged the electric fan). After some reading I thought that one of the wires on the ignition was staying hot but I have them wired individually so I pulled them off one at a time and the heater and lights still stayed on. :( The dash lights (connected), the brake lights, and the reverse lights don't come on with their respective triggers though. Some notes below on the components:

Ignition switch and wiper switch = old
Headlight switch = new
Electric fan came with a relay mounted next to the battery that acts as a circuit breaker. Battery cable has extra wire to hook into relay.
Battery is hooked directly to starter with red harness feed and purple IGN wire
Power side of relay by the battery has been run to the BAT side of Battery gauge and spliced to number 12 wire on dash cluster plug
A/C Heater lamp did not have a specific wire so left out. Still not sure if that little lamp completes a circuit or not, would need to splice if so.
The voltage regulator has been deleted from the harness
Haven't connected courtesy ground wire (currently capped) to anything yet as I need to wire dome switches


Thanks in advance for any information.
I appreciate any help that this forum can provide. Thanks! :help:

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

That is a lot of crap to read. Here is the short version: What would cause the running lights and heater to come on with the key in the OFF position?

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

OK, so here is what I did: Either because I had it bookmarked or it automatically popped up when I popped in (kudos to the programmer if this is the case!) so I printed a few pages out and took them to the cab and hooked up the dome light. Lo and behold that worked, for the dome light. Same thing with the running lights on at all times.

After studying the diagrams and back tracking a couple of connections, I kept coming back to the brake switch (orange and white wires). Just to try everything, I switched the leads on the switch itself and put the negative lead back on. Something different! The hazards came on. Reached in and turned them off (which worked!). No running lights but the headlights still worked. Reached in and pushed the brake and sure enough, they worked. Left right turn signal do not work though (didn't before either).

So my assumption is that the brake switch is correctly wired now. Going to figure out the rest of the puzzle tomorrow. Input is welcome but I will post results tomorrow regardless.

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

Thanks to all of the contributors on this forum for their documentation and knowledge on this forum. Still getting stumped by this one and here is where I am at with it:

I came down to blowing out the 10 Amp BRK/CTSY fuse every time I pull the switch to turn on the dash lights. So, like anyone would, I searched for this problem and it brought me to this forum on this particular thread:

http://67-72chevytrucks.com/vboard/s...d.php?t=596221

This is an AAW harness similar to mine but not quite the same. However, he seems to be describing the same issue and unfortunately the thread was never solved. :( Here is a diagram of my fuse box. I've tried to make it abundantly clear which fuse is popping. :D
http://imgur.com/a/idKiJ

http://imgur.com/a/DNOWQ

Notes: This AAW harness came with 2 orange wires marked "12v fused" but on the diagram it has an orange wire for "courtesy dome feed" but no wire in the bundle is marked as such. Just a 2nd 12 fused. The dome light does work when hooked up to a 12v fused wire but if it shares power with the brake switch or the light switch, it pops the fuse shown above above when pulling the light switch to the dash/running lamp position. My harness comes with two separate wires for both sides of the brake switch. The brakes work fine when wired this way but adding the courtesy dome (which by the way is how all the diagrams I have seen says to wire it) pops the fuse marked BRK/CTSY and the dash lights don't work. I need to take a break on this as it is driving me mad.

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

Orange light switch wire (marked 12V fused) wired directly back to panel (per AAW and full C10 color diagram). Brake Switch wire (in AAW harness but not in C10 diagram) wired directly back to panel as originally done. Courtesy lamp removed completely as it does not appear to be part of the puzzle. Double checked grounds and checked to see if any wires were open. Nope. Same fuse is popping. :banghead:

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

Well this is a new first A selfie thread. :lol:


I wouldn't ever chastise anyone for posting, but I must say that your bold font is a little hard on the eyes. I see that you discard that so thanks for that.


Now I also see by your attachments that you are using the AAW fuse panel which is different than the good ole GM version. This makes for the possibility that you have mis-wired the panel. I have not had experience with this panel but I assume the harness that AAW makes is very similar to the OEM version.

If that's the case then you will have a large red feed wire from the main junction into the cab which feeds the panel, the horn relay, the ignition switch, and the headlight switch. These are the feeds for all the key off functions of the truck.
Horn, Brakes, Hazards, cigarette lighter, and headlights including dash and tail lights.

