Cj7 wiring problem

**Dborns** · 01-25-2010, 03:01 PM

First of all, let me say thanks to everyone that has helped me just in the last few days. My '77 Cj7 is going to need alot of work and obviously this is the place to go for help....

My next problem I am working on is a turn signal and brake light problem. When I have the headlights on, the right side f/r turn signal works, but very slowly. the left side won't work at all. If I turn the headlights off, all four turn signals work and blink at a normal rate. Also the hazard lights don't work at any time.
So far, I've checked the bulbs and fuses. I also found the ground to the dash, ground to the motor, and ground to the firewall from the negative battery terminal. The ground to the dash has a rusted screw, but seems to be contacting metal. The ground to the firewall seemed okay; the braided wire was a little rusty but I cleaned the firewall and wire and reattached. The ground to the motor seemed ok. Am I missing a ground or does anyone else have any ideas of what I can try next.

**thantos858** · 01-25-2010, 03:17 PM

Clean all the grounds. Replace any rusted screws or connectors with new ones if they don't clean up easy.

CO64CJ5 · 01-25-2010, 04:18 PM

Unless your headlights and turn signals are mounted on the dash, the firewall, or the engine, you have missed a ground.

The headlights and turn signals are grounded to the grill. Be sure your grill is grounded. The bolts which attach the grill to the rest of the vehicle are not really adequate for this -- you should run ground wires from a known good grounding point to the grill, preferably to the headlight and/or turn signal mounting bolts.

cad9176 · 01-25-2010, 04:40 PM

There are grounds on the tail light harness to frame. Check that.

**Dborns** · 01-25-2010, 07:18 PM

Thank you all for the suggestions,
CO64CJ5- Please explain how to run "ground wires from a good grounding point". I apologize, but the only auto wiring experience I have is the Haynes auto wiring book I am waiting on. Which means I don't know what I'm doing.
I contacted the seller, and he isn't sure where the wiring harness came from so that means I can't go by the '77 schematic. I have a bunch of wires under the dash that end in plastic "male" connectors, plastic "female" connectors, and inline connectors with nothing connected. So the other electrical components that coincide with these connections will have to be dealt with later.
As far as the grounds, the only ones I have found so far are the motor to frame, battery negative post to firewall, and under drivers side dash wire harness to dashboard. I did find a wire in the rear wheel well, drivers side, that is connected to the frame but is not connected to anything else. There are 3 wires coming out of the rear, drivers side light that have obviously been cut and reconnected, that go down to the pass. side rear brake light. But I still have what looks like a ground wire handing there, that I talked about above. I did buy three new screws tonight to reattach the ground wires so I will try that wednesday.
Any more ideas?
Thanks!!!

**Dborns** · 01-25-2010, 07:20 PM

And sorry, Cad9176,
Where are the grounds on the taillight harness frame that you are speaking of? Like I put in the above reply, I found a wire hanging from the body not connected to anything, but all the wires have been cut and reconnected in the drivers side rear.

**John Strenk** · 01-25-2010, 08:10 PM

I think the ground for the rear tail light is still the mounting stud. There is a ground for the Fuel level sensor and some years had a ground for the side marker light, This is the one usually found hanging around when it brakes off the light socket.

**Dborns** · 01-25-2010, 08:42 PM

Hey John,
Thanks for your time,
I haven't looked at the rear pass. side light to see if the wiring ends there, but I know that the harness connects to the drivers side rear and continues on the back bumper to the pass. side. Like I said in the previous post, at the drivers side rear light, I have three wires from the harness connecting to the three wires going to a NEW rear light. The three that come out of the harness have grey splitters on them and two of those splitters have wires coming out of them that go down the bumper to the pass. side rear light. The third splitter has a partial wire coming out of it that is cut with no connection. There is a fourth wire that just comes from the pass. side and goes up into the light. What I said looks like a ground wire is connected to a bolt on the back of the body and is about 6" long with an "o" ring on the end not connected to anything. It probably is a ground wire but there isn't any obvious connection for the "o" ring. Again, this wiring harness has been cut, splayed, and reconnected everywhere so I can't give you anymore info than that.
Thanks for your help in advance.

