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Old 03-19-2022, 04:06 PM   #1
bcoke
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Calling All Wiring Gurus

72 Blazer with all sorts of electrical issues. Trying to trace wires and get rid of all non-essential aftermarket stuff to simplify, while keeping / organizing / labeling as much of the necessary wiring I can.

Okay so this one's a doozy - weird situation, and I could use your help figuring out what's going on (pictures attached to help with clarity).

I have a Kenwood KDC-125U head unit in the dash. The wiring diagram (attached) says that the yellow wire coming out of the head unit connector is the battery wire. On the current setup, that yellow wire is connected to an orange wire (attached).

When I traced that orange wire, it first connects to my headlight switch (attached)...I have no idea why. It seems like it attached on the accessory pin, but I might be wrong about that.

And as you can see, something is wrong with the headlight switch setup because it's melted (attached) - maybe because of this?? Fingers crossed this solves it.

At the headlight switch, it's connected to another orange wire that goes to the back of the fuse box (attached). I tried to take it off, but for the life of me I couldn't get it loose. It seems like that attach point corresponds to the middle "TAIL STOP" fuse on the front (attached), but I think that's for the tail light....so I have no idea why it's connecting there.

At the back of the fuse box it links up with ANOTHER orange wire that runs to a connector with two orange wires (attached). One of those wires goes to what seems to be a housing for an under-dash light? (attached). That's at least what it seems like it could be and it was attached with a screw under the front of the dash. The other orange wire goes to a connector that hooks up to the base of the steering column along with some other connectors (attached).

Okay so does anyone know why a battery wire from the radio would be going to a headlight switch, the fuse box, an under dash light, and the steering column? Can I remove the orange wire if I'm removing the radio / speakers or does it play a critical role? The connection to the steering column has me particularly wary.
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Old 03-19-2022, 04:08 PM   #2
bcoke
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Re: Calling All Wiring Gurus

rest of the pictures
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Old 03-19-2022, 05:42 PM   #3
DeadheadNM
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Re: Calling All Wiring Gurus

Moved to the electrical section for sage advice.
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Old 03-19-2022, 05:49 PM   #4
bcoke
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Re: Calling All Wiring Gurus

Thanks!
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Old 03-19-2022, 06:50 PM   #5
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Re: Calling All Wiring Gurus

That orange wire along with the white one is the dome and courtesy light circuit. Orange being the feed, white the ground. The orange wire is always hot and goes to the brake light switch and all the bulbs. The white wire on the brake light switch goes to the turn signal switch. The other white wire on the courtesy lights goes to the headlight switch and door switches. These 2 white wires are not tied together, they are totally different circuits. Twisting the headlight switch knob activates the dome ground (white wire) and turns on the light. Opening a door switches the white wire to ground and turns on those lights.

Why the headlight plug overheated is anybody's guess.. Probably because items connected to it shouldn't be. The first sentence of your first post explains a lot of things..

The first item in your electrical toolbox should be a proper wiring diagram. If you don't have one, it's available as a free download at the top of this forum.
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Old 03-19-2022, 10:59 PM   #6
bcoke
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Re: Calling All Wiring Gurus

Quote:
Originally Posted by RustyPile View Post
That orange wire along with the white one is the dome and courtesy light circuit. Orange being the feed, white the ground. The orange wire is always hot and goes to the brake light switch and all the bulbs. The white wire on the brake light switch goes to the turn signal switch. The other white wire on the courtesy lights goes to the headlight switch and door switches. These 2 white wires are not tied together, they are totally different circuits. Twisting the headlight switch knob activates the dome ground (white wire) and turns on the light. Opening a door switches the white wire to ground and turns on those lights.
Ah had no idea that the courtesy lights and door switches were stock! That's cool - they haven't worked since I bought the truck and since the hot line from the radio was tied in, it had me thinking that everything involved was after market.

I'll save all the connectors / switches but I'd like to try to delete this for now for simplicity's sake (and because I already took out the door switches and most of the courtesy light wiring).

How would I take out the dome / courtesy light circuit without messing up the brake lights or the headlight switch?....cut the orange at the fuse box, leaving the tail that goes to the headlight switch? hmmm but that would cut the break light switch....


Quote:
Originally Posted by RustyPile View Post
The first item in your electrical toolbox should be a proper wiring diagram. If you don't have one, it's available as a free download at the top of this forum.
Thanks for the tip! I downloaded this one today from the forum (https://imgur.com/a/Yfjpeqv). Definitely helpful...I'm honestly still coming up to speed on how to make sense of it all. This exercise has helped though! Tracing orange wires all over the place
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Old 03-19-2022, 11:06 PM   #7
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Re: Calling All Wiring Gurus

Got another one for you... I found this console under the dash (pic attached) and for the life of me was trying to figure out what it did. It had a little antenna setup so I thought that maybe it was for the power locks, but after poking around on this forum, I'm pretty sure it's a remote start!

I don't have the remote to work this or have any interest in using a remote start, and this DEFINITELY is the type of complexity I'm looking to get rid of.

