1963 Chevy c10 turn signal and engine wiring.

[ray_mcavoy]

That's good to hear that the '63 temp switch had the same threads to fit the '78 engine. I don't think it was very long after that (maybe '79 or '80) before they went to the smaller threads. The oil pressure switches stayed the same for a long time so you should be able to buy one for either '63 or '78 and get one that will fit.

Resistance in the wires should be very low (practically zero). In fact, you'd need a specialized meter (not just a regular multimeter) to be able to measure it accurately in the wire lengths typically used in most vehicles. However, you can use a multimeter to measure the voltage across the length of a wire while it's under load to see if it has excessive resistance that's causing voltage drop.

That engine harness you found at Classic Parts looks like it's the correct one. Although the description doesn't say anything about it being configured for HEI. So it might contain a resistance wire (designed to lower the voltage to the stock points coil) that you'd have to replace with a regular wire for HEI.

American Autowire and M&H Electric Fabricators both offer engine harnesses that are already pre-configured for HEI but I think they list for around $100 or so.

As long as the 2 wires connected to the "R" terminal on the starter solenoid still have a good connection with each other, the loose stud shouldn't be a problem. But that connection to the "R" stud isn't needed with HEI so to be on the safe side you could eliminate that connection and run the wire from the firewall connector (pink wire) directly to the "BATT" terminal on the distributor.

[1Loud63PU]

Ok great. I should be able to swap out that oil sensor in no time then.

I will measure resistance tomorrow. Last I check it was around .7 which seemed high!

Thanks for that idea! I’ll turn the key on and measure voltage.
The pink wire and violet wire should both read 12v with key on?

Ok I won’t order that harness since it needs work done to it. $100 seems steep. I’ll try to use this harness, at the very least order a new connector with empty pins which I found for $15.

So the R terminal on the starter, does nothing else than connect the pink wire to the distributor?

I remember that wire measuring a lot of resistance.
If that is the case, I will run the pink wire to the Hei distributor on the BATT plug and then the R terminal has nothing connected to it right?
Or does the pink still need to be spliced down into terminal R?

[ray_mcavoy]

Yeah, 0.7 Ohms would be quite high ... you'd need a piece of 14 gauge wire nearly 300 feet long to see that type of resistance. Although if there were any connectors in the wire you were measuring, those can add a fair amount of unwanted resistance if they're tarnished, corroded, or not fitting together as tight as they should.

Also check your meter by setting it to the resistance scale and touching the leads together to see if it reads zero. Sometimes the meter leads will add a small amount of resistance to the reading. And if the wire/terminal where you're touching the meter probes has some tarnish or corrosion that can increase the reading you see on the meter too.

The pink wire should read very close to battery voltage with the key on (should be around 12.6V for a fully charged battery). The purple wire will only have voltage when cranking the engine (and will likely be lower due to the load the starter places on the battery).

Yes, the "R" terminal on the starter solenoid is no longer needed with HEI. It was only used with the old points ignition to temporarily bypass the resistance wire for a hotter spark while cranking the engine.

So yes, just run the new wire from the pink wire on the firewall connector directly to the "BATT" plug on the HEI. The "R" terminal dosn't need anything connected to it any more.

[1Loud63PU]

The wires fused to the connector are connected with one another using crimp connectors where a wire slides into each end and then the center is crimped down.

I’m using the cheap harbor freight multi meter, I’ll re do any questionable wires.

Ok great, I will cut the 2 wires off the R terminal and forget about that.
I’ll run the pink wire straight to the BATT pin on the distributor.
Hoping the auto parts store has that connector available as mine looks pretty worse for the wear.

My main connector does look pretty tarnished, I will see if I can remove the pins and clean them up too.

[1Loud63PU]

Ok I went over the engine harness, for the third time.
I was able to remove each pin and sand it clean.
All resistance between the pins and wires now read .1-.2 or even 0.
I eliminated the resistance wire on Terminal R on the starter and that seems to have fixed all my wiring issues! Fingers crossed all is well now. Thanks so much for your help on that.
Still have some other wires to clean up but I ran out of time.
Also the dimming generator light to address.

