C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Electrical expert help needed for my 1994

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Old 12-03-2015, 12:00 PM
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antfarmer2
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Originally Posted by crowz
What year is the car? I tried to find it in the thread but didn't see it listed.
94 in title getting old crowz?

Last edited by antfarmer2; 12-03-2015 at 12:04 PM.
Old 12-03-2015, 12:06 PM
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Bob2.0
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We've got a restoration guy here, but he's not "on call" on nights and weekends like you guys are. I do ask him stuff but I like the idea of having a record of my car repairs here for me and others to look at when they are in a jam.
Old 12-03-2015, 12:07 PM
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Originally Posted by crowz
What year is the car? I tried to find it in the thread but didn't see it listed.
It's a 1994 automatic coupe.
Old 12-03-2015, 12:12 PM
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Originally Posted by desertmike1
???????

Anyhow, you have been busy researching meter's.. good for you!

You can test a grounding circuit with a meter set up for DC/volts or ohm's scale either will work just fine, with the exception that when you test a circuit with the ohm's scale, you are "Not" loading the circuit.
Thanks desertmike1. I was hoping that was the case as everyone seemed pretty positive in their videos that their way was right. I wanted to check with you just to make sure. Yeah, after researching meters last night I was testing outlets and batteries like a kid with a new toy.
Old 12-03-2015, 12:34 PM
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The thread title was long enough it was cut off on the link I clicked to get into this thread with so I didn't see the year in the thread title.

Ok Ive got all the wiring diagrams for it now.

That said it would probably be much simpler to bypass the radio first to make sure the problem is with the wiring of the radio and not something disconnected from the radio install. Pulling the quick release plug from the back of the aftermarket radio first is where I would start (almost all aftermarket radios have this).

Once the plugs undone see if the headlights still kill the climate control. If it does then the problem is how he wired it up of course but if it still knocks out the climate control then there may just be a bad connection at the back of the climate control or another spot from him moving things around to do the install.
Old 12-03-2015, 01:29 PM
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Originally Posted by crowz
The thread title was long enough it was cut off on the link I clicked to get into this thread with so I didn't see the year in the thread title.

Ok Ive got all the wiring diagrams for it now.

That said it would probably be much simpler to bypass the radio first to make sure the problem is with the wiring of the radio and not something disconnected from the radio install. Pulling the quick release plug from the back of the aftermarket radio first is where I would start (almost all aftermarket radios have this).

Once the plugs undone see if the headlights still kill the climate control. If it does then the problem is how he wired it up of course but if it still knocks out the climate control then there may just be a bad connection at the back of the climate control or another spot from him moving things around to do the install.
Thanks crowz. I appreciate you looking into this problem with me.
I already had disconnected the stereo from the back and then thought I'd go a step further and disconnect it from where the installer wired it into the existing receiver wiring (behind the passenger seat). Same problem.
About the climate control unit, a couple of weeks ago I pulled it out thinking maybe there was a problem with the connection causing all of this. As long as it was out I took it apart, and cleaned all of the contacts on the circuit board, inspected it and reinstalled it. It worked great with the lights off, but the display and button lights went out when I turned on the headlights.
Note--When I play with the dimmer (bringing it up and down), I can see the button lights on the climate control faintly come up now and then on the climate control.
Other noteworthy items: for those just joining us whatever setting I put it on before I turn on the headlights, seems to hold so the blower is doing its thing. However, if I don't have it on, it turns on by itself after I've turned on the lights.
That's about all I can think of.

Last edited by Bob2.0; 12-03-2015 at 01:31 PM.
Old 12-03-2015, 01:42 PM
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I wounder if it could be in the light switch itself?
Old 12-03-2015, 03:50 PM
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Originally Posted by antfarmer2
I wounder if it could be in the light switch itself?
I'll be sure and check that switch. I've turned it all the way off, which I thought would take it out of the equation, but I don't know much about how all of that works.
I really don't have a game plan for this other than to use the FSM to trace the wiring of the headlamps, climate control and dimmer switch to see if anything comes up visually or with the multimeter. I'll focus behind the stereo to see if the installer of the aftermarket unit didn't disturb something.
If anyone has any suggestions on a better course of action, I'm all ears.
The adventure continues...
Old 12-03-2015, 04:54 PM
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Originally Posted by antfarmer2
I wounder if it could be in the light switch itself?
Yep, or even the dimmer.. but he needs to take a step, by step approach, or the electrical trouble shooting will drive him crazy..
Old 12-04-2015, 09:59 AM
  #30  
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Originally Posted by desertmike1
Yep, or even the dimmer.. but he needs to take a step, by step approach, or the electrical trouble shooting will drive him crazy..
Your post begs the question, what is the best step by step approach?
My current plan is to spend this evening studying the FSM, looking at the schematics for the climate control, headlights and stereo, so that tomorrow I can check grounds and follow their path looking for anything unusual, checking connections and switches along the way.
Would that be your strategy? A step by step plan would be awesome.
Old 12-04-2015, 02:57 PM
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Originally Posted by Bob2.0
Your post begs the question, what is the best step by step approach?
My current plan is to spend this evening studying the FSM, looking at the schematics for the climate control, headlights and stereo, so that tomorrow I can check grounds and follow their path looking for anything unusual, checking connections and switches along the way.
Would that be your strategy? A step by step plan would be awesome.
You have a good plan. Study the "lighting" Schematics real close. Look for a common ground, power for lighting etc.
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Old 12-05-2015, 06:42 PM
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After studying multimeter operations and looking at the schematics, I found that there were two grounds shared by the climate control and lighting system--the one antfarmer2 mentioned (G201 in the FSM) and another one (S203) which the FSM says is located at the "I/P Harn, behind LH I/P approx 6.5 cm left of Light Switch Conn break out". So to get to this though apparently I need to take out the seat, the panel on the tunnel, knee bolster and etc. After doing the opti and heater core back to back, this is starting to wear me down...
Old 12-07-2015, 10:38 AM
  #33  
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Originally Posted by Bob2.0
After studying multimeter operations and looking at the schematics, I found that there were two grounds shared by the climate control and lighting system--the one antfarmer2 mentioned (G201 in the FSM) and another one (S203) which the FSM says is located at the "I/P Harn, behind LH I/P approx 6.5 cm left of Light Switch Conn break out". So to get to this though apparently I need to take out the seat, the panel on the tunnel, knee bolster and etc. After doing the opti and heater core back to back, this is starting to wear me down...
An Option you may want to conceder; Back-probe the "Ground wire/Connector" near the HVAC unit, and then "ground" the Back probe set up directly to the Bat [-] This will at least confirm, or denies the "Ground" being an issue in the first place
Old 12-07-2015, 05:06 PM
  #34  
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Originally Posted by desertmike1
An Option you may want to conceder; Back-probe the "Ground wire/Connector" near the HVAC unit, and then "ground" the Back probe set up directly to the Bat [-] This will at least confirm, or denies the "Ground" being an issue in the first place
Thanks for sticking with me on this.

