:new: Hey everyone, was looking for help on a problem with my '89 C2500 and found you gents (and ladies) - thank goodness. Any/all help is much appreciated.

Might be an easy one for you: driver side taillights not working; brake light/turn signal & backup light on that side all work okay. Passenger side all okay. Not the bulb & the fuse is common for taillights. Help, please.

Should I "borrow" my friends multi-meter and what should I be checking for? Should mention that this has a trailering harness spliced in below and I checked for obvious wire insulation wear/tear and looseness but none found. The harness connecting to the light socket 'plate' is tight. I noticed some slight corrosion of the "plated wire or connector" that runs up from the middle bulb/socket to the top socket(?).

Thanks again all! The bulbs are C2507, I believe (they're flat vs. the 'old' round style).

Welcome to thebboard...there are quite a few people in here that have been great at diagnosing problems....how long has this problem been with you and what happened when it started? How do you know it is not the bulb? the brake and turn use both elements, the tail-light alone uses one. I'd get a circuit tester and start working through the circuit. I am unsure at this point what might be the problem besides the one element not lighting up. Stick around though...someone might have the exact answer you need.

The circuit boards for the taillights on these models are notorious fro causing intermittnt problems. Definitely try and meter it out. Another thing to check is to clean out the socket for the bulb. GM put some kinda goop in there that tends to solidify over time. That may be preventing good contact. If you need a new circuit board for the tailights, buy from the dealer. The ones from Advanced Auto/Autozone etc...are worth $.02 They will act up again and you are going nuts all over. The circuit board runs about $70, but your better off paying for it instead of chasing the problems a bad board can have.

Thanks to both, CANTBURN & Palf70Step!! Just fyi - the bulbs were checked in the passenger side sockets and I changed them out to new ones anyway, after verifying the new ones worked as well, in the right side taillight sockets. My suspicion is that the ckt board (aka socket assembly?, etc), Palf70Step, is involved; as you said. It looks a bit worn after 17 years (apprx 75K miles - just a baby, really, ...hah).

Would anyone know the wiring for that section? I saw, if memory serves: black, green, yellow, and some kind of off-red(?) maybe. How could I eliminate the wiring as a cause and narrow it down to the socket board?

Thanks for the advice on avoiding non-OEM stuff; I wll heed that. Is a salvage yard not a good idea for this part? Am I only asking for trouble not going dealer-new?

thx again...

Salvage yard might do, but you never know. that board is probably as old as yours and just as bad. The color coding varies from rightside to left side on one wire and I can't remember which one it is. Unless you feel/see a break or know some one has modified the harness your wires are probably OK.

advance auto parts carries these for about 30 bucks a pair

Does your turn signal indicator illuminate in a dim light, when you turn your headlights on. There is a possibility that your ground circuit on the rear tailight is bad and it is feeding back through the wiring (which will not give it enough for the tailights).

All, thanks for the feedback. I haven't had a chance to install it yet (too dang cold & windy out there for messing with nearly 20yr old plastic) but I stopped by the local Chev dealer and bought the taillight ckt board from them. Figured new would avoid picking up (sorry, bad pun) somebody else's problem or developing a new prob with the unit down the road. Dlr had one in stock so I decided to get it rather than wait and have to order it later.

Palf70step was right on the target on price ($63 & change+tax). Hurts but keeps the local LEO's from ticketing me on defective equipment.

Thanks for the help, everyone.

P.S. Was not experiencing the issue that piecesparts mentioned but appreciate the reply nonetheless. :cool: