kb3uet Posted February 9, 2019 Share Posted February 9, 2019 So last night the wife and I were out with some friends, and they told me i had no tail lights. I checked and I have brake lights and turn signals and backup lights, but no running lights or tag lights. Dash lights are still working and even dim with the switch. Fuses look good (all of them, I checked all of them). I did put a backup lamp in the left side yesterday and just for giggles pulled the ground off and cleaned it up a little more than I did before (can't think a clean ground would be the issue but hey you never know). I'm going to get new bulbs here shortly cause the ones in it were sketchy at best, but worked. Checked everything with amber bulbs last night and it didn't make a difference on what worked and what didn't. Any help would be appreciated, I am going to check the plug under the bed here shortly. Could the multi switch, brake light switch, or headlight switch be the culprit as well? Thanks. 1990 MJ Sport Truck. 4.0L 5spd 2wd Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted February 9, 2019 Share Posted February 9, 2019 Has anyone wired in a trailer harness ? If so check for broken/corroded wires there . Also check the plug for the rear harness for corrosion. Link to comment Share on other sites More sharing options...
Pete M Posted February 9, 2019 Share Posted February 9, 2019 do the front running lights work? Link to comment Share on other sites More sharing options...
kb3uet Posted February 9, 2019 Author Share Posted February 9, 2019 From what I can tell no one has ever messed with the wiring in the back. All the lights up front work. I was having an issue with the left turn signal, I had to tweak the contacts in the new socket and life is good with that. Link to comment Share on other sites More sharing options...
Pete M Posted February 9, 2019 Share Posted February 9, 2019 if it's not the bulbs themselves, my money is on the harness connector behind the drivers side rear tire. Link to comment Share on other sites More sharing options...
kb3uet Posted February 9, 2019 Author Share Posted February 9, 2019 That seems like a hot spot. I will start there and keep everyone updated. Link to comment Share on other sites More sharing options...
Eagle Posted February 9, 2019 Share Posted February 9, 2019 If the front running lights, the brake lights, and the turn signals work, then the multi switch, brake light switch, or headlight switch can't be the problem. It has to be in the wiring to the back, or possibly the sockets (although both going bad at the same time seems unlikely). Link to comment Share on other sites More sharing options...
PIKE Posted February 9, 2019 Share Posted February 9, 2019 I had the same problem years ago. It was caused by clutch fluid dripping on the fuse panel. Link to comment Share on other sites More sharing options...
kb3uet Posted February 9, 2019 Author Share Posted February 9, 2019 Thanks for all the input, and hopefully this will be of good use later on down the road. The problem was the blue tail light wire going to the plug in the rear. About 1/2 inch before the plug there was a bad spot and when I unplugged the connector the wire broke. Soldered it back together and so far so good. Link to comment Share on other sites More sharing options...
Pete M Posted February 9, 2019 Share Posted February 9, 2019 excellent! The old wiring is notorious for issues. Vigilance is key! After I loss my brake lights due to corrosion in that connector, I made it a point to check them every day (it was my daily driver at the time). Link to comment Share on other sites More sharing options...
Eagle Posted February 10, 2019 Share Posted February 10, 2019 The old broken wire trick will do it every time. Never overlook the simple when diagnosing. Many years ago, my pony car developed a funny skip/stumble. I had just done a tune-up, and the miles were getting up there, so I assumed (bad idea) that it must be something serious. So, I bought a junkyard engine, did a full rebuild, put it into the car -- and I had the same skip/stumble. Okay, it must be carburetor. So I bought a new carburetor and installed that. Still had the same skip/stumble. The problem was the $2 condenser from the tune-up kit I had just installed. Replaced the condenser and all was well. So, basically, I spent over $1,000 because I didn't take the time to diagnose a $2 part. Link to comment Share on other sites More sharing options...
rokinn Posted February 10, 2019 Share Posted February 10, 2019 I rebuilt a VW bus engine only to find out afterward that the fault was really the inaccurate compression tester that I borrowed from my buddy that owned an auto repair shop. One should always follow the old carpenter's adage, measure twice cut once. And then there's, I cut it twice and it's still too short! Link to comment Share on other sites More sharing options...
RowerJim Posted February 12, 2019 Share Posted February 12, 2019 On 2/9/2019 at 5:30 AM, kb3uet said: So last night the wife and I were out with some friends, and they told me i had no tail lights. I checked and I have brake lights and turn signals and backup lights, but no running lights or tag lights. Dash lights are still working and even dim with the switch. Fuses look good (all of them, I checked all of them). I did put a backup lamp in the left side yesterday and just for giggles pulled the ground off and cleaned it up a little more than I did before (can't think a clean ground would be the issue but hey you never know). I'm going to get new bulbs here shortly cause the ones in it were sketchy at best, but worked. Checked everything with amber bulbs last night and it didn't make a difference on what worked and what didn't. Any help would be appreciated, I am going to check the plug under the bed here shortly. Could the multi switch, brake light switch, or headlight switch be the culprit as well? Thanks. 1990 MJ Sport Truck. 4.0L 5spd 2wd Alright, I have had nearly the same issue going since I inherited my MJ from my wife's Gpa. Brake lights and head lights are all good, but parking lights/running lights in the back are out and my dash lights are out. This weekend I'm planning to pull the dash and switch bulbs. As for the running lights in the back, I was wondering how to change those out. I pulled the light cap off after removing the four screws and it looks like I need to splice wiring to put in new lights. Is that the case? If so, is it worth converting to LED or something? Looking to get the parts in and get to work sooner than later. Right now it is only a day time driver, which has been kind of a bummer. Thanks guys, appreciate all the help Link to comment Share on other sites More sharing options...
