Blinker only works when headlights off

[bennylava]

Hi all. I'm having some trouble with my blinker, which is preventing me from getting the required state inspection sticker. For some reason, my driver's side blinker will only work if the headlights are off. If I turn them on, that side won't blink.

When the headlights are on, I'm also getting the "check your blinker" signal. Meaning that the green blinker indicator in the cab stays lit up at all times. instead of just flashing when the blinker is turned on.

The truck sat in my driveway for 4 months, and before that everything was fine. Anyone ever had this problem? It's an 87 silverado 5.7L 700R4 if that helps any. Thanks!

[Dead Parrot]

The usual suspect for weird light behavior is a bad ground somewhere. In your case the current from the headlight could be maxing out the poor ground connection and the blinker bulb current doesn't flow.

In addition to cleaning the grounds for the blinker and headlight, clean the ground for the core support to battery if your truck has one. Clean and/or replace the motor to cab ground.

Since it sat for 4 months, possible mice or other critters did some work on your wiring.

[Getter-Done]

Loose front or rear light bulb sockets could cause this.
Also, poor ground as already mentioned.

Make sure engine is grounded to the frame,
Frame is grounded to radiator core support,
and bed is grounded to frame.

[bennylava]

Well, rather than try and track down that ground (I cleaned 4 grounding spots in the attempt) I just made a new one. It fixed the problem immediately.

https://i.imgur.com/dtBpxnF.jpg

[Getter-Done]

Glad you got it fixed

[bennylava]

Originally Posted by Getter-Done

Glad you got it fixed

Yeah that's the cool thing about grounds! I spent over an hour hunting and cleaning, and then I was like "Why am I doing this"?