tail light out, brake light is still good

[High Five H2]

So this is probably a newbie question, but I figure I'll ask it before I tear into the truck just to save some time. My right rear turn signal quit working followed by the left rear turn signal a few days later. The brake lights still work, so it's not a bulb. Probably a relay, right? Where is the relay located? thanks in advance.

 

[Best4x4]

Pretty sure 3157's are dual element bulbs. Wouldn't hurt to remove the bulbs and inspect them. I've had bulbs go out right after each other before... If both elements on both bulbs look good then it's time to get out a meter and check voltages.

 

[High Five H2]

awesome, i'll check it out. fortunately, my brother is a CDL driver and he swiped some bulbs for me. I was going to go to LEDs but, hey, free bulbs.

 

[abearden]

Agreed, swap the cheap part first. If new bulbs doesn't fix it, then start looking for connection problems. Unlikely it's a relay for a one-then-the-other problem, but it happens.

 

[chad]

i have a similar problem and was told by gm it could be a bad bulb socket, you have to order the whole wiring harness which has a quick disconnect behind those rear storage panel area, i was quoted $34 for harness.

 

[alrock]

Could be a socket but it's typical to lose just one filament in these dual filament bulbs and that's of course a cheaper fix, and cheaper troubleshooting. jallen, glad you're starting with traditional bulbs for troubleshooting. If you end up going with LEDs at some point you'll probably need a resistor in line to reduce the rapid flashing of the turn signal.

 

[Diode Dynamics]

If you decide to swap to LED for your turn signals, you will 100% need to add resistors to prevent the hyperflash from occurring.

LEDs create very little resistance in comparison to the factory filament bulb, so your Hummer's "computer" will be tricked into thinking a bulb has gone bad. As the filament goes out on the incandescent bulb, it creates less resistance...that's how the hyperflashing starts and that's how the car's flasher tells you it's time to replace the bulb.

Nick C.

 

[chad]

Could be a socket but it's typical to lose just one filament in these dual filament bulbs and that's of course a cheaper fix, and cheaper troubleshooting. jallen, glad you're starting with traditional bulbs for troubleshooting. If you end up going with LEDs at some point you'll probably need a resistor in line to reduce the rapid flashing of the turn signal.

i took different bulbs and tried them in mine and checked the wiring, only thing i can think of is gotta be socket. although i only have one side out.

 

[High Five H2]

which resistors do I need? they're not part of the LED?

 

[Diode Dynamics]

which resistors do I need? they're not part of the LED?

If you are replacing the bulbs with LEDs you'll need to splice in some 6omh 50 watt resistors

Nick C.

 

[chad]

so i just checked mine, it was a fuse, kinda weird how the fuse only affected that one tail light and license plate light.