Gauge cluster/Dome lights issue

bigalpha · Sep 15, 2009

88 MJ, 6cyl.

All the bulbs are good in the blinkers, tail, etc.

When I pull the stalk to activate the running lights or headlights, on the cluster, the RIGHT TURN INDICATOR stays lit continuously. When I active the right blinker, the gauge cluster indicator light will blink on and off as well. The front and rear blinkers still work normally.

Also, my B pillar lights and kick panel lights will always stay on with the door open. The door-peg is not jammed shut. When I push the peg in (to simulate a closed door), the lights will dim but not go off.

Is it possible these two issues are related? Where do these lights ground at? Any common failure points?

ehall · Sep 15, 2009

bigalpha said:
When I pull the stalk to activate the running lights or headlights, on the cluster, the RIGHT TURN INDICATOR stays lit continuously. When I active the right blinker, the gauge cluster indicator light will blink on and off as well. The front and rear blinkers still work normally.

blown filament in one of the exterior lights. turn on the parking lights and go look for it

Also, my B pillar lights and kick panel lights will always stay on with the door open. The door-peg is not jammed shut. When I push the peg in (to simulate a closed door), the lights will dim but not go off.

sounds like short to ground in the cabin lighting harness. the internal lights are constant power and switched ground. the jamb switches (and the headlamp switch) close the ground circuit on the harness, which then allows current to flow through the lights. if you are getting constant current you are getting constant ground. the fact that it is dim just means you have weak ground

remote possibility also that your headlight switch is flaking out and causing both problems. did they both start happening at the same time?

bigalpha · Sep 15, 2009

ehall said:
blown filament in one of the exterior lights. turn on the parking lights and go look for it

I'll double check, but I've replaced them already. Maybe it was broken already or got broken in the process of installation.

sounds like short to ground in the cabin lighting harness. the internal lights are constant power and switched ground. the jamb switches (and the headlamp switch) close the ground circuit on the harness, which then allows current to flow through the lights. if you are getting constant current you are getting constant ground. the fact that it is dim just means you have weak ground

So when you open the door, it allows the peg to push outward from the jamb which allows the ground to close and complete the circuit. So essentially, something has happened which is causing it to ground continuously?

Is there a common failure point for this harness? Where can I access it to test it?

remote possibility also that your headlight switch is flaking out and causing both problems. did they both start happening at the same time?

Not sure - it had these issues when I bought the truck. I don't have problems with anything else regarding the headlights - interior lights dim, headlights go on and off every time, etc.

bigalpha · Sep 15, 2009

I assume that the same parking lights are activated between my88 and my95?

ehall · Sep 15, 2009

So when you open the door, it allows the peg to push outward from the jamb which allows the ground to close and complete the circuit. So essentially, something has happened which is causing it to ground continuously?

Is there a common failure point for this harness? Where can I access it to test it?

when one of the jamb switches extend then you get full ground, yes. it should be the same behavior for all of the jamb switches and the headlamp switch too (if not then you may have isolated teh problem). most likely there is a nick in the cabin lighting ground harness somewhere that is just barely touching the body. On my 91 the cabin lighting ground wires are solid yellow and run to all of the door jambs, all of the interior lights, and the headlamp switch too.

ehall · Sep 15, 2009

bigalpha said:
I assume that the same parking lights are activated between my88 and my95?

I don't know. I know they changed some of the signal wiring a couple of times but I don't know when.

On my 91 it turns on the front corner lights as well the lights under the headlamps (four total), and of course the lights in the tail housings also come on.

You may have a wiring fault instead of a filament fault.

bigalpha · Sep 15, 2009

ehall said:
when one of the jamb switches extend then you get full ground, yes. it should be the same behavior for all of the jamb switches and the headlamp switch too (if not then you may have isolated teh problem). most likely there is a nick in the cabin lighting ground harness somewhere that is just barely touching the body. On my 91 the cabin lighting ground wires are solid yellow and run to all of the door jambs, all of the interior lights, and the headlamp switch too.

