Electrical Weirdo wiring problem

[mickey85]

Note that I'm cross-posting this from JeepForum as well...

Okay, so for a bit of backstory, I'm restoring my dad's 83 CJ7 . It still has the original computer controlled carb, still has the original ignition system, and still has mostly the original wiring harness. I had the computer and ignition harness rebuilt, as mice had eaten the wires by the ECM plug. Dad wanted the thing back as stock as possible, but he passed away, and I'm trying to honor his wishes.

I had a no-spark situation, but thought I'd remedied that when I read JeepHammer's stuff about grounding and wiring and such. I spliced a ground wire into the distributor ground wire, and got a great spark. Got the thing to run really well, but I think I may be back to no-spark. That's something to deal with later (by the time I was done today dealing with battery problems, the battery was so tired it didn't want to turn over the motor much, and it didn't make spark. I may have cooked the module, but I have a spare if so).

Here's what I've done so far:

This is the front of the driver's side fender. The purple wire grounds both sides of the headlights and marker lights. The two blues are 12 gauge. One runs to the headlight switch mounting screw (the mount that runs through the dash panel). The other runs to a small stud I have on the firewall to ground dashboard stuff.


Passenger side dedicated ground. 12 ga to battery negative, little black wire (16 ga?) to ignition ground, 12 ga to the alternator case (which is also spliced to the head)


Alternator wiring. light blue is 10ga fusible link to the battery side of the solenoid. Dark blues go from the head, to alternator, to dedicated ground. I replaced the plug, and it seems really tight...


Under dash. Blue 12ga goes to dedicated ground on the DS fender. Black to the left goes to aftermarket tach, black going up grounds a mounting stud for the speedo assembly, black to the right grounds the oil pressure gauge light.


Now, this is what's happening. When I twist the light knob (for the dimmer), the gauges and 4x4 light respond:

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And I have no idea. There isn't anything added to the harness under the dashboard, and there shouldn't be any reason why it does this. I'm also getting a clicking on the passenger side of the engine bay when I twist it counterclockwise, but have no idea what it is (I didn't have a helper with me to explore further).

Also, what the hell are these plugs? I can't find them in the wiring diagram, and Dad didn't label them. There's also a two-prong connector by the parking brake that is connected to the dimmer switch wires. Does that go to the parking brake warning light? I don't seem to have that, and can't find a replacement, so I don't know. The yellow/orange ones taped together appear to be for a dash light, but they don't seem to have a home...




Also, where do y'all plug in your tach light?

 

[Scout1067]

Those top plugs look like dashboard light plugs. If yours is like mine then the tach has a battery + to it and the rest of the dash lights feed off that and are wired into in series. That bottom plug looks like the heater switch to me.


I use a ground bus bar by the battery and run all my grounds to that instead of a couple separate grounds in different places. That fixed all my grounding issues except for my fuel gauge and I think it just hates me.

Sent from my SM-A405FN using Tapatalk

 

[caveman]

Fuel gauges are mean little buggers.

 

[RichChapin]

look at the starter cycloid the
blue wire attached to s is the starter switch from the key in start mode should be 12 volts at cycloid key in run position zero volt

red wire attached to I is 12volt when key is in start mode this feeds the engine when the jeep is in start mode,

0 volt their on I as the jeep is in start mode that would create a no spark as the engine is in start mode

start mode is when the jeep engine is turning over

make sure that its grounded

 

[mickey85]

Thanks guys, I appreciate it. I'll keep you guys updated on what the situation looks like this weekend when I get back there. That 4 wire plug runs off of the light switch. The white wire at the end runs off of the light switch, but I can't find any plug on the diagram that shows a 4 wire plug like that, nor where it goes. I can't find anything that looks like the male version of that plug either.

 

[RichChapin]

thats the fog plug
wire
18 gauge white #18A
14 gauge red w/white trace #15a
14 gauge orange #128
16 gauge gray w/white trace # 2

 

[mickey85]

So, I get it running, then it died. Discovered it was a blown ign/lps fuse. So I replaced it and started tracing wiring in the dash. The 4x4 and brake light were wired correctly. I discovered by accident that the fuel and temp gauges weren't grounded. So I grounded it and lo and behold, EVERYTHING worked perfectly!

That fixed, I went to work on the brake pedal - the spring I installed was a touch too long, and at the time, it didn't seem like a problem. So I dropped the steering column to the bottom of the dash hole to reach the spring. Took out the spring to replace it, and all of a sudden, though I touched not a single wire, I started having the same problems as before with the weird ground. Tried to run a jump wire from the temp ground post to ground, nothing.

I'll button up the steering column and start chasing again. I did notice that the ground pole on the (new) fuel gauge was loose, so perhaps that's the deal. New gauges are cheap.

Grr...