Pete M Posted February 12, 2019 Share Posted February 12, 2019 do you have power to the lights out back? are the bulbs the proper double filament? Link to comment Share on other sites More sharing options...
gogmorgo Posted February 12, 2019 Share Posted February 12, 2019 To change the taillight bulbs, you need to remove the screws holding in the taillight lens assembly (two in the light and two more you need to drop the tailgate to get to). Then the socket should twist out of the lens assembly, probably while pressing a tab on them... it's been a while. Then the bulb itself will twist out of the socket, press it in gently and turn. As Pete said, make sure the bulbs are correct for what should be in the sockets. But personally, for a problem with parking, tail, and dash lights, there's one major connecting point between them, it's a known point of failure, and coincidences usually aren't. I'd take a good look at the headlight switch while you've got the dash apart to change the cluster bulbs. Link to comment Share on other sites More sharing options...
kryptronic Posted February 12, 2019 Share Posted February 12, 2019 If you get as far as the headlight switch, you should also be checking for loose wiring at the base of the steering column - sometimes wires loosen in the connectors there and the lights all run through there. Also a bad multiswitch (turn signal switch) can cause weird lighting issues. Link to comment Share on other sites More sharing options...
Minuit Posted February 12, 2019 Share Posted February 12, 2019 47 minutes ago, kryptronic said: If you get as far as the headlight switch, you should also be checking for loose wiring at the base of the steering column - sometimes wires loosen in the connectors there and the lights all run through there. Also a bad multiswitch (turn signal switch) can cause weird lighting issues. This. Not long after I swapped to a tilt steering column, I lost my brake lights. Turns out I must not have plugged in the turn signal switch connector all the way, because it was halfway unplugged. Link to comment Share on other sites More sharing options...
RowerJim Posted February 13, 2019 Share Posted February 13, 2019 On 2/11/2019 at 8:43 PM, Pete M said: do you have power to the lights out back? are the bulbs the proper double filament? Yes, I have power to the brake lights in the back. The bulbs appear look like double filament to me, though one of them is a bit loose so that could be part of the issue. Link to comment Share on other sites More sharing options...
RowerJim Posted February 13, 2019 Share Posted February 13, 2019 On 2/11/2019 at 9:39 PM, gogmorgo said: To change the taillight bulbs, you need to remove the screws holding in the taillight lens assembly (two in the light and two more you need to drop the tailgate to get to). Then the socket should twist out of the lens assembly, probably while pressing a tab on them... it's been a while. Then the bulb itself will twist out of the socket, press it in gently and turn. As Pete said, make sure the bulbs are correct for what should be in the sockets. But personally, for a problem with parking, tail, and dash lights, there's one major connecting point between them, it's a known point of failure, and coincidences usually aren't. I'd take a good look at the headlight switch while you've got the dash apart to change the cluster bulbs. Hey, I took the lens off and was able to remove them from the lens assembly but trying to take the bulbs out of the socket does not seem to be working. Maybe I'm being a bit to gentle with them but I'm giving them a good twist and they are budging. Then I found some "replacements" online showing new wires coming out, which made me think I need to just cut the wire and splice in the "replacements". If I'm not trying to upgrade, I'd prefer to just do a quick bulb change before I start cutting wires. Didnt want to jump ahead and cut all the wires out, but if I went that route at least I'd know the problem. haha Link to comment Share on other sites More sharing options...
kryptronic Posted February 13, 2019 Share Posted February 13, 2019 1 minute ago, RowerJim said: Hey, I took the lens off and was able to remove them from the lens assembly but trying to take the bulbs out of the socket does not seem to be working. Maybe I'm being a bit to gentle with them but I'm giving them a good twist and they are budging. Then I found some "replacements" online showing new wires coming out, which made me think I need to just cut the wire and splice in the "replacements". If I'm not trying to upgrade, I'd prefer to just do a quick bulb change before I start cutting wires. Didnt want to jump ahead and cut all the wires out, but if I went that route at least I'd know the problem. haha Don"t cut. Push in and twist to remove the bulbs. You may be working against a little corrosion. Link to comment Share on other sites More sharing options...
gogmorgo Posted February 14, 2019 Share Posted February 14, 2019 Yeah, push in like 1/16" or so and twist counter clockwise. Some dielectric greases seem to harden up over time, which can make it sticky. Link to comment Share on other sites More sharing options...
RowerJim Posted March 3, 2019 Share Posted March 3, 2019 Figured I'd give an update for anyone interested. Changed the bulbs and still no dice. Then today I was working on the sound deadening project and noticed the fuses and decided to check. Sure enough, blow fuse. Lesson learned, start with the simple solution. Link to comment Share on other sites More sharing options...
Eagle Posted March 3, 2019 Share Posted March 3, 2019 4 hours ago, RowerJim said: Lesson learned, start with the simple solution. See my post above, from February 10. Link to comment Share on other sites More sharing options...
RowerJim Posted March 3, 2019 Share Posted March 3, 2019 11 hours ago, Eagle said: See my post above, from February 10. Lol, sometimes you just have to make the mistakes yourself to learn. Luckily for me I didn’t go as deep as you did. Link to comment Share on other sites More sharing options...
Pete M Posted March 3, 2019 Share Posted March 3, 2019 I keep telling myself that the best way to learn is from other people's mistakes, but my brain doesn't seem to listen. Link to comment Share on other sites More sharing options...
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