2021 Gladiator - B16D7-11 Left Taillamp Control - Circuit Short To Battery Or Open.

Macdaddy4738

Macdaddy4738

Well-Known Member
Joined
Jun 1, 2005
Have a weird issue with my 21 Gladiator where the halo light on the outside of the left tail light no longer works. It's definitely NOT the light. If I swap it to the right side, the halo works. If I swap the right side light (which works fine) to the left, it doesn't work.

I decided to replace the wiring harness from the bumper back to the light to see if it was an issue there. Didn't fix it. Initially it threw out a ground fault issue. I dropped the spare tire and took the harness grounds off, cleaned them up and reattached them. No change.

I honestly have no idea what's going on. I'm electrically challenged so I have no clue how to trace this. My next idea is replace the harness from the sway bar link back to the bumper but that one is expensive and appears to be a pain to do.

Any suggestions or tips to figure this out? Driving me absolutely nuts!

Edit* I should add that it's not throwing a CEL. I'm pulling the code through JScan.
 
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If it uses a TIPM module like Chrysler or the like it could be in that unit. Modules control nearly all circuits these days. I would not rule out a control circuit over a hard wire or even terminal issue.
 
Ground is most likely the "trigger" wire also. This is also why it could be circuit board related as well. LED requires vary little fluctuation in a control circuit to create issues. We see it up fitting LEDs on brand new units.
 
WARRIORWELDING said:
If it uses a TIPM module like Chrysler or the like it could be in that unit. Modules control nearly all circuits these days. I would not rule out a control circuit over a hard wire or even terminal issue.
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Wouldn't I see more issues if it was a board issue? The lights work otherwise, just the single halo. I thought it could be something in the BCM itself but figured I'd see a lot more problems if that was the case.

I've also considered it being an aux battery issue. I know those are prone to go out about now given the age of the vehicle.
 
Macdaddy4738 said:
Wouldn't I see more issues if it was a board issue? The lights work otherwise, just the single halo. I thought it could be something in the BCM itself but figured I'd see a lot more problems if that was the case.

I've also considered it being an aux battery issue. I know those are prone to go out about now given the age of the vehicle.
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No I've seen individual tail lights give issues. However I don't know halo lights....does it also function as a signal light?
 
WARRIORWELDING said:
No I've seen individual tail lights give issues. However I don't know halo lights....does it also function as a signal light?
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Honestly I don't know! I'll have to look.
rony76 said:
If the rest of the lights are good, it’s probably something with the halo itself or its circuit, not the whole system. I’d say start by checking the grounds again, even though you cleaned them, those things can be sneaky.

Could also be a short in the wiring somewhere. That’s usually the culprit when one part of the light is acting up, but the rest is fine. Honestly, though, if you can’t track it down, maybe it’s worth taking it to a pro who can test the circuits.
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The left side (without the functional halo) works fine when plugged into the right side harness. The right side (with functional halo) doesn't work when plugged into the left side harness. That's why I sort of lean towards a wiring issue.
 
If the halo is not a signal light, then couldn’t it be powered by the same circuit as the right side halo? Like they should both always be on or off at the same time, right?
If so, could you cut and cap the wire from the vehicle harness to the left side, and then run a wire tapped off the right side halo over to the left halo?
I know that’s not resolving the root cause, but would get them both working?
 
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