EDIT: Post 12 has the solution. I recently acquired this modestly rusted 1971 GS Convertible. I have gone through all of the lights to make sure the chassis wiring to them that is accessible and the sockets are clean and functional. It been some time since I've had to run down a turn signal issue especially on an A-Body, but I am thinking it is a ground problem - not sure where. The issue: When signalling a left turn the left front marker on the fender and the lower bumper light flash in sync IF the headlights are off. IF the headlights are on, the lights never illuminate (always off no flashing) VERSUS (and I think the Right side is working correctly) Signalling right the right front marker and fender will flash alternate of each other. with head lights on, flashing works fine, lights illuminate and pulse during a signal right. Flashers appear to work on 3 of 4 corners except for front left corner marker light and lower bumper light. Any advice to expedite troubleshooting appreciated. Thanks in advance -Chad
Sounds like you may have a bad bulb try new bulbs see what happens also double check the ground wire on the radiator support.
All bulbs check out good both filaments, but didn't know about rad support gnd. I guess I'll track that down. Fingers crossed.
Ok, Found the core support ground. It seems to be good going to the harness. For added assurance, I have a direct wire from battery negative to core support. Now the problem is: When headlights are on the left turn indicator in the dash illuminates solid. The turn signal works find now and the dash left indicator will flash as well. Seems like still another ground issue, meaning more than one ground is bad for the left side lights. I should have added that the GEN light stays on when car running and the battery does not charge so maybe there are two or more issues the first being solved with the core support being grounded. The GEN light issue has existed since receiving the car. Whats more, the fuel level indicator isn't functional - stuck on full. So between the alternator/regular and the additional symptoms do I have a dash ground issue or maybe an engine wire harness issue? Branded engine to body cable appears good. Where to look next? Maybe direct ground the body to the battery? I guess its time to pull out the book and look up troubleshooting steps.
Removed old alternator and installed an internal regulated one. Gen Light goes off and battery charging. Now back to focusing on the left turn signal problem.
A bad bulb will do that. There are two filaments in the bulb. Sometimes one filament breaks off & crosses/lands on the other filament causing EXACTLY what your talking about. On the fuel gauge follows Jason's thread about the fuel gauge system. Do a search. It's very easy once you know how. Tom T.
Ok, After reluctantly but methodically going through all the wire connections...a few brain cells fired off and I recalled having the EXACT same issue on my 70 Riviera. The problem: When headlights are on a turn signal indicator illuminates in the dash and the lights in the fender and bumper on the given side do not illuminate. The root cause of this is a ground issue in the bumper Corner/Turn signal socket. Upon close examination, the black ground wire is crimped to the locking plate, that locking plate rusts and eventually separates causing a floating ground. Solution: Replace the socket and/or find a means to restore that ground connection. Some may cringe, but I simply added a small screw in the gap because it does not interfere with the rubber seal, I am not splicing an otherwise perfect wire harness, and the new "GM" socket did not fit right. I did not want to keep buying a returning sockets. Pictures to help illustrate.