The fuse panel feed is expanded by an orange wire which feeds the headlight switch for the Tail lights and the dash lights and it feeds the stoplight switch and the dome light fuse.

I've posted it before but here it is for those who may have missed it.

Attachment 1670073

As you can see the red wires come into the cab and form a junction then each wire goes to the location I described. The key switch and the headlight switch are not shown in this diagram. I'll put it below.

The orange wire is shown at the fuse panel in the lower right corner with the dome light connector. Notice the connector also has a white(shown as black) wire which is the ground side of the dome light and it is the side of the circuit that is switched by the door switches and the headlight switch knob when rotated. Is it possible that you have connected the white wire with the orange wire which goes to the headlight switch?


Just for information this diagram shows two other sets of wires that provide power to the fuse panel for "key on" functions.

Attachment 1670077

The pink wire from the key switch which feed the ignition coil and the fuse panel for the cluster feed fuse.

Then we have the 12 gauge brown wire from the key switch accessory terminal (shown by the arrows) which feeds the wiper fuse, the heater/AC fuse, and the turn signal flasher.

Here is the other diagram showing the Key and headlight switches

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

Oh man, I've just skimmed through the post because I'm too excited! :four: Thank you VetVette! I am going to print your reply and jump back in. Getting a response directly from you gives me the confidence to solve this. I'll report back soon. :burnout:

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

Selfie thread helps me think. Many a time I have started typing and then in the middle of it, jumped up and headed back to the garage.

In answer to your question, no, the courtesy dome is wired correctly (or left out as it is now). The difference appears to be that AAW included the white wire marked "ctsy ground" specifically (just as the brake switch wires above have their own wires).

You mention the orange feed wire from the panel. I've included a shot of the AAW harness below:

http://imgur.com/a/2wMTu

The harness does not have a wire marked "ctsy dome feed" (wouldn't you want an item like this to match exactly with the chart?) but has an orange wire marked "12V Battery Fused". My guess is this is what is supposed to feed the Ctsy Dome. However, this truck has been pieced together with a Muncie 4 speed and the reverse switch is mounted on the tranny underneath the bell housing at the base of the shifter. The 12V Battery Fused wire is currently feeding the backup lamp switch which I haven't found on any of the charts, but it works with 12V fused power.

Now, in order to incorporate the dome since I have it, I have spliced it to 3 different 12V fused wires. Here were the results:

Spliced to 12V fused feed going to backup lamp switch. This allowed the dome to work until I pulled the light switch (1st position) which shorted the fuse and thus the reverse lights.

Spliced into orange "brake switch" wire (as is shown on the OEM chart). Figured this would be my best option as it was closest to the original but had the same result.

Spliced to the orange 12V fused wire that comes directly from the switch and goes back to the panel. (Looking back I wish I hadn't done this but I will try anything) and got the same result.

Currently: All 12V fused functions have their own source directly from the panel but the courtesy dome is not connected.

If you look at the AAW chart, Circuit Branch 5 is for accessories and port 102 is another 12V fused feed. This is either for the lighter or spare 12V fused power. I currently have the lighter hooked up through this connection and on the advice of a friend I have double checked and there is not a penny at the bottom. I have seen evidence of accessory and light sockets causing issues but don't know for sure if that may be the case here.

The other difference is that on the OEM chart you have the gray wire (Cluster LP.) feeding to the cluster plug and then out to the A/C heater lamp. Currently I don't have an A/C heater lamp so the gray wire on the AAW harness (branch 7 marked "dash lights" because this is the ONLY gray wire on the harness) is connected to the the cluster plug but the gray wire going out to what should be the A/C heater lamp is capped.

This is a lot of information but hopefully someone with superior knowledge can decipher this.

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

All your experiments have one thing in common. No matter which power source you use for the orange wire to feed the dome light, It gets shorted to ground through the headlight switch.

The white wire is the ground for the dome light circuit even as stated by the AAW instructions.

It appears to me that the white wire is grounding the orange wire when you pull the HL switch knob out.

With the truck battery disconnected and not power on the electrical system, check for continuity between the white and orange wires when you pull out the knob. This is without the dome light bulb inserted. The orange wire should only have continuity to the white wire when it has the dome bulb inserted. Also the white wire is only grounded when either door switch is closed or the headlight switch is rotated all the way C/W.

