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another light question


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I've checked and replaced correct fuses from my donor xj. Didn't do the trick.

 

I'll turn the headlights on and the parking and turn signal lights come on solid. When I pull the turn signal swtich, theres no sound or lights that show up on the cluster. Also no 4 ways either. What's the best way to trouble shoot these problems?

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From the factory wiring manual with a Ground Distribution page in it regarding lighting:

 

There are 2 points on the left inner fender.

 

There is the engine dipstick tube stud. SUPER IMPORTANT!!

 

There is the ground above the lower diagonal dash brace to the left of the steering column on the shiny part of the dash.

 

There is one in behind the trim panel where the spare tire mounts.

 

The one on the instrument panel grounds a ton of things. Probably too many things as a matter of fact, given it's poor mounting point on the panel with a self tapping screw. I remove the screw that it's held on with, add a wire, using 10 gauge, and terminate it to the stud near the fusebox.

 

There are also grounds from the engine to chassis, notably the poor one from the back of the head to the firewall but that wouldn't affect your dash lights. Not that the engine to chassis grounding shouldn't be addressed.

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I've checked and replaced correct fuses from my donor xj. Didn't do the trick.

 

I'll turn the headlights on and the parking and turn signal lights come on solid. When I pull the turn signal swtich, theres no sound or lights that show up on the cluster. Also no 4 ways either. What's the best way to trouble shoot these problems?

Check your headlight grounds. My guess is that the headlights are grounding back through the parking lights.

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The one on the instrument panel grounds a ton of things. Probably too many things as a matter of fact, given it's poor mounting point on the panel with a self tapping screw. I remove the screw that it's held on with, add a wire, using 10 gauge, and terminate it to the stud near the fusebox.

 

:agree: Excellent point, it is a poor mounting point. This ground point is where the dash volt meter senses it's ground, at least on the HOs. After replacing the alt with a 134A unit and upgrading the mains cables, the VM always showed a slightly negative indication under full load, H4 headlamps, fog lamps, full blower, A/C, etc. no matter what the RPM was. I ran an additional 10AWG wire from the screw to the chassis ground on the PDC and all was well.

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Ok so I did the cluster swap from dummy lights to gauges. After doing the swap, I noticed that now when I hit the brake pedal the cluster lights light up with them. And in the middle of the swap somehow my passenger side blinker started working, now nothing. :hmm: I'm going to guess it could be the ground that's in the brace next to the colum. :wall:

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Ok so I did the cluster swap from dummy lights to gauges. After doing the swap, I noticed that now when I hit the brake pedal the cluster lights light up with them. And in the middle of the swap somehow my passenger side blinker started working, now nothing. :hmm: I'm going to guess it could be the ground that's in the brace next to the colum. :wall:

 

Do that, but don't forget the ground points on the driver's side inner fender.

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Forgot I wrote this. It addresses the poor instrument panel ground.

 

Improving the Instrument Panel Ground

 

The ground point for the complete instrument cluster on your XJ or MJ is located up under the driver’s side dash. If you lay on your back and look up under there with a flashlight, without wearing a hat, you will see a black wire attached to a shiny piece of metal almost directly above the hood release knob. The screw will have either a ¼” or 5/16” head on it.

 

This ground point is responsible for handling the ground circuit for the following items: Dome lamps, Seatbelt and key warning, trans comfort switch, wiper switch, headlamp switch and delay module, fog lamp switch, cargo lamp switch, all instrument panel grounds and illumination, power windows and door locks, cruise control dump valve, and a few more things.

 

The problem is that where the ground point is located does not have a good contact with the chassis where the ground should be. The solution is simple.

 

Make up a jumper wire with #10 gauge wire about 10” long. On one end, crimp on a ¼” round wire terminal. On the other end, crimp on a 3/8” round wire terminal.

 

Remove the screw from the existing ground wire and attach the small terminal of your jumper so that the original wire and your new jumper share the same attaching point, one over the other.

 

Look above the driver’s side plastic kick panel just forward of the top of the hood release knob. You will see an 8mm stud there. Attach the large terminal end there with a washer and nut over it tightened securely.

 

**Special note for Comanche owners: Make your jumper wire 12” long and attach it on the driver’s side kick panel close to the fusebox on the 8mm stud.**

 

 

Revised 11-29-2011

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Here is my brake light problem.

 

My turn signals work, both R and L, my flashers work. All front and rear.

 

Running lights work, as well.

 

My brake lights don't work. Replaced bulbs and brake light switch. Still no brake lights.

 

We should I start to diagnose?

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  • 3 weeks later...

Follow up to my brake light problem.

 

I checked the ground on the rear tail light. That was ok.

 

I traced the wires from the fuse box to the brake light switch then to where it disappears in the steering column. Traced from the tail lights back the other direction.

 

I deternined it was the turn signal switch. Bought one at PepBoys. Just replaced it. NOW I HAVE BRAKE LIGHTS!!!

 

This forum is great to help diagnose and fix my issues.

 

Now I want to get my Comanche restored.

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