Axeminister Posted February 12, 2017 Share Posted February 12, 2017 Hey guys i have an 87 MJ and the tail lights and one brake light are out. I have read the write ups elsewhere on the forums regarding this problem but i would like to lay out everything ive done and see where i can go from here. I'm a full time state employee and a full time student at the University of Tennessee. I'm getting pulled over regularly and its a drain on everything i do, so help would be appreciated and if your in the knoxville area i would readily pay for assistance. Tail lights out: The tail lights stopped working which led me to replace the headlight switch, fix 3 bad connections, and rewire the ground in the driver side taillight. All of this resulted in the taillights working for about 2 miles then caput. I retraced those steps and no luck. I have tested the wires in the headlight switch harness and all show power. I have tested the fuse connector and they show power. The power coming from the fuse is dead for all rear lights except one brake light and the hazards which are on another fuse. I have checked the fuse box for moisture from a leaking master cylinder and all checks out. Interior dash lights work, headlights and blinkers work. All other electricals work. I have been detailed as i can be and have done a bunch of due diligence on this forum and my own time investigating but I'm at my very wits end and i have no idea where to go from here. PLEASE HELP Link to comment Share on other sites More sharing options...
87MJTIM Posted February 12, 2017 Share Posted February 12, 2017 Do you have trailer lights wired in? If it was not done properly, it may be causing the issues. Have you check the light bulbs? The brake/turn lights are dual filaments. If you have an incorrect bulb in the socket it will cause lighting issues. Link to comment Share on other sites More sharing options...
Axeminister Posted February 12, 2017 Author Share Posted February 12, 2017 Ill check the trailer lights. I replaced the bulbs myself with dual filament, so those should be good Link to comment Share on other sites More sharing options...
Old man with MJ Posted February 13, 2017 Share Posted February 13, 2017 Check the switch on the brake pedal for power on both sides, make sure the connectors are tight. I replaced mine, and tried to solder only those wires wouldn't hold solder,used a push on connectors instead. Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 13, 2017 Share Posted February 13, 2017 Disconnect the rear lighting connector behind the bumper, then using a test light check & verify all the outputs are there on the correct connector pins. If they are, the problem is caused downstream from the connector, like trailer wiring, bulbs/sockets, etc. Link to comment Share on other sites More sharing options...
Pete M Posted February 13, 2017 Share Posted February 13, 2017 the harness connector right behind the drivers side rear tire is a known headache point. :( Link to comment Share on other sites More sharing options...
Axeminister Posted February 13, 2017 Author Share Posted February 13, 2017 Ill check the rear connector. I used the voltage checker light and there is no power at the connector in the cab near the fuse box or in the lines at the rear...fuse box shows there is power going to the lines and at least two show power but the rest are dark from the fuse box to the light. Could a break or faulty connector at the rear cause power in the front coming from the fuse box to also break? Link to comment Share on other sites More sharing options...
mikekaz1 Posted February 14, 2017 Share Posted February 14, 2017 personally.... stay away from light probes. use a real multimeter. Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 14, 2017 Share Posted February 14, 2017 Always use a grounded test light when troubleshooting lighting feed circuits especially if there may be LED bulbs present. Using an incandescent test light helps eliminate false readings caused by ground loops. Link to comment Share on other sites More sharing options...
Axeminister Posted February 15, 2017 Author Share Posted February 15, 2017 Ill invest in the multimeter this weekend. Here is the latest. The wiring for the rear end comes up under the driver side seat and around to a connector above/near the emergency brake. I disconnected the connector and tested each one for power, in hopes to find the break was happening after that connector or before. On the fuse box side i am only getting two wires showing light, the blue and tan, which are directly beside each other. I'm guessing this is the brakes and hazards? My fuse box shows power to the socket and my fuse is fresh, but power isnt making it to the first connector. Does this help explain anything further? Link to comment Share on other sites More sharing options...
ParadiseMJ Posted February 18, 2017 Share Posted February 18, 2017 Have you replaced any sockets, this particular socket? I had to replace 2 sockets on my 88. Don't know where you're from but I live out west and I have very little, if any rust or corrosion on my rig....but the sockets were toast...that and cutting splices and soldering my trailer wiring fixed all my lighting my issues Link to comment Share on other sites More sharing options...
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