The battery power fuse for the orange wire is the same as the red wire in the OEM fuse panel and should not affect anything, which it isn't if the brakes are working and the brake lights fuse is not blowing. The fuse panel from AAW is just expanding the number of circuits that are fused more so than the OEM panel.

The reverse lights circuit is one of the simplest in the whole truck. You have power to the reverse lights fuse and one wire from there to the reverse light switch and the same wire goes from there to the rear end where it splits and goes to each light. When you put the transmission in reverse, it closes the switch and power goes through the wire to the reverse lights.The manual transmission uses a switch on the transmission or the gear shifter and the automatic uses the neutral start switch on the steering column. Most of the GM vehicles use a dark green wire and a light green wire for this circuit.

I hope this helps you find the short. VV

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

Ok, "A result". Hasn't quite answered my question but we are much closer to finding the cause.

So, I took the board off the firewall and checked the back of all the lines. No burns. But it allowed me to verify where each wire should be wired to. So, after some minor rewiring, here is where we are:

Orange 12V fused wire on the headlight switch is wired directly to the block. This is at the back of the PARK LT 10 amp fuse (red) on the block. I verified this on page 3 of the AAW instructions where this wire on the switch plug is clearly marked "Fused Battery Feed (for parking lamps) from dash harness (ORANGE)". The orange "brake switch" wire is wired independently to the brake switch as originally intended by the AAW harness. The mystery 12V fused orange wire is now wired directly to the orange side of the dome light and the white ctsy ground wire is wired directly to the white wire on the dome light and the light is in the "clip".

Incidentally, I did take VV's advice and checked for continuity between the orange and white wires directly from the headlight switch since I had access to both of the bare wires. I was really really hoping it would show 0.00 ohms when I pulled the switch but no, no such luck.

So, after hooking the battery back up, I reached in and twisted the headlight knob to the left. No dome light. I would come to realize that I hadn't put the BRK/CTSY fuse back in (I only have 2 left) but that was before "the result". The dome light wasn't working because there was no fuse in place to allow it to but when I pulled the headlight switch to first position: POP A nice clear short on the fuse block popping the PARK LT 10 amp fuse.

So we are back to the orange wire coming directly from the headlight switch giving us a result. Why though is it popping fuses? And would it had made a difference if I had the BRK/CTYS 10 amp fuse in place?

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

Just a note: I realize that the issue may actually be the headlight switch even though it is new and came with the AAW harness. I suppose I can open it up and take a look but I'd hate to break the damn thing even if it doesn't work right. :confused:

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

Ok, forgive me if this is just review of the above but I'm not a professional and this is my first auto wiring job. I've done residential and know how to check for volts and continuity with a multi-meter but that's about it. Just very very persistent.

I am pretty convinced I have it wired correctly. I redid the ground on the front end so that there is no doubt the grounding is good. Pulled the switch and the PARK LT fuse popped (as expected) so we can pretty much verify the orange wire, or something it is connected to is causing the issue.

Since I had the block off of the firewall, I decided to do a continuity test on the back of the block with the orange wire socket and all of the wires from the block leading out. This probably doesn't surprise an expert but there was some resistance on all wires except for the two gray wires coming out of the bottom of the block which are for the dash lights.

One wire goes out to the cluster plug and one runs directly back to the headlight switch. The cluster plug is the old plug that I spliced into the harness and the dash is where I have the questionable circuit board. Bottom line is tomorrow I will be taking the dash off (again) and checking for shorts back there. At least I have a direction.

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

Well if you have a short to ground in the circuit board you would certainly pop the PNL LTS fuse when you turned on the headlights. The pnl lts fuse for the dash lights gets its power from the orange wire on the headlight switch after it goes through the rheostat (dimmer) in the switch, via a green wire back to the fuse panel.

When a harness comes with a new fuse panel where different fuses may split circuits, it becomes harder to isolate exactly which fuses are fusing which circuits. it makes it much harder for anyone (me) without hands on, to isolate the short. I guess what I'm saying is that your courtesy dome fuse must be fusing the dash lights, from your details, and I don't remember reading about a problem in the circuit board. That would have been a big clue but it still wouldn't explain why the Pnl Lts fuse wasn't blowing first, unless like I said, maybe they don't use it and are using the Courtesy lights fuse.