I'm not sure if I can get to that ground without taking apart a lot more dash which would have to wait until Saturday, but let me ask you this...
What if I test from the black wire going into the climate control head connector itself and the Bat [-]? Wouldn't that tell me about the ground it was going to?
Also, I ran out at lunch and pulled the climate control head out (easy to do as that part of dash/trim is still out). I found a wire coming off of it that I didn't notice before, probably obscured by the electrical tape. I'll check the FSM when I get home to see what that should be going to, but thought I'd picture it here just in case anyone would know.


Last edited by Bob2.0; 12-07-2015 at 05:10 PM. Reason: picture was huge
Old 12-07-2015, 05:45 PM
  #35  
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Originally Posted by Bob2.0
Also, I ran out at lunch and pulled the climate control head out (easy to do as that part of dash/trim is still out). I found a wire coming off of it that I didn't notice before, probably obscured by the electrical tape. I'll check the FSM when I get home to see what that should be going to, but thought I'd picture it here just in case anyone would know.

What is the wire color and what is the cavity identification "NUMBER" on the connector housing? Look at 8A-202-3

Last edited by WVZR-1; 12-07-2015 at 05:49 PM.
Old 12-07-2015, 10:03 PM
  #36  
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Originally Posted by WVZR-1
What is the wire color and what is the cavity identification "NUMBER" on the connector housing? Look at 8A-202-3
Thanks! Going by the diagram, that is the grey and black wire going to the LCD display feed. What's weird is that the LCD does show numbers but doesn't light up. So I'll dig around back there and see if I can find the other end because it used to light up prior to the stereo.
I also noticed that there was a nick exposing wire on the ground. This isn't causing my problem but this combined with the broken wire says something about how gentle the installer was putting the stereo in.
More later...
Old 12-08-2015, 09:54 AM
  #37  
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Okay. I feel stupid.
I found the problem. During my initial inspection of the wiring going to the Climate Control head, everything checked out as it went into an electrical tape wrap. As I worked in that area, the gray and white wire pictured above must have worked its way out of the tape wrap, throwing up a red flag. I unwrapped the rest of the wire bundle to find the other end and saw that not only was that wire severed, but my ground wire was frayed to almost nothing, right next to the power feed which was also frayed--all in pretty much the same place making me think that they've been rubbing against something that was sawing them off. It could be that they got moved around during the stereo install in a way that finished them off, so now I feel bad about putting this on the installer.
So, thank you all for the time you spent thinking through this, going through the FSM, googling and etc. Tonight I'll get busy repairing the wires and this weekend I'll put my dash back together just in time for winter weather.
The good thing that came out of it is that I fixed my heater core and lighter, and cleaned the contacts on my Climate Control head, all while learning a lot along the way. Thanks again to everyone who helped and to the Corvette Forum itself for being there.

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Old 12-08-2015, 11:02 AM
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Good going..
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Old 12-08-2015, 11:30 AM
  #39  
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good job I knew you could do it.
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Old 12-11-2015, 12:11 PM
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With so little room to work, I've decided to solder the wires together and cover them with heat shrink tubing. Turns out that someone cut away part of a plastic brace back there and left it all jagged which is what cut into the wiring in the first place. I'll be smoothing that out for sure.
As an epilogue to this thread, I think that underscores why doing the work ourselves makes a difference. I'm not slamming mechanics or stereo installers--many take great pride in their work, but when you are working on your own ride, you'll take the extra time and go through the extra steps to make sure it's done right.
Thanks again to everyone who took the extra time to help me do this right.


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