Rear Running Lights not working

AARONPHILLIPS81

MEMBER
2009 GMC SIERRA
5.3L
5 CYL
2WD
AUTOMATIC
89,000 MILES

Recently noticed that my rear running lights are not working when my lights are on.
Brake lights work and blinkers work, but no running lights or license plate marker lights.

I have checked connections in the four position block the taillights connect to and everything was tight.
I have also checked some fuses under the hood as well as in the panel inside the vehicle. Not real sure which one powers this as it is not indicated.

Any ideas?

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

This could be a couple other issues. First, we need to check for power at the relay for the park lamps and that will help us determine if there is a circuit issue or a power issue in the BCM.

So, we need to remove the relay and check for ground at pin 86. The way the BCM turns on the relay is it provides ground to the power supplied to it.

So, we need to check for ground at pin 86 of the relay and go from there.

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Please check the wiring diagram and let me know what you find. Thanks

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