Now I can move onto the choke. It’s on the carb and if it helps using it, I might as well have it functional.

Do I just tap into the pink wire on the engine harness and run a wire to the choke from the pink wire?

The choke also has a vacuum hose on it, if that helps.

[ray_mcavoy]

Cool! I'm glad to hear that eliminating the connection through the solenoid R terminal cured the engine running problem.

The electric choke needs to be connected to a switched power source that is only on when the engine is running. Tapping into the HEI power feed wire will accomplish that. I've read on some forums where some folks don't recommend that and suggest running a new feed wire for the electric choke back to a switched power terminal on the fuse box. But even connected there, the current drawn by both the HEI and choke is running through the same set of contacts in the ignition switch (which is typically capable of safely carrying that current). In any case, I would recommend adding a fuse to the wire that feeds the electric choke (a 10A fuse is pretty common for most electric chokes). If anything should go wrong with the electric choke, having it protected by a fuse will prevent it from shorting out the ignition circuit and killing power to the HEI, as well as protect the wire from burning up.

Does the vacuum hose go right into the choke housing itself? Or is it going to a vacuum operated pull-off that's hooked to the choke with a linkage rod? If it's going right into the choke housing itself, that could be a sign that it was originally a hot air style choke that has been converted to electric.

[1Loud63PU]

Ok so I find a fuse on the fuse block that is switched on and stays on at 12v with the key on.
I add a wire to that fuse with an inline 10amp fuse that goes to the choke.
Correct?

The choke has a linkage and that linkage moves out when the vacuum line is disconnected.
Here’s a picture of the choke and the vacuum line circled. When I searched up my carb numbers, it came back as a 1978 Cadillac carb if that helps.

My choke has no ground pin as I’ve seen in other videos of carbs. Is it self grounding?

[ray_mcavoy]

Yes, that is correct on the choke wiring. I think the fuse box in your truck will have a couple of terminals over near the left side marked "IGN UNFUSED". Check them with a voltmeter or test light to be sure, but they should provide a 12V source that switches on/off via the key. A 1/4" female quick connect terminal should plug right into them (either one should work). And put the 10A fuse on the end near where the wire plugs into the fuse box.

That vacuum line to the choke is connected to a choke pull-off. It's designed to quickly pull the choke open just a little as soon as the engine starts so you'll want to leave that hooked up even with the electric choke.

Yes, without a separate ground terminal, it's probably safe to assume your choke grounds through the metal housing / carburetor.

[1Loud63PU]

Ok thanks.

I got the choke wired up the “IGN UNFUSED” ran a wire to the choke and it was getting voltage, albeit it was about 10.5 volts reading at the choke.
Not sure if it is working properly but it’s hooked up.
After the wiring was fixed, it started up right away without the choke powered up. Still starts up right away with it connected. Should I just leave that part of the system alone now?
Here’s a pic of the choke plate position once the truck was warmed up.


Cold light also works and new oil sensor now lights up in dash. Sweet!
I cleaned up wiring, new batt terminals, secured some grounds, added a small ground cable to the frame from the NEG batt terminal, per wiring diagram. Installing a tachometer tomorrow.

Now instead of my generator light being dim, it’s fully on.
Turn signals also flash at half the speed. Hazards flash at normal speed. Battery is brand new. Bought it 2 weeks ago.

[ray_mcavoy]

The pic showing the choke plate fully open is exactly what you want to see when the engine is warmed up to operating temp. When the engine is cool, pushing the gas pedal down once should "set" the choke to the closed position. If it doesn't, it might need to be adjusted. That's done by loosening the 3 screws holding the side cover in place and rotating that cover a little. Many of them are marked "rich" and "lean" to show which way they need to be rotated for adjustment. But if the engine is starting okay when cold and dosn't have any driveability issues while it's warming up, the existing choke setting is probably okay.

