Hello All!

Making a post to get some ideas on how to trouble shoot an issue I am having with my 1979 L82 4MT

The issue is:
- Lost all gauges including center stack except for speedo (mechanical)
- Courtesy lights and cigar lighter were working but after I pressed the lighter down it all died. Lost a bunch of other stuff too like back up lights, turn signals, and rear defrost.

What changed since the last time I remember it working:
- Replaced starter
- Replaced tach and speedo bulbs with LED
- Tried replacing center stack bulbs with LED but after trying to remove the center gauges decided to slap it back together in the interest of not breaking anything since it was getting hung up on the dash pieces on the left and right even with the screws removed.

I am troubleshooting using the diagram below and just working down the wiring:

Diagram I am using that I found on the forum

Some basic checks I did:
- The battery still has enough juice to turn over the motor and car still runs same as before.
- Pulled basically every fuse in the fuse box and inspected + measured continuity, all seemed okay.
- The generator light does not turn on, I read somewhere that if it does not turn on its a power issue and if it does turn on then probably a grounding issue
- Gauges are also completely non responsive, again read that if its grounding out somewhere some or all the gauges would plummet to zero, but if they don't move at all then its a loss of power issue
- None of the lights in center stack work (seat belt, fuel level, generator etc.)
- Power windows, radio, headlights (high,lo and high beam indicator in gauge cluster), taillights and gauge cluster lights still work
- wiper motor still works

So now I've been going around basically measuring resistance between the positive battery strap (with the battery disconnected) and various points along the wiring with the idea that wherever the resistance drastically increases indicates a break in the circuit or a short. I started at the battery post on the starter and have been working down the chain.

What I noticed so far is:

These two terminals have a really high resistance to positive (70 ish kiloOhms) and they register about 1V relative to ground when the battery is hooked up. I observed the same thing at the cigarette lighter when I put the positive lead of multimeter in the lighter to get the positive terminals value.

I also verified the 4 red wires coming from S202 (referring to the diagram above) by probing from left to right:
1. CLOCK/LIGHTER/COURTESY fuse to positive strap low resistance so I believe wire is good
2. STOP/HAZ fuse to positive strap low resistance so I believe that wire is good
3. and 4. back probed the two red wires on ignition switch to positive strap and resistance was low so I believe those are good too

I also believe the instrument panel ground (which is the ground for most if not all the failed electronics) is good since I probed the negative at the cigarette lighter to the negative battery strap and it read a low resistance.

At this point my plan is to keep going down the harness to see if I can hopefully find an obvious failure, but my main questions are:

- Does anyone know what could be causing a high impedence/low voltage at those two bat ports on the fuse box? Can you tell me which wire coming off s202 feeds them? maybe something worth checking on the firewall connector?
- Are there any other checks I can do other than probing all the wires through the system? Kindof like the generator light and gauge response checks mentioned above
- Am I right in assuming that my two fusible links at the starter are okay if I hear my high speed blower relay click on and measured good resistance between alternator positive post and starter battery post? Are there any other fusible links I should be checking on a 79?
- Does anyone know of any "commonly pinched wires" in the cluster area? I read something about the cruise control wire being a common pinch point that can cause problems

Any other advice or resources you guys can share would be greatly appreciated! I will continue to make edits with my findings

On a maybe related note, I found two connectors by the steering column area unplugged. One had a pink and purple wire coming off it and the other was green brown black. Is my understanding correct that these are for power locks and cruise control? both of which my car does not have?