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

Thanks VV. I really appreciate your comments and thoughts and understand that doing a "hands off" diagnosis is less than desirable.

Quote from first full paragraph on first post: "On my first attempt to connect the battery, I burned out to (TWO, oops) wires on the printed circuit (alternator circuit, and "terminal next to battery" circuit. It was tedious but I was able to splice together the old board and the new board for a completed circuit that would fit around the tach. "

So in essence I have stitched together the circuit board and it maybe worth mentioning that I have LED lights in the dash instead of the standard bulbs it originally came with.

At one point in the thread it seemed to be the BRK/CTSY fuse causing the issue. Also at one point when I had it wired incorrectly (don't remember the exact configuration) It did blow both the PARK LT and the BRK/CTSY fuse but now that I am certain the wires are running to the correct places, it is definitely the PARK LT fuse that is consistently blowing.

Even with my inexperience this seems to be leading back to the dash and since VV seems to concur, that's where I will be searching today. I'll let you know what I find.

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

My "try it" method:

http://imgur.com/a/Fxtbh

http://imgur.com/a/t1q1q

The blue board is the original board I bought with the truck. The bottom two tabs on the original circuit (2nd picture) were missing so I can't even verify it worked in the first place.

This would be an obvious place for it to be grounding so I'll have to remove the dash...again. Hopefully 3rd time is the charm. :m6:

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

Finally got behind the dash. Found two things. An open ground wire which could have been affecting all of the dash wiring, or the more likely culprit of my patchwork circuit board which I have tested and have not been able to get to work properly no matter how much surgery I perform. I'm ordering a new circuit board and will post results.

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

I had a similar issue and found the harness to the turn signal switch rubbing against the steering column...

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

Thanks Yotapane. I will look there too. Those wires that run up the steering column are original and although I've looked them over once or twice, I will go over them very very carefully one more time.

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

I got a new job so have been away. Some things have changed but the results are the same: The PARK LT fuse blows every time I pull the light switch to first position.

I have gone through the switch and as far as I can tell it is functioning properly. The orange Fused Battery Feed wire is on the circuit that keeps blowing. On the other side of the fuse is a red jumper wire that jumps down to one side of the LIGHTER fuse and the other side of that fuse runs out to the Accessory Feed Wires connector that control various accessories (pwr windows, locks, etc.) I found that I had the lighter incorrectly connected to what was supposed to power the pwr windows. I hoped beyond hope that this was the problem, but no.

I received a new circuit board, verified all connections, looked over all wires and checked all connections front and back. I don't know wtf to do now.

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

Retraced wires for the back end of the vehicle and verified some connections on the front. Unable to find any short/damage/exposed wires. Still popping the same fuse but I have a question: On each side of the front end of the truck, under each wheel well is some type of electrical junction. They both have a single wire coming out of them and I am assuming these are the fusible links to hook up the Battery/Voltage gauge. Is this correct or do they need to be wired in a particular way in order for everything to work correctly?

Some success...
 

Well, some success. After pouring over schematics and different connectors, I found that I had the Park Lights wire connected to the turn signal side of the front marker/turn lights and this was grounding the wire out at the light(s). I reversed this and rewired so the side marker lights are on the brown Park Lights wire as they were wired to turn signal connections. I have read that I could throw a wire from the signal side of the front marker/turn to the side park lights and then they would be both "on" and signal. Although this is what I want, I am concerned it would just ground the Park Lights wire again. For now, I have wired the side markers to the brown wire so that they are Park Lights only, and reversed the wiring on the front marker/turn, then hooked the battery back up.

Tested the dome light which worked as expected. Pulled the switch to first position and the fuse held!!! :metal: The side markers came on and the headlights worked (they always have though). But my dash lights don't seem to want to light. Now, in testing other circuits, I turned the key to first position and tried the left turn signal. Nothing. Then I tried the right signal. Nothing...POP! Turn signal fuse blows. I have been through the switch and I believe it might actually be the original switch that was installed on the truck. It's kind of gummy on the inside and the straight springs like to pop out. I'm going to find a new turn signal switch and move forward and also research why my dash lights don't want to light.

Idiot Alert!
 

:dum: Gee C10CG, I sure would like to see those dash lights light up. Maybe because they're LED and should give a cool glow to the dash. Did you hook up the dash lights after you took them off the circuit? :hmm:

So guess what? I have dash lights. A couple or a few don't seem to be working but that is most likely from improper wiring and not running through the circuit board correctly. Fortunately I haven't fried any more boards.

I would love some direction or confirmation on how the "Battery" or voltage gauge should be wired as I believe this is one of the dash lights that is not working. I have one side wired to the alternator and one side to 12V power but they are not run through the junction boxes under the wheel wells. Are these necessary for resistance or something similar?

Thanks.

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

OK, dash lights and park lights appear to be working. I ordered a new turn signal switch and installed it. Also, I added the little light for the heater control. I hooked up the battery and once the ground cable hit the terminal: zzzz-pop....pop. OK, more fuses blown.
So now when hooking up the battery the HAZARD (15a) and the P WINDOWS (30a) fuse are blowing immediately. They are on the same circuit so it makes sense but what would cause these wires to draw too much current?

A little more progress
 

Ok, so after double checking the circuit, I found I did not have the clock wired. I wired this up and it appears to work but when the battery is grounded, the HZRD fuse blows right away. PWDOWS seems to be holding for now.

Another update...
 

So the hazard fuse was blowing because I had the knob pushed in so the hazards were "on". I pulled out the knob to turn the hazards "off", reconnected the battery and the hazard fuse held. I turned the key to the first position to test the turn signal and when I pushed up on the lever for a right turn signal, the Turn Signal fuse popped. I checked both flashers and I think they're ok but I'm not sure. Going to start tracing wires again.

Re: Another update...
 

Your hazard fuse was blowing because the short in the right turn light wiring was connected through the hazard lights when it was pushed in.
Pull the steering column plug and check the purple wire for continuity to ground
zero ohms. key off, you don't want power on these wires.

You probably won't see zero ohms there.

Now check it on the steering column side between purple and ground or what ever color matches the purple wire from the fuse panel.

First with the signal lever in no turn and then in right and left turn.
You shouldn't see zero ohms in either position unless the short is in the wiring in the column. This check isolates the steering column harness from the rest of the truck.

If you don't see zero ohms then check the right turn wire in the harness to the right turn lights. You will probably get zero ohms which means the right turn light wires or one of the lights is shorted to ground. This includes the signal indicator lights in the dash.
If you can get to it I would unplug the cluster plug to isolate the indicator lights if you get zero ohms on the right turn light wire.

The right turn light wire for the rear is dark green and for the front and the indicator it is dark blue.

Thanks again VV!
 

Thanks VV,

Well, a major part of my problem is that my rear lights were not properly grounded. I have running lights all the way around, brake lights and I'm 99.9% sure my reverse lights work. I have installed a new turn signal switch but now when I push the lever left or right, no turn signals. I switched the flashers in the block and got the same result. What I did not do is push the lever one way or another and leave it there which I tried when the fuse was blowing. Now that the rear lights are grounded, I am just pushing the lever left or right, counting to 1, and putting it back to "neutral". The good news is that no fuse is popping. The bad news is that my signals aren't signalling.

I will also run your tests above. Hopefully I didn't blow something on this new switch...

Ran those tests
 

So I checked the purple wire (Marked as Turn Switch Feed on AAW) and VV is correct. I read 0.84 ohms which is probably normal.

When I flip the switch is when everything goes to crap. Now maybe I should mention that I have been testing with the switch in the column and the steering wheel completely off and when running these ohm tests I've taken the switch out of the column and verified that no wires are touching or frayed. But I am testing with the switch outside of the column.

When I move the switch right or left, ALL of the turn signal wires, both right and left, front and back, go to 0 ohms. That certainly doesn't sound right...

Re: Ran those tests
 

Check your hazard switch for closed, this would connect all the turn wires together and give you zero ohms between the purple wire and any of the turn signal wires.

Piecing the puzzle together
 

My inexperience will probably show here so bear with me...

Here are the results with the new switch and both positions of the HAZARD knob:

A) Hazard knob pulled all the way out - No fuses pop but no signal lights at all when switch is pushed left or right. All other light functions seem to work.
B) Hazard knob pushed in - Hook the negative cable back up and HZRD fuse blows immediately

I feel like this should tell me what or where the problem lies but like I said, this is my first time wiring a vehicle and I'm learning as I go. Help me VV-wan-kenobi, you're my only hope.