For troubleshooting the charging system, does your truck have the original style externally regulated alternator? Or is it using an internally regulated alternator (like what would have come on the 78 engine)? A pic of the alternator showing the area where the wires connect would help to identify it if you are unsure.

The turn signals flashing at half speed could be due to an incorrect flasher relay. The electromechanical style flashers have a bi-metallic strip inside that heats up as current flows through it, the hot strip bends, opening the contacts. With current no longer flowing through the open contacts, the strip cools off, bends back and closes the contacts again. This process repeats over and over, causing the bulbs to flash.

The amount of current flowing through the flasher influences the flash rate. So if a flasher that is meant for the hazard lights (where it's flashing 4 bulbs together) is installed in the turn signal circuit (where it only flashes 2 bulbs), the rate will be slower.

[1Loud63PU]

I took the air filter off today and the choke was still pretty open.
I pulled the throttle but not all the way and it didn’t seat. I manually pushed the choke plate down and then it sprung back into its closed position. Guessing I didn’t move the throttle enough to reset the choke plate?
Here’s some photos of the plate after it sat all night and a photo of it once it sprung back into the closed position. How’s the closed position look?

I’ll go through a hot and cold cycle tomorrow to see if a full press of the throttle resets the choke.

I think it’s an internal regulator that it uses. Here’s a picture.

I found the reason my generator light was fully on and why the blinkers were so slow.
The wire harness under the light harness (on the driver side firewall) had a spare wire that was cut. It was cut right near a ground bolt so I figured it was a ground. So I grounded it. Turns out that wire is getting voltage somehow! I removed it from ground and the flashers are now working properly. The generator light is back to square 1. While running it is off, only when the headlights, (not the running lights) turn on, is when the gen light turns on too. It is very faint now. Before it was a bit brighter but after the new terminals and solid negative batt grounds were fixed, it’s barely visible but does get a little brighter when I give it gas.

That spare wire that I thought was a ground but actually had +voltage, I hooked it up to a spare terminal on the horn realy( I think that’s what it is) and victory!
Gen light was completely off even with headlights on.

But then I shut the truck off and the gen light was fully on.
So I removed it from the relay, back to square one again. Gen light dimly lit only with headlights on.

Here’s a photo of that spare wire while it was connected to the relay. It’s the thin black wire on the right side, just below the red wire.

I did some reading around and ran a few tests I found online.
NEG batt cable disconnected, I checked between the POS batt terminal (still connected to the truck) and the NEG cable(now disconnected) and I read .55-.64 volts. A short somewhere.
I disconnected the alternator, still read voltage. I removed fuses 1 by 1 and I was still getting voltage on the reader. I removed all fuses from wiring I added and no change. Only system I didn’t check was the radio, which I added but forgot to check until now that I think of it. Eventually the voltage started to drop till it hit 0 or close to it.
It went from.64-> .55-> .30-> .17-> .7-> .2. Around those numbers.

These are the voltage readings from the truck.
IGN off: 12.9
Engine running: 14.8
Engine running with headlights on: 14.4
Negative cable removed: .64-.2-0

Here is also a photo of a small junction type box. This box holds those wires on the spare engine bay connector we talked about earlier and some of the wires go to the alternator and 1 wire goes to the batt +.

[ray_mcavoy]

The 2nd photo of the carburetor with the choke closed looks good for where it should be when the engine is cold and you have "set" the choke by pressing and releasing the gas pedal. So you should be all set there.

I'm not seeing the pic of your alternator so I'm not sure whether you're dealing with an external or internally regulated one. But I don't see an external voltage regulator in the other pics either so there is a good chance it has been converted to internal.

Double check the color of that spare wire that you first connected to ground then moved to the screw terminal on the horn relay. It looks brown (instead of black) in the pic. And if it is brown, that's likely the wire that comes from the generator light. If that's the case, it would have originally been connected to the #4 terminal on the old external voltage regulator. And would need to be connected to the "light" terminal on the internally regulated alternator. Assuming you have a 10SI alternator (which is what likely would have been stock on the '78 engine), the brown "generator light" wire would go to the #1 terminal on the alternator's 2-wire plug.

