Left and right parking lights stay on?

DDIXON32

MEMBER
2008 CHEVROLET SILVERADO
4.8L
V8
4WD
AUTOMATIC
280,000 MILES

Greetings,

Upon shutting off my truck, I observed that the Right and Left parking lamps, both front and back, remain illuminated. To investigate this issue, I have conducted some basic troubleshooting steps:

1. The only fuse that had an impact on the lights was fuse 28, which controls the Right Driver's Side Parking Lamp. Unplugging this fuse removed power from the driver's side parking lights. Conversely, unplugging fuse 27 did not have any effect on the passenger side lights.

2. Additionally, I disconnected all components from the rear junction box, located underneath the tailgate, but the Left and Right parking lamps still remained in their powered-on state. This was done to eliminate it as a possible cause of the problem.

Although the fuse box does not appear to have been tampered with by any small rodents, it could still be the culprit. The more likely cause is that the wiring harness is faulty, possibly due to a short. At this point, I am hoping that the first part of my troubleshooting process will aid in identifying the underlying issue.

Has anybody experienced this before / or have any tips?
Thank you.

6 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,625 POSTS

This sounds like the parking lamp relay is stuck on. Here is the location so you can swap it out. If this does not fix the problem, I would try unplugging the headlight switch. Here are the wiring diagrams for the running lights and blinkers which you can see the BCM is involved with the controls which will be the last destination on the trail to fix it. Also, I have included the BCM replacement instructions as well in case you need them. You can get a preprogrammed unit by searching Google or Ebay. Check out the images (below). Let us know what happens and please upload pictures or videos of the problem.

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Tuesday, February 28th, 2023 AT 11:09 AM

DDIXON32

MEMBER
4 POSTS

You don't believe this is a shorted wire? Is there a particular reason why not? (I am trying to learn)

To clarify, you're suggesting:
1. Swap the relay (I will do it tonight).
2. Unplug the headlight switch (Also easy. When I unplug the switch. If this was the problem, will the lights turn off or is there another step I need to take?)
3. If it is neither 1 or 2 swap out the BMC.
Correct?

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Tuesday, February 28th, 2023 AT 11:20 AM

DDIXON32

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4 POSTS

Update!

1. I swapped the relay with another OEM relay. Started the truck. Shut off the truck. No fix

2. I unplugged the headlight switch. Started the truck. Shut off the truck. No fix

After this. It leaves me with only 3 possible options, right?
Short
Fuse Box
and
BCM

Because tracking a short is free. I started pulling fuses again.
Pulling fuses 27 OR 28 will power off the driver's side? Seems very odd. I cannot get the passenger side to power off.

I removed the grille to get a closer look at the harness. On the driver's side below the headlamp is where the harness meets (for the left and right headlights.) That location is covered with antifreeze at the moment. A metal line from the radiator right above the harness is rusted terribly. Could this cause the shortage?

Thanks

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Tuesday, February 28th, 2023 AT 4:07 PM

KEN L

MASTER CERTIFIED MECHANIC
47,625 POSTS

Not unless it has rubbed through some wiring if not I am leaning towards the BCM.

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Wednesday, March 1st, 2023 AT 6:29 PM

DDIXON32

MEMBER
4 POSTS

Hello Ken!

Update. I unplugged the BCM completely and removed it from the truck. Should this have lost the power to my Passenger's side Parking lights?

With fuses 27/28 unplugged.
The battery is hooked up.
Headlight switch unplugged
BCM unplugged.

The parking lights on the passenger side are still on.

Thanks