Confused
 

Ok VV,

I ran your tests.
"Now check it on the steering column side between purple and ground or what ever color matches the purple wire from the fuse panel.

First with the signal lever in no turn and then in right and left turn.
You shouldn't see zero ohms in either position unless the short is in the wiring in the column. "

Well I did check the purple wire on both sides and I am getting 0 ohms on both sides. But checking the individual right/left wires, they are getting continuity correctly. So shouldn't the purple wire show continuity (0 ohms) since the electrons should be flowing to the respective wires? Confused.

Re: Piecing the puzzle together
 

Ok lets check out the new switch just to be sure. I take it that the hazard switch has to be pushed in to flash all the lights and out for the normal turn signals.

If you have the TS switch back in or still out doesn't matter as long as you know what wires are for which lights. I think you know the purple wire is the power wire for the normal turn signals and the dash indicator lights.

I'm going to use the normal colors for this test so I hope your column wires match.

Start out by removing the battery negative cable and if you have the column harness disconnected you can leave it on.

Here are the colors and what they do. Starting on one end and going across.

Black--------Horn

light blue---------left front--left indicator

dark blue--------right front--right indicator

brown----hazard power from the fuse panel hazard flasher

purple----- from fuse panel flasher for normal turn lights

yellow--------left rear turn/stop light

dark green -------right rear turn/stop light

white-----L and R rear brake lights

Here's a pic and it looks like the right colors are in the left hand. If they go to the TS switch it's all good if yours are not the same then you'll have to match them up.

Anyways here's how to test.

with the red meter lead on the white wire and the black lead touching the yellow then dark green and the switch lever in neutral-----zero ohms
these are the brake lights.

Now--put the lever in right turn and test the dark green wire---No ohms
Now --put the lever in left turn and test the yellow wire-- no ohms

if you get those readings your brake circuit is good.

Now--place the red meter lead on the purple wire and the black lead on the dark green wire with the lever in neutral--- no ohms

Now place the lever in right turn---- zero ohms--- right turn is good.

Now with the red led on purple wire, place the black lead on the yellow wire.
with the lever in neutral ---- no reading

Now place the lever in left turn ---zero ohms --left turn is good.

Now with the red lead still on purple, place the black lead on the light blue wire ( second from the end next to the black wire) with the lever in neutral--
no reading. Now place the lever in left turn-- zero ohms= the left front is good.

Now with the red lead still on purple place the black lead on the dark blue wire with the lever in neutral--no reading--lever in right turn--zero ohms. the front signals are good. Remember this is just the TS switch it doesn't mean the signal lights are good.

Now place the read lead on the brown wire (hazard) and with the TS lever in neutral and the hazard switch out, touch the black lead on the four turn wires
Yellow, dark green, Light blue, and dark blue.---no reading.

Just for kicks touch the red meter lead to the yellow wire and the black meter lead to the other three wires, Lb DB and dark green just to see if they are shorted to each other in the TS switch.

OK now we check the TS switch with the Hazard switch pushed in. The lever should be in neutral. Some of these switches are set up to flash all four lights and some of them require the lever to be place in L or R turn for the hazards to all flash. I don't remember if ours does but all four wires should read zero ohms in one position or the other.

So check for zero ohms between the brown wire and the four signal wires
Y DG LB and DB

If you are not getting these readings then you TS switch is bad.

From what you posted, with the hazard switch pulled out (off) the turn signals don't work, but if you are blowing fuses then you might not know.

I have a sneaking suspicion that your shorting blown fuse problem are a result of some thing shorted in the dash cluster indicator lights. That is why I asked you to disconnect the dash plug in my earlier post.

If you followed my testing in the other post on the turn signal wires you should have found the wire with the least ohms to ground which would indicate a short to ground and blown fuses.

GOOD LUCK.


Attachment 1685262

Re: Confused
 

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Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

I have checked the switch as requested and just so you know, yes the colors all match on my harness so everything you say makes sense. If I don't quote something from your instructions it means that it worked. I did have some variations though. Here are the results:

Red meter lead on purple wire and black lead on dark green with switch in neutral. Supposed to be no ohms. --- I am using the 20k setting on ohms and coming up 0.85 ohms. Not sure if this is close enough to zero or if it is an issue.