I'm not quite sure I follow the test you did with the negative battery cable disconnected. It sounds like you are describing a parasitic drain test to check for items that are drawing power and draining the battery with the ignition off. However, that typically involves connecting the meter between the disconnected battery terminal cable and the battery terminal it was removed from. And the meter is set to measure current (amps or milliamps) instead of voltage.

The voltage readings you measured with the engine off & running look a little bit on the high side but not out of reason. Might just be the accuracy of the meter.

The junction block in the last pic looks like the style that GM originally used in the 73 to 87 trucks. It likely came from the '78 engine donor. All of the main power feed wires (from the battery, alternator, and cab) originally connected together on those 2 screw terminals on the horn relay. It looks like yours has had those wires re-located to that added junction.

[1Loud63PU]

Sorry, all those pictures, I forgot the alternator one, here it is.

Yea, I set the choke by manually moving it but I don’t think I pressed the gas down far enough to set it.
But that is good to know. I had no idea you had to reset the choke, thanks.

Good eye! I doubled checked it and yes it is a brown wire.
Would #1 terminal on the 2 pin plug on the alternator be the wire on the top(greenish/brown) or the bottom(redish) wire?

Wow, I did the test backwards now that you mention it.
The procedure I read, said to measure between the Negative post and the disconnected negative cable and I was reading from the positive post to the disconnected Negative cable.

Here’s the link where I got that test from. 4th paragraph down under “BATTERY”
http://www.type2.com/library/electrip/kuhn4.htm

The readings may be the reader. It’s a $6 one from harbor freight, so I wouldn’t say it has the best accuracy.

And yes, that new junction box is the one with all the power now. The spare 4 pin plug on the firewall(with only 2 pins in use)we talked about earlier that would kill all the power of disconnected, is wired up to that.

1 wire from the extra connector on the firewall goes to the junction box.
1 wire goes to the alternator.

From the junction box, 1 wire goes to the +battery post and 2 other wires to the alternator.

[ray_mcavoy]

Yes, that looks like a 10SI internally regulated alternator (which would be stock equipment for the '78 engine).

The #1 (indicator light) terminal on that alternator is the one toward the top. The wire from that terminal should run over to and connect to the end of that brown wire (near the horn relay) which should complete the circuit back to the generator light on the dash.

The #2 (voltage sensing) terminal on that alternator is the one toward the bottom. The wire from that terminal should run to the main power distribution junction block. And the wire from the output stud terminal on the back of the alternator should also be going to that junction block. Some folks connect the #2 terminal to the output stud with a short jumper wire. That works too, but doesn't take full advantage of the alternator's remote voltage sensing capability.

The middle part of the 4th paragraph in the link you provided is describing a parasitic draw test where you disconnect one of the battery terminals and measure between that and the battery post it was removed from. It describes using a test light (which will light up if there is a drain on the system, and vary in brightness depending on the draw). If you measure it with your multimeter, you'll want to set it on the current (not voltage) scale. For an older vehicle without modern electronics, the key off draw on the battery should be minimal ... typically under 25mA (milliamps).

[1Loud63PU]

I will remove the tape around the wires to the alternator and see where exactly they are on the junction block. But from what you’ve said and what I’ve seen on the truck, it sounds about right.

Here’s what I understand.
The bottom wire on the 2 pin connector goes to the junction block
The wire on the stud behind the alternator also goes to the junction block

The junction block when runs a power wire to the cab and another power wire to the battery right?

And the top wire on the alt 2 pin plug goes no where else except to the brown wire over on the driver side?

Hmm, yea I didn’t do the parasitic test properly then. I will do it once again when I figure all this out.

[ray_mcavoy]

Yes, that all sounds correct for the electrical connections.