ELECTRIC GREMLINS: 89 Fuel Gauge and Turn Signals

[Nevada City Sparky]

I'm just about complete with my 89 XJ rebuild and have hit two gremlins that are causing me grief at the high-line instrument cluster (the one with gauges, not idiot lights). Here's the symtoms, followed by attempts to resolve:

Gremlin #1: Turn Signal Indicator
Turn Signals work fine when headlights are off. Turning on headlights causes one of the turn signal indicators to glow. Switching turn signal on, the flasher is slow. With headlights off, turn signal is fine. Removing front parking/turn signal lights makes the problem go away (but eliminates front turn signals. Whichever socket I stick the turn/park bulb into, that's the indicator that glows.

Gremlin #2: Fuel Gauge
Fuel gauge pegs at greater than 3:00 position when ignition is applied. However, the tachometer works.
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Here's what I've done electrically prior to electrical diagnosis (keep in mind this is a total vehicle restoration w/ new/rebuilt engine, tranny, rear end, transfer case, alternator, etc.):

Rebuilt underhood harnesses, soldering all splices, retaping, looking for faults, etc.

Relocated EGR solinoid and intalld aftermarket washer pumps (to relocate washer bottle for booster)

Rebuilt steering column (old one was missing parts and was funky overall)

Cleaned up loose and disconnected wires under the dash.
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Diagnosis so far:
Thinking this is a classic ground problem (thanks for the info so far on ) I started ringing out the grounds from the instrument cluster. The critical ones for this problem are in connector A (18-pin). I see two kinds of ground, one a direct ground to pin 5 and 10 tht are black, and several others jumpered together on an orange/black wire. I've traced these out and I think I have a good ground, although I get more resistance on the orange wire, which I've so far attributed to the various resistors, etc. on that circuit.

I've completely taken apart the front grill again, initially thinking I had a pinched wire. As well, I've gone through rear lights to see if I have backfeeding there.

I've also completely rung out the fuel guage circuit and it seems fine.
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Next Steps (this is wherew I need help):

Slight possiblity that my body ground is funky. I have a new strap there, but fresh paint underneath. Gonna scrape paint and cleanup.

Considering running fresh grounds to the black and orange/black wires if this doesn't work. Any problem with grounding orange/black near the cluster?

I want to drive this thing and these are the last two issues to clear up. Any help or suggested areas to check appreciated.

 

[Nevada City Sparky]

One other question:
Coming from the main bundle, which has the ignition wires, and the intermittent wiper connector, is a 3-pin connector fed by a grey, black, orange/white wire. What does this go to? Seems like it may be for an ABS light I don't have, but not sure. Speaker and courtesy light connector, which are similar two-pin connectors, are in the same area and have been accounted for.

Hoping the board can help pull me thru on this one, I've got two very long evenings shot trying to diagnose, and its my last step to getting this thing wheeling.

 

[90xj06]

it may be because it was optional. they usually have all sorts of wires laying around.

 

[Nevada City Sparky]

Anyone else <tapping foot impatiently>? Could use some *good* candidates on what the problem may be. My buddy's ready to kick me outta the garage and I gotta leave in 2 weeks for a month of business travel. In other words, as usual, I'm in over my head but willing to swim.

 

[90xj06]

check your grounds. i do not currently have my xj. but because of high resistance in a wire that is causing your slow blinker with headlights on. by removing the bulb you are lovering the resistance fixing the slow blinker.
but did you modify any thing wile you where working on you jeep?

if you want to check your ground you can do it 2 ways. 1 getting a test wire and run it from the negative terminal on the battery if that works viola you have a grounding issue. 2 checking the resistance from the battery ground to the light ground. if its more than 1 Ohm i would guess it would be that.

 

[5-90]

I don't suppose you have wiring diagrams, have you? I believe I've long since scanned copies (if you haven't,) and posted them to my RENIXPower group (groups.yahoo.com/group/RENIXPower) - let me know if you don't see them there. Once you have them, we can sit down, looking at the same pages, and see what we can see...

5-90

 

[90xj06]

also seems to be a malfunctioning multifunction switch.

 

[jneary]

did you reinstall the braided ground strap from the cylinder head to the firewall? if so is it tight?

 

[Nevada City Sparky]

I don't suppose you have wiring diagrams, have you? I believe I've long since scanned copies (if you haven't,) and posted them to my RENIXPower group (groups.yahoo.com/group/RENIXPower) - let me know if you don't see them there. Once you have them, we can sit down, looking at the same pages, and see what we can see...

5-90

Hell yes I have wiring diagrams. They have smudges and notes from one end to the other.

Here's an Update:
Cleaned up the main ground from engine block to the firewhall. It was working, but now working even better and the problem with the front parking/turnsignals got worse. Now, the front parking lights glow really dull.

I'm suspecting its a short between blue parking light wire and instrument cluster ground. Its possible I fubar'd the bulkhead connector pin, although I was pretty careful.

The ground splice in that harness has been soldered.

 

[XJING]

On my '88 if one of my turn signal indicators stays on it means that one of my driving lights is burnt out. (its even in the owners manual) hope that helps. Good Luck

 

[trintek]

i'm having the same issue with the fuel gauge, started about two days ago or so while driving back to my place.

i took the gauge out, ran a new ground wire to it and a wire from the right side connector, same issue, pegs a little past the 3 o'clock position. put everything back together and gave up on it for now.

have you had any luck with yours?

 

[Nevada City Sparky]

i'm having the same issue with the fuel gauge, started about two days ago or so while driving back to my place.

i took the gauge out, ran a new ground wire to it and a wire from the right side connector, same issue, pegs a little past the 3 o'clock position. put everything back together and gave up on it for now.

have you had any luck with yours?

Not yet. I packed it in for the weekend to do some sawmilling. I'll probably dive back into it tonight or tommorrow. Once I figure it out, I'll post here.

 

[trintek]

cool. i am going to be in the junkyard tomorrow after i pick up my bike.. may just rip the gauge cluster and gas tank off the donor jeep when i rip out the steering box and front axle.. will take me more time in the shop, but its worth a try at this point. I have to head back to san antonio in a couple of weeks and really dont feel good about using the jeep for it until i get the gas gauge working again.

 

[trintek]

Fixed the gauge problem, i regrounded the rear wiring harness, cleaned the front ground, and it started working again *shrugs* rear harnass ground is under the plastic near the drivers side tail light assembly inside the vehicle, front one is drivers side under the bottom dash panel.