Just repalced the rear wiring harness on my 67 Malibu because the tail lights didn't work, and they still don't. Brake and signal lights work fine. Any advise? Thanks, Sam

Does the tag lamp work? It's fed from the same source as taillights. Check fuses under the instrument panel. Check for proper ground wire at rear of car. The harness for taillights is a ribbon cable running under the driver's seat in a floorboard depression. The harness may have a bad spot in it.

Where woud the ground be? There wasn't a ground to connect when I plugged in the harness. I am really new at this. Thanks

I have discovered that the stock bulb holder was just bad. Ane was able to buy a replacement bulb holder at my parts store. Spliced it in, and everything worked.

the bulb holder is the ground. I replace my bulb holders with all metal ones I bought at the local parts store. The plastic holders have one small metal part that is supposed to ground.

the bulb holder is the ground. I replace my bulb holders with all metal ones I bought at the local parts store. The plastic holders have one small metal part that is supposed to ground.


Thanks Herbie, That's the best info I have gotten so far, expalins how there are only 2 wires going into the bulb holder. I probably need to scrape away some paint around the hole for good contact. I'll check it out later. Thanks again!! Sam

,,,,because the tail lights didn't work, and they still don't. Brake and signal lights work fine. Any advise?

If your brake/signal lights work it, 99% it isn't a grounding issue. It's a 2 filament bulb that shares a common ground (through the socket/housing/car body).

You really should have a wiring diagram! Hopefully your new harness has some documentation or labeling as to what wire is what, and you can "reverse engineer".

Start at where the new harness plugs into the old. The taillight/license lights are all on the same circuit/wire.
- Find that wire at the connector, make note of the mating side wire color/strip segment and unplug the connector.
- Turn on the taillights.
- Using a test light (or better yet a meter) probe the contact point going forward/to the fuseblock.
- Is there 12V?
Yes = problem in the mating connector, new harness, or bulbs.
No = problem further up the circuit towards the fuseblock.

If "no", continue following that circuit forward until you find +12V. It's going to be a single wire all the way up through the headlight switch via the fuseblock.

I'm gonna guess your problem was never the rear harness, it's somewhere up front. Bad fuse "grippers", headlight switch or switch connections, or the connectors on the intermediate harness.

John, Thanks for the info. Not sure exactly what the issue was, but the lights are all working. I just messed with the metal grounds on the plugs, and made sure the bulbs were in the plugs correctly, replaced both bulbs even though they looked fine, and now they're both working. One thing this site is great for is helping to find a starting point when troublshooting. Thanks again. Sam