moparvwfreak Posted January 6, 2009 Report Share Posted January 6, 2009 alright. i am working on a 72 620, yes a true 72. built 5/72. and the headlight LOW beams dont work. found out the guy burnt out BOTH lows at the same time. weird i knwo but it happened. so we put new bulbs in and they worked, for about 30 min then quit. power to the relay, power out from the relay on both low and high. yet the lows dont work at all. i have gone through and tested every switch, the relay, and all the wiring to find it all works. also the fuse box HAS been replaced with one from a later 620. and yes its good.all new fuses, and of course new 5006 headlamps. any ideas before i go through and rewire the headlight system??? Quote Link to comment
datzenmike Posted January 6, 2009 Report Share Posted January 6, 2009 The fact that it worked is a good sign that it wired properly. Ok Find the headlight relay. It will have a Red wire supplying power from the headlight switch in the ON position. If low beams are selected, power comes out of the relay on the Red/Black stripe wire and goes to both low beam filaments. At the headlight, the Black wire goes to a nearby ground, usually a screw in the rad support... just follow the Black wire. If it's corroded or not making contact the high beams likely don't work too. Check the negative post on the battery. Somewhere there should be a black wire going to the body sheet metal, again usually between the battery and the voltage regulator on the inner fender area. Unscrew, clean and tighten it up and you're good to go.The headlight ground might even be attached to this point. If you have trouble, make a ground connection and splice into the Black wire that comes from the headlights. As long as it is well grounded the lights should work. Quote Link to comment
moparvwfreak Posted January 6, 2009 Author Report Share Posted January 6, 2009 been done and done. i spent several hours tracing every wire, cleaning and relubing the switches, and they worked for about 20 min then the lows only died again. i also made sure the power to teh relay, red wire, was at 12v. like i said this makes no sense unless BOTH lows burnt out again at the same time. and the bulbs are Sylvainia halogens. as were the ones we pulled out. Quote Link to comment
kelowg Posted March 13, 2009 Report Share Posted March 13, 2009 make sure the truck isn't overcharging. i had the same thing happen to me Quote Link to comment
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