2004 Canyon Signal light issue

[e.p.]

Hi all;

I'm having issues with my 2004 GMC Canyon signal lights. When I press the brake pedal the left turn signal indicator on the dash lights up. When I select left turn signal all the indicator lights on the truck flash like they would if I turned on the hazards. Right signal works ok. All bulbs are good. I'm thinking body control module? Anybody else ever have this problem?

Any help is greatly appreciated.

Thanks.

 

[no HD]

 

I would check the ground for the left rear light first. Remove the light assembly and follow the black wire coming from the light socket and make sure of the connection.

Also you can do a test for the ground by using a 12V test light. Connect the alligator clip to a good ground on the truck and with the signal light on, touch the tip of the test light to the brass portion of the bulb base that's sticking up out of the socket. If the test light blinks then the bulb is trying to ground through the test light because the existing ground is not functional. If the test light stays off then your ground is good.

I have also seen the socket itself cause this or even a defective bulb. I'm sure after you tinker with it some you will have it figured out.

One troubleshooting tip I use is that I pretend the bcm or ecm or any other modules are not there and just check for power and grounds and 99% of the time you are successful.