Thanks. So, a yellow wire. Will I need to remove the inside kick panel to access the harness?

ehall · Sep 15, 2009

I don't know specifics about the 88 MJ wiring just telling you how it is on my 91 XJ hopefully it is close to the same

bigalpha · Sep 15, 2009

Well, I think they'll be pretty much the same.

bigalpha · Sep 15, 2009

Alright, did some prelim. testing.

The passenger side b-pillar dome light is the one with the bad ground. I tested both of the 'constant' and 'switched' terminals and they both tested 12V. At least I've narrowed it down to one side of the truck.

As far as the socket. I replaced the bulb with two new ones and no dice. Tested the outlet and it only shows about 9.5V with the lights on. What would cause a low voltage?

The printout from Advance shows a suspect 11.18A drain on the system. Maybe this is partly the cause.

alfman · Sep 16, 2009

The turn signal indicator on in the dash will most likely be a bad ground in the socket on the front turn signal / marker light. On my 87 & 90 XJ I ran a piece of wire from the ground tab in the socket to a metal ground in the front fender, no more problem. This problem is usually in the socket itself, socket shows no sign of a problem, but the ground is no good. This causes a backfeed through the turn signal filiment when the marker lights are turned on.

bigalpha · Sep 16, 2009

Hmmm. Should I test the resistance of the ground to the batt neg. terminal and see if it shows less than 1 ohm?

I have already replaced my other socket because the grounding tab had rusted away.

ehall · Sep 16, 2009

the running lights are switched power with constant ground (exact opposite of the cabin lights), so you should have continuity with body ground and battery negative all the time

you can test ground at the socket by peeling back a little fleck of insulation on the pigtail wires and checking resistance between there and the socket, and then isolate the pigtail by checking resistance between the fleck and chassis/battery

the same tests can be done for power but the switch has to be on

bigalpha · Sep 16, 2009

ehall said:
the running lights are switched power with constant ground (exact opposite of the cabin lights), so you should have continuity with body ground and battery negative all the time

This means that the resistance should show pretty close to Zero (0), right?

you can test ground at the socket by peeling back a little fleck of insulation on the pigtail wires and checking resistance between there and the socket, and then isolate the pigtail by checking resistance between the fleck and chassis/battery

As above, between pigtail wires and socket should show close to zero and pigtail wires and battery should show close to zero?

the same tests can be done for power but the switch has to be on

Test and make sure that 12V are making it to the pigtail wires; and test and make sure 12V is making it to the socket?

ehall · Sep 16, 2009

A simple resistance test should be close to zero but it won't be absolute zero. You can test resistance on the positive wire in the same way as ground, just remember that the switch has to be on for continuity between the pigtail and the positive battery post (external lights are switched power)

You can certainly check voltage levels at different points as well but resistance tests will give you a sharper view of the loss

bigalpha · Sep 16, 2009

Ah, I didn't know you could test the resistance of a line that had voltage going through it. I'll test that one for continuity as well.

Thanks for the assistance. I'll try to get to it tonight barring rain, etc.

ehall · Sep 16, 2009

there is a chance of frying the multimeter. you can disconnect the negative cable when you test the positive wires if it makes you feel better

bigalpha · Sep 16, 2009

Alright, thanks. I appreciate the help and guidance.

bigalpha · Sep 16, 2009

Alright, did some more testing:

Tested the ground tab on the socket against the battery ground. Came up "OL" which indicates an open circuit.

I then tested the metal prong on the wire that goes into the socket against the battery ground and came up with .1ohms.

I then tested the bare wire (made a notch in the insulation) against the battery ground and it came up .1 ohm.

So it seems the socket needs replacing. What's the easiest way to do this?

When I replaced the other side, I didn't want to try to splice new wiring on, so I cut the socket off with a dremel. Talk about a major PITA.

ehall · Sep 17, 2009

grab another pigtail at the junkyard and solder/heatshrink it on?

Gauge cluster/Dome lights issue

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