Red lead on purple, black lead on yellow with switch in neutral. Supposed to be no reading -- I am getting 0.84 or 0.85 ohms.

Red lead on brown, TS in neutral, hazard out. Touch black lead to the four turn wires. Supposed to be no reading. -- I am getting .04 ohms on each wire.

Just for kicks: Red lead to yellow wire and black lead to the other three wires (DB, LB, DG). This was done bypassing the switch and tested where the harness connects to the TS coupling LB and DB had no reading, but DG shows continuity (0 ohms). I believe this is a problem.

I have traced back the yellow and green wires from the harness back to where they split right and left and I can see no place these wires are touching each other. How else could they show 0 ohms?

Side note: I had printed out some test instruction that I could have sworn were from VV but looking back on this thread it must be another 68 -72 C10 forum post. Here are the two tests I ran and the results were the same:

With the switch disconnected and the battery connected, jump the purple wire and the yellow and light blue (2nd test was purple jumpered to DG and DB) and turn the key on. The left/right marker and indicator lights should blink.
Nope. The Turn signal fuse popped both times I tried this.

Incidentally, all of the tests I ran on the TS switch for left and right turn seem to work according to the multi-meter. I don't think it's the switch. Something more difficult....of course. :waah:

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

My apologies VV. You have asked me this twice now. All of the tests run above are with the dash cluster plug unplugged But just so you know I bought a new pigtail and bulb for the heater control (gray wire out from the cluster plug) and even when the cluster is plugged in the bulb doesn't want to light.

One (3) more thing(s)
 

Since we are talking about the purple and brown wire on the steering column, I thought I might mention the flashers. They are the same and came with the wiring kit. Model is 552/536 12 volt 32CP-MAX6. Since the hazard and turn are the same, it may say something about the wiring configuration but I'm not sure what.

Also, just FYI, when everything is hooked up and I try the switch in either direction, there may be a one second delay and then the fuse pops. But the lights do not flash before the fuse pops. Could that indicate the issue is before or after the flashers?

One more thing: My rear markers are 3 wire (white, red, black) LED. I have done research on these and everything I have read indicates white=ground, red=turn, black=running. I had a theory that I might have this backwards and it was overloading the switch. But this theory fails because the running lights work all the way around the truck.

Anyway, there's more info. All input is welcome as usual. :burnout:

Stumped again
 

Now I have tried isolating the front and rear lights to see if one or the other maybe causing the issue. No luck on either one. The one good piece of news is I did get my heater lamp bulb working, just needed to be grounded properly.

The only think I haven't tried for this issue is replacing the flashers. I don't know if it will do anything but these are the only part of the circuit that I can't tell for sure is bad or not. I've been reading a little bit about using LED with standard bulbs which can cause problems but the running lights appear to work fine on my LEDs.

If I was to get a flasher I was looking at this one as it's designed to anticipate issues: https://www.octanelighting.com/Chevr...yABEgJUTPD_BwE Kind of expensive though. I'll take any advice right now. This is driving me crazy.

Not the flashers
 

Got a couple of heavy duty flashers and tried them out. Same thing. Tried harder to flash this time but turn signal blew and when I switched to hazard that one blew too. I'm calling AAW on Tuesday.

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

Phew! I'm exhausted just reading your rewire experience. I just bought the "classic" kit from AAW and plan to start my project shortly. I have to admit, reading your posts has made me a little reluctant to say the least! I did want to tell you I called AAW with a number of questions I had in prepping for my project. Wow, what an awesome experience. The rep spent an hour and a half and was extremely knowledgeable about my c10. Hoping for a great outcome!

Re: Rewired 70 C10 heater and running lights on even if ign is not plugged in.
 

Thanks OUbesto,

I have talked to AAW once and the gentleman I talked to steered me in a direction which allowed me to figure out a few things on the harness. The thing that is stumping me right now are the turn signals. All of the other lights work and don't blow fuses. Both left and right, front and back refuse to flash and blow the turn signal fuse everytime the switch is pushed right or left and the hazard blows as soon as you push the red knob. The running lights WORK all the way around. How can the turn signals be grounding or shorting when the other wires on all of the bulbs appear to be carrying current just fine?