What're the odds I'm right about this being a remote start and any tips for removing it without messing up the manual start wiring?
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Old 03-20-2022, 11:22 AM   #8
RustyPile
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Re: Calling All Wiring Gurus

Quote:
Originally Posted by bcoke View Post
Ah had no idea that the courtesy lights and door switches were stock! That's cool - they haven't worked since I bought the truck and since the hot line from the radio was tied in, it had me thinking that everything involved was after market.

I'll save all the connectors / switches but I'd like to try to delete this for now for simplicity's sake (and because I already took out the door switches and most of the courtesy light wiring).

How would I take out the dome / courtesy light circuit without messing up the brake lights or the headlight switch?....cut the orange at the fuse box, leaving the tail that goes to the headlight switch? hmmm but that would cut the break light switch....




Thanks for the tip! I downloaded this one today from the forum (https://imgur.com/a/Yfjpeqv). Definitely helpful...I'm honestly still coming up to speed on how to make sense of it all. This exercise has helped though! Tracing orange wires all over the place
The first time you try locating the ignition switch and putting the key into it, or try hooking the seatbelt, or anything else along those lines and it's pitch black dark, you'll be wishing you had left all those interior lights hooked up and working.. If you don't want the lights working right now, why not just remove the bulbs???

That contraption you found under the seat appears to be an alarm system.. Instead of using proper splicing techniques, most of those are hacked into the factory wiring system using connectors called Scotch Locs and Stay Cons.. They ruin the wiring because they damage and cut the wires causing all sorts of gremlins and nightmares.

I was an automobile mechanic for over 30 years. Certified in many fields including electrical.. You'll not get any hacking instructions from me -- I don't know how to hack.
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Old 03-20-2022, 02:41 PM   #9
bcoke
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Re: Calling All Wiring Gurus

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Originally Posted by RustyPile View Post
The first time you try locating the ignition switch and putting the key into it, or try hooking the seatbelt, or anything else along those lines and it's pitch black dark, you'll be wishing you had left all those interior lights hooked up and working.. If you don't want the lights working right now, why not just remove the bulbs???
oh they didn't have bulbs haha it'd be nice if they worked, but since I usually don't need them (mostly drive this thing during the day), I thought it might help simplify...It seems like deleting that circuit might make things more complex, though, and I guess I should wire them back to keep it as stock as possible....I'll just have to figure out how to rewire the door switches...I'm not seeing any in this wiring diagram: https://imgur.com/a/Yfjpeqv. Am I missing it?

Quote:
Originally Posted by RustyPile View Post
That contraption you found under the seat appears to be an alarm system.. Instead of using proper splicing techniques, most of those are hacked into the factory wiring system using connectors called Scotch Locs and Stay Cons.. They ruin the wiring because they damage and cut the wires causing all sorts of gremlins and nightmares.

I was an automobile mechanic for over 30 years. Certified in many fields including electrical.. You'll not get any hacking instructions from me -- I don't know how to hack.
Yeah it looks like it's an alarm / remote start - has the exact same connectors as the one in the attached picture...I'd like to undo all the hacking and take things back to somewhat normal. Would you recommend just soldering / heat shrinking most connections or what?

Also I'd like to replace the fuse box with something modern while I'm doing this - those glass fuses are a pain to get out and I'd like extra space to put in connections down the road. Any recommendations?
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Old 03-20-2022, 03:06 PM   #10
bcoke
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Re: Calling All Wiring Gurus

Ooo just had a scary thought…the ECU wouldn’t need this to function right? The engine is an 1990 L98 TPI 350 out of a corvette or an IROC. There’s not something in the ECU that necessitates this alarm system right?
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Old 03-20-2022, 05:05 PM   #11
RustyPile
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Re: Calling All Wiring Gurus

Quote:
Originally Posted by bcoke View Post
oh they didn't have bulbs haha it'd be nice if they worked, but since I usually don't need them (mostly drive this thing during the day), I thought it might help simplify...It seems like deleting that circuit might make things more complex, though, and I guess I should wire them back to keep it as stock as possible....I'll just have to figure out how to rewire the door switches...I'm not seeing any in this wiring diagram: https://imgur.com/a/Yfjpeqv. Am I missing it?


Yeah it looks like it's an alarm / remote start - has the exact same connectors as the one in the attached picture...I'd like to undo all the hacking and take things back to somewhat normal. Would you recommend just soldering / heat shrinking most connections or what?

Also I'd like to replace the fuse box with something modern while I'm doing this - those glass fuses are a pain to get out and I'd like extra space to put in connections down the road. Any recommendations?
I described the courtesy light circuit in post #5..

As for your question concerning "something more modern"... Replace all wiring with an aftermarket system such as AAW, Painless, ect...
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Old 03-20-2022, 05:37 PM   #12
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Re: Calling All Wiring Gurus

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Ooo just had a scary thought…the ECU wouldn’t need this to function right? The engine is an 1990 L98 TPI 350 out of a corvette or an IROC. There’s not something in the ECU that necessitates this alarm system right?
I can't answer that, I'm not familiar with modern Corvette electrical systems.. Maybe some one else here or on a Corvette site can help you..
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