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All 4 bulbs are new, 2 1157a up front, 2 1157 in back. Ignition switch on and left side turn signals both work ( front and back), right side rear turn signal works but front does not. Key off and headlight switch pulled out to first notch and front running light works but rear doesn’t. Any guesses? 1979 vette
Last edited by marciatoby; Oct 29, 2025 at 08:18 PM.
Reason: Forgot last sentence
Some things that may be going on: Check contacts inside the sockets for corrosion. Clean the contacts and wipe them with NO-OX-ID (aka battery grease, aids in electrical conduction) Check grounds. Has the headlight switch been replaced or is it original? Bad headlight switches cause all kinds of funky maladies as far as blinkers/running lights in these old C3’s. Have read many posts on here about such, then that switch is replaced and the issues go away.
No LEDs. I will check and test each socket. Also one more symptom to consider, when the headlight switch is pulled out to first notch or all the way out , the green dash light pointing to the right indicating right turn signal stays on steady. Does this have some significance?
Last edited by marciatoby; Oct 30, 2025 at 07:46 AM.
Reason: Added question
OK guys here is what I found. The right front turn signal socket was not getting ground or power to at least one leg. Fortunately the other end of this socket is a coupling that can be disconnected and that’s what I did. Next check for power and ground at this coupling with pigtail removed and all worked fine. The three flat plates on the pigtail that engage at this coupling were slightly corroded but really more of a hard crust on them that cleaned off easily and also the opposing three connectors on the harness were cleaned. Everything started working and also the green right turn signal indicator on the dash went away. Of course I removed the driver side identical pigtail and performed the same cleaning. Thanks for everyone’s input because it gave me a good starting point.
OK guys here is what I found. The right front turn signal socket was not getting ground or power to at least one leg. Fortunately the other end of this socket is a coupling that can be disconnected and that’s what I did. Next check for power and ground at this coupling with pigtail removed and all worked fine. The three flat plates on the pigtail that engage at this coupling were slightly corroded but really more of a hard crust on them that cleaned off easily and also the opposing three connectors on the harness were cleaned. Everything started working and also the green right turn signal indicator on the dash went away. Of course I removed the driver side identical pigtail and performed the same cleaning. Thanks for everyone’s input because it gave me a good starting point.
I found the same gunk in the front side marker sockets in my 80. I hope you don't mind if I add your comment to my LED thread. Perhaps that gunk is factory, but only lasts 40ish years.