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Instrument cluster lights don't work


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Hey guys. So ive tried to figure out why my back lights on my cluster won't turn on and I'm at a stand still. Ive check continuity between the wires from fuse box to cluster and took a test light to the fuse box, checled bulbs, checked the recepticles and even fuses and I'm at a total stop. Does anyone have any suggestions on how I can drive my MJ at night lol.

 

Btw all gauges, i.e. fuel gauge, speedometer, low fuel light, battery light oil pressure, turn signal lighys and high beam lights work. Its only the connectors for the back lights.

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Obviously you've tried turning the headlight knob to un-dim them? If the switch is older, there's a good chance the rheostat coil has either developed dead spots or ceased working all together, in which case you'll have to replace the headlight switch.

If you do end up pulling the switch (or even if you don't) if the connector for it looks melted at all, you should definitely look into upgrading your headlights with a relay harness before your switch gets hot enough to set itself on fire like mine did.

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That style headlight switch is a disaster waiting to happen.

 

But that's not the only thing that will get you.  There is a rather poor ground on the cluster.  If the headlight switch isn't as awesome, combined with the less than ideal ground, it will light the bulbs so poorly that you won't know they're on.  Also, the 'circuit board' on the cluster can corrode around the contacts for the connectors and the bulb holders, this will add resistance and make it even worse.  Again, they might actually be lighting up, just so dim you can't tell.  Take everything apart and clean it first, bench test the cluster by powering the pins for the lighting, wiggle the bulb holders to make sure they have good contact, and go from there.

 

Do the relay upgrade on the headlights either way.  The stock setup is terrible.

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Obviously you've tried turning the headlight knob to un-dim them? If the switch is older, there's a good chance the rheostat coil has either developed dead spots or ceased working all together, in which case you'll have to replace the headlight switch.

If you do end up pulling the switch (or even if you don't) if the connector for it looks melted at all, you should definitely look into upgrading your headlights with a relay harness before your switch gets hot enough to set itself on fire like mine did.

I have messed with the dimmer switch because I've been told theyre a royal pita. Ill take that apart and look into getting a new one..if i can find one. Ive had a hard time finding parts.

 

As far as the headlights I have considered upgrading to newer housings with actual bulbs like I did on my TJ and my wifes Jeep.

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That style headlight switch is a disaster waiting to happen.

 

But that's not the only thing that will get you. There is a rather poor ground on the cluster. If the headlight switch isn't as awesome, combined with the less than ideal ground, it will light the bulbs so poorly that you won't know they're on. Also, the 'circuit board' on the cluster can corrode around the contacts for the connectors and the bulb holders, this will add resistance and make it even worse. Again, they might actually be lighting up, just so dim you can't tell. Take everything apart and clean it first, bench test the cluster by powering the pins for the lighting, wiggle the bulb holders to make sure they have good contact, and go from there.

 

Do the relay upgrade on the headlights either way. The stock setup is terrible.

I cleaned up a few grounds that i think are for the cluster but I'm not 100% sure theyre the right ones. I did take the cluster out and clean up the bulb receptacles along with the circuit board so they have little to no corrosion. I had the cluster plugged in all lights on and where I thought the switch needed to be in total darkness and no lights.

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Replacement bulb list

 

I just walked into random parts store, gave the drone my year, make, and model, and even up in the Great White North they had one in stock. :dunno:

But it did cost me more than $20. I'm pretty certain it's been reused in quite a few Jeeps over the years.

Edit: maybe not a bunch of Jeeps, but the Airtex switch listed on Rock Auto also lists some AMC's and a bunch of 60's and 

70's plymouths, so, um, yeah.

 

The purpose of the headlight harness upgrade isn't so much to improve lighting (but that is a happy coincidence) but rather to remove load from the headlight switch and wires. From the factory the entire load from the headlights goes through the switch, which is barely up to the task of that load. Then add years of corrosion, and the resistance in the wires increases, leading to bigger loads, and the switch can't handle it any more. All the relay harness does is add some relays to the system to pull the load off the switch. It goes between the bulbs and sockets too, using the factory wiring to trigger the relays. I need to put together another one for my XJ, when I get around to it I'll try to make a write-up this time.

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where is the ground point for the instrument cluster?  I found where I thought mine was and disconnected it, but the lights stayed on.  my lights are coming on, but are not very bright.  I thought I would try to upgrade the ground before tearing too deep into anything else.

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check all your fuses.  I learned on this forum that if your instrument illum lights do not work, they are designed that way to alert you that you have a problem in your tail lights that you can't see while driving. 

 

Mine turned out to be hacked up wiring to a trailer connector.  Straightened out the taillight wiring and the inst cluster came to life......

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You have not said what yr your MJ is, nor what it has (engine, trans, mods, etc.), so we may be guessing.

 

Based on the 88 electric FSM, the Inst cluster lights are powered by an org w/ blk wire from the light switch.  The light switch is hot all the time.

 

The Instr fuse is 5 amps (88 FSM).

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Entirely possible that your clutch master cylinder has leaked and damaged the fusebox. My 89 had it bad and the gauge cluster lights didn't work at all until I replaced the fusebox. Can you wiggle the fuses any? They should be tight. Do the little connectors in the fusebox look corroded? That's the first thing I'd check if I had electrical issues on a manual shift truck.

 

Sent from my LG-D850 using Tapatalk

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Entirely possible that your clutch master cylinder has leaked and damaged the fusebox. My 89 had it bad and the gauge cluster lights didn't work at all until I replaced the fusebox. Can you wiggle the fuses any? They should be tight. Do the little connectors in the fusebox look corroded? That's the first thing I'd check if I had electrical issues on a manual shift truck.

 

Sent from my LG-D850 using Tapatalk

 

Where did you get a new fusebox?  Or was it a junkyard pull?  Mine is destroyed (clutch master) and I would like to do something about it...

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