Cruzn620 Posted October 14, 2007 Report Share Posted October 14, 2007 Alright, i am trying to get my '79 620KC road worthy so today i started checking lights. my head lights and front markers work fine, brights work fine, but i have no tails, rear markers or blinkers. assuming my fuses are good (it was too dark to tell...forgot the flash light) what other things do i need to check. possibly a fault with something like a brake light switch or what? i guess if worse comes to worse i will just trace the wiring down till i find where i am coming up short (no pun intended) but i was thinking their may be a common problem on these trucks that you guys might know about. thanks! Quote Link to comment
datzenmike Posted October 14, 2007 Report Share Posted October 14, 2007 Alright, i am trying to get my '79 620KC road worthy so today i started checking lights. my head lights and front markers work fine, brights work fine, but i have no tails, rear markers or blinkers. assuming my fuses are good (it was too dark to tell...forgot the flash light) what other things do i need to check. possibly a fault with something like a brake light switch or what? i guess if worse comes to worse i will just trace the wiring down till i find where i am coming up short (no pun intended) but i was thinking their may be a common problem on these trucks that you guys might know about. thanks! Tyler, start with the harness that comes from the cab and follows the pass side frame back to the pass tail light assy. At, or near, the rear pass tail light is a round white 6 pin connector. Unplug and check for corrosion or a bad connection by repeatedly plugging and unplugging and see if the lights flicker on. The most common fault is a bad ground return, (Black wire) without it, NONE of the lights will work. If this does not fix the problem go to the other end of the harness where it comes up through the floor into the cab. Just under the front of the pass seat (slide it back as far as it will go for access) there is a rectangular 10 pin connector, 6 for the tail lights and some others for the gas gauge and maybe electric fuel pump. Check for loose connection. These are the two easiest things to check and fix so should be done first. Next inspect the harness along it's length, from the cab to the rear, looking for any damage to the black tape wrapping. Maybe someone has wired in a trailer and the weather has got at the bare wire and corroded it. For the rest you will need a $5 to $10 12 volt test light. One end is an alligator clip and the other is a pointed probe that you can touch to wires or pins and a bulb will light if there is voltage or ground present. These are invaluable for working with wire harnesses. I'm going to assume this is a loose connector that you can easily find and leave this for now. Let me know how you make out and we can go from there. Quote Link to comment
BEEBANI Posted October 14, 2007 Report Share Posted October 14, 2007 Maybe a dumb question, but did you check all the bulbs? The 620 taillight assembly is notorious for filling up with shit and not letting the bulbs make good contact. I just pulled all my bulbs the other day and wire brushed the socket and the bulb. I had 2 bulbs that weren't working until I pulled and reinstalled them. Quote Link to comment
Cruzn620 Posted October 14, 2007 Author Report Share Posted October 14, 2007 hey mike, thanks so much for the heads up on the pin connector under the passengers seat. when i got the truck the fuel gauge worked...then i took the interior out to do the floor pans...doesnt work...now i know why!! i'll hook that connector back up, give it a try, and i'll be sure to check for corrosion and loose stuff under the truck as well. thanks bee for telling me about the bulbs, whether the pin connector is the problem or not ill make sure i get in there and clean the connectors well...no need for one of those fix it tickets! Quote Link to comment
datzenmike Posted October 14, 2007 Report Share Posted October 14, 2007 Once I got my connector clean, I tightly wrapped 3-4 rounds of vinyl electrical tape around the crack where the two connectors meet. Keeps the crap from the tires out and is easy to remove. Dip the ends of the light bulbs in white 'lithium' grease before installing in their sockets, this also prevents corrosion and keeps the crap out without affecting the contacts. Quote Link to comment
Cruzn620 Posted October 15, 2007 Author Report Share Posted October 15, 2007 yeah, i have 6 1959 caddy bullet tail lights in my s-10 that i drive daily. it uses those standard 1157 bulbs, and i live by the motto "in dielectric grease we trust!" stuff is a life saver! thanks again for the heads up Quote Link to comment
Cruzn620 Posted October 21, 2007 Author Report Share Posted October 21, 2007 plugged in the 10 pin connector...everything is working now. thanks for telling me that one, i would have chased my tail forever!!!! lights sure aren't very bright...so its alternator swap time! THANKS Quote Link to comment
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