Plumdog Millionaire Posted December 4, 2016 Share Posted December 4, 2016 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. Link to comment Share on other sites More sharing options...
gogmorgo Posted December 4, 2016 Share Posted December 4, 2016 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. Link to comment Share on other sites More sharing options...
DirtyComanche Posted December 4, 2016 Share Posted December 4, 2016 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. Link to comment Share on other sites More sharing options...
Plumdog Millionaire Posted December 4, 2016 Author Share Posted December 4, 2016 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. Link to comment Share on other sites More sharing options...
Plumdog Millionaire Posted December 4, 2016 Author Share Posted December 4, 2016 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. Link to comment Share on other sites More sharing options...
DirtyComanche Posted December 4, 2016 Share Posted December 4, 2016 There is generic versions of that headlight switch available. Rockauto has them for about the $20 range, I believe. Link to comment Share on other sites More sharing options...
Plumdog Millionaire Posted December 4, 2016 Author Share Posted December 4, 2016 There is generic versions of that headlight switch available. Rockauto has them for about the $20 range, I believe. Is this it?http://www.rockauto.com/en/moreinfo.php?pk=43525&cc=1181472&jnid=426&jpid=1 Link to comment Share on other sites More sharing options...
DirtyComanche Posted December 4, 2016 Share Posted December 4, 2016 There is generic versions of that headlight switch available. Rockauto has them for about the $20 range, I believe. Is this it?http://www.rockauto.com/en/moreinfo.php?pk=43525&cc=1181472&jnid=426&jpid=1 Looks like the right one to me! Link to comment Share on other sites More sharing options...
Plumdog Millionaire Posted December 4, 2016 Author Share Posted December 4, 2016 Roger that. Ill order a new one and swap it out and go from there. Should probably get some new bulbs while I'm at it. 194s right? Link to comment Share on other sites More sharing options...
gogmorgo Posted December 4, 2016 Share Posted December 4, 2016 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. Link to comment Share on other sites More sharing options...
gconcilio Posted December 4, 2016 Share Posted December 4, 2016 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. Link to comment Share on other sites More sharing options...
tugalo Posted December 4, 2016 Share Posted December 4, 2016 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...... Link to comment Share on other sites More sharing options...
Plumdog Millionaire Posted December 4, 2016 Author Share Posted December 4, 2016 Update Took a test light to the 5 amp fuse for the instrument lights and I am getting nothing. Anyone know where those wires come from? Link to comment Share on other sites More sharing options...
87MJTIM Posted December 5, 2016 Share Posted December 5, 2016 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). Link to comment Share on other sites More sharing options...
Plumdog Millionaire Posted December 5, 2016 Author Share Posted December 5, 2016 Sorry. I forgot to add that last night with the original post. 87' with the 2.5L and not sure if it has the 5 speed or 4 speed. Has a 5 speed shifter knob but won't go into "5th". No mods. Link to comment Share on other sites More sharing options...
DirtyComanche Posted December 5, 2016 Share Posted December 5, 2016 If the switch is bad you may well not get power at that fuse. Link to comment Share on other sites More sharing options...
Minuit Posted December 5, 2016 Share Posted December 5, 2016 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 Link to comment Share on other sites More sharing options...
Plumdog Millionaire Posted December 6, 2016 Author Share Posted December 6, 2016 Replaced headlight switch and created a jumper for the instrument cluster lamps and it works. Barely seen it considering i knowingly had one good bulb in. The switch was corroded and barely made contact. Cleaned up the ground while i was at it. Thanks everyone who helped me narrow it down! Link to comment Share on other sites More sharing options...
Plumdog Millionaire Posted December 6, 2016 Author Share Posted December 6, 2016 Replaced headlight switch and created a jumper for the instrument cluster lamps and it works. Barely seen it considering i knowingly had one good bulb in. The switch was corroded and barely made contact. Cleaned up the ground while i was at it. Thanks everyone who helped me narrow it down! Link to comment Share on other sites More sharing options...
DirtyComanche Posted December 6, 2016 Share Posted December 6, 2016 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... Link to comment Share on other sites More sharing options...
Minuit Posted December 6, 2016 Share Posted December 6, 2016 Junkyard from an automatic XJ. I pulled it from a '90 and it was identical to the original. Sent from my LG-D850 using Tapatalk Link to comment Share on other sites More sharing options...
DirtyComanche Posted December 6, 2016 Share Posted December 6, 2016 Junkyard from an automatic XJ. I pulled it from a '90 and it was identical to the original. Sent from my LG-D850 using Tapatalk Figured as much. I might actually have one in storage. I should look for it. Link to comment Share on other sites More sharing options...
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