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73-87 Chevy _ GMC Trucks => Electrical => Topic started by: Sean in NE on February 08, 2015, 03:28:54 pm
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My truck is finally in the "getting the gremlins out" stage of the build. If it isn't one thing its another lol. Anyway, on the electrical side of things its strange. The vehicle is a 1989 "formally" R3500 with a "formally" 454 TBI and 4spd manual. The TBI was removed and is now just a carbureated engine with a MSD 6D ignition control module, running the HEI distributor. OK, now the problem I'm facing. First time I ran into this was after I installed my trailer brake controller. Hitting the manual brake button on it, I discovered all of my lights lit up and the headlight buzzer came on. Release the button, they went off. The lights im talking about were from and side park lights/turn signals, clearance lights on cab, lights in dually flares, and the tail lights were lit with the brake lights. Reverse lights work as they should. Headlights I did modify with a HD wiring harness that draws power direct from battery and not headlight switch, HID headlights(for lack of the proper term).
Also trying the turn signal results in: left blinker position, all lights blink(including right side). Right position, same as left. And Hazards everything blinks. The headlight buzzer goes with the blinking and sounds like a back-up alarm(annoying). The PO had what looked like an add on cruise control system. I removed that, and only the harness from the turn signal swith remains.
Also I have been up and down the chassis harness and had fixed what I thought could be the cause of this problem, but nothing works as it should yet. I have a wiring diagram, so no need of help in that department. Just need some fresh ideas from someone else that might have had an issue like this before. Thanks!
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ground issue or you wired the wires wrong
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A ground can do that? Never thought to try that. One thing I forgot about, I disconnected the plug at the end of the bed and tried the lights. With the rear unplugged the front blinkers worked like they should, gauge cluster stayed lit and wasn't bothered by the blinker/hazards. So its something in that bed. I'll keep everyone posted if I find something. Thanks!
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Insure the right bulbs are installed in the rear,also check the filaments in the bulb,one could have broken and laid across the taillight filament
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78BIG-TEN, you nailed down the problem. It indeed was the tail light bulbs. I had been trying to use led lights there, but couldn't get 2057's in led at the parts store. Thought 1157 LEDs would work, guess not. Running 2057 incandescents again and all works well. Thanks guys for your help!!!