Trans Am Information > Electrical

Turn signals inoperative


Iíve reached the point where Iíve exhausted my troubleshooting skills and need more opinions, so please help if you can.

1979 Firebird Trans Am that Iíve restored from scratch (so everything is my fault).  Iím in the 40-60 miles on the odometer phase and have worked out many bugs, but this electrical gremlin is kicking my butt.

Turn signals are inoperative and here is what Iíve put together so far:
- Hazard flashers, Headlights, taillights, dash gauges, and parking lights appear to function normally (all bulbs are correct)
- 11.6V to turn signal flasher (pink striped black wire) when key in ďonĒ position, 0V when key off (believe thatís normal).
- Bench tested flasher and it functions (itís also new)
- removed and jumped flasher to remove that variable and voltage is still there until turn signal is up or down where voltage goes to near 0 at that junction (this has me confusedÖwhereís it going?).
- continuity checks are confusing:  From flasher output (purple wire) to front driver bulb (either contact) is open with signal lever off and 0 ohms with lever down.  Grounding tab at that bulb is a good ground. Both contacts are grounded with lever down (this is confusing to me, is that normal?).
- with brakes pressed and brake lights on, lever down turns off left rear brake light and lever up turns off right rear brake light (believe interrupting the brake light is normal, except the light is then supposed to flash).
- the battery is grounded to the engine block and core support.  Engine block is grounded to the sub frame and the firewall.
- the front light harness is grounded to the core support on both sides.  The rear light harness is grounded in the trunk and under near the fuel fill neck.

I think Iíve ruled out a bad flasher, some grounds, and bad or wrong bulbs.  Anything else?
Does that leave a bad ground somewhere other than what I said above and the turn signal switch?

Thanks in advance for any help.

Your 4th bullet point confuses me a little. Can you explain what you mean?

As for the following bullet point, you say ďboth cintactsare grounded with the lever downĒ. I donít believe that should be the case. Iím no electrical engineer but Iíve donít a fair amount of troubleshooting on my car. If youíre testing the contacts in the socket Iíd consider unplugging the socket and test the terminals at the plug. Sockets can go bad. I had some strange grounding issues with my front sockets.

Your description of the brake lights going out is normal as you suspected. If all else fails, itís possible your switch in the column is faulty. I donít think theyíre expensive. Just a small pain to change but not terrible.

Sure,I didnít make it very clear.  I made a jumper wire to plug in where the turn signal flasher goes to hardwire the connection between the flasher input (pink/black wire) and the flasher output (purple wire).  With the key on and lever off, there is 12V at that jumper wire location.  If I select up or down on the lever, the voltage goes to near zero at that same location.

Well, now they are working.  I wish I knew what was wrong, but Iím not sure.  I spent the weekend troubleshooting, cleaning contacts, inspecting wires, and puzzling over the multi meter readings.  None of which helped.  Then I decided to check voltage again at the fuse box and when I pushed the probe onto the fuse holder I heard the flasher start clicking.  Now everything works fine.  So, maybe itís a questionable contact between the fuse and the holder or some precarious short behind the fuse block that moved just right when I pushed on it with the probe?  This gremlin will most likely be back.
Thanks for the help b_hill.

Gotcha, thanks for the clarification. Thatís what I thought you meant but wanted to be sure. I donít quite get that. Again, not an electrical engineer but I donít suspect thatís supposed to happen. I know you said the flasher was new and tested but just for fun have you tried installing the hazard flasher in there just to see? I imagine thereís a short somewhere causing voltage to be lost on that circuit but Iím not sure how or why to be honest. Iíll see what I can come up with.

EDIT: no problem lol. Sorry I wasnít more help but Iím glad you got them working.


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