**Dborns** · 01-25-2010, 08:44 PM

I forgot to add,
The fuel gauge also does not work, (new tank, old sending unit), and J Strenk mentioned something about a fuel level sensor. Would a ground at the sensor be causing this?

pspradlin2 · 01-25-2010, 08:54 PM

i have an 83 that had problems with the turns signals, they would only work when pulled or pushed the lever while moving it and wouldnt work when i had the lights on sometimes. i found that the brake lights were not working with the lights on either. i replaced the turn signal switch to and it fixed all problems with lights till this last weekend when the ground wire to from the battery to the body melted this was caused by a loose bolt causing the amperage to raise.

**John Strenk** · 01-26-2010, 03:36 AM

Quote:

Originally Posted by Dborns

Hey John,
Thanks for your time,
I haven't looked at the rear pass. side light to see if the wiring ends there, but I know that the harness connects to the drivers side rear and continues on the back bumper to the pass. side. Like I said in the previous post, at the drivers side rear light, I have three wires from the harness connecting to the three wires going to a NEW rear light. The three that come out of the harness have grey splitters on them and two of those splitters have wires coming out of them that go down the bumper to the pass. side rear light. The third splitter has a partial wire coming out of it that is cut with no connection. There is a fourth wire that just comes from the pass. side and goes up into the light. What I said looks like a ground wire is connected to a bolt on the back of the body and is about 6" long with an "o" ring on the end not connected to anything. It probably is a ground wire but there isn't any obvious connection for the "o" ring. Again, this wiring harness has been cut, splayed, and reconnected everywhere so I can't give you anymore info than that.
Thanks for your help in advance.

Almost all the wiring should end on the passenger side. There will be a WHITE wire going to the side marker light on the passenger side.

The splitters sound normal.
There should be a WHITE wire that runs to Both rear lights for your normal tail lights as well as the side marker Lights.

GREEN With TRACE to Right Turn signal
GREEN TO Left Turn Signal

WHITE with TRACE goes to Backup lights Both sides

PINK to fuel sending unit.

The wire with the "O" rings could be a ground someone added to help ground the tail lights.

**Dborns** · 01-26-2010, 08:54 AM

Thanks for the schematic John. The coloring on the wires doesn't match up to any wiring harness schematic that I've looked at. I'm not sure where the harness came from or what it came off of but I would think I would be able to trace the wires back to where they come out under the dash. The way it is wired right now is:
Out of the harness there is a yellow, black, and orange wire-
yellow tied into red goes to drivers side rear light
black tied into two reds; one goes to ds rear light, the other to pass. light
orange tied into two blacks; one to ds rear light, the other to pass. light
one red from ds rear light, straight to pass. side
Thanks

**John Strenk** · 01-26-2010, 09:29 AM

Quote:

Originally Posted by Dborns

Thanks for the schematic John. The coloring on the wires doesn't match up to any wiring harness schematic that I've looked at. I'm not sure where the harness came from or what it came off of but I would think I would be able to trace the wires back to where they come out under the dash. The way it is wired right now is:
Out of the harness there is a yellow, black, and orange wire-
yellow tied into red goes to drivers side rear light
black tied into two reds; one goes to ds rear light, the other to pass. light
orange tied into two blacks; one to ds rear light, the other to pass. light
one red from ds rear light, straight to pass. side
Thanks

Hmmm... That does sound like a mess. You probably should check some YJ or TJ wiring harness schematics. See if that could be were the harness comes from. That Picture is out of the FSM and does match up on my 76 CJ as well as my Haynes manual.

That "Frame Harness Connector" in the picture above should be right at the drivers door. The wires going into it should be the stock colors. You could start checking from there.