[Efi69Cam]

2016 2SS...All others work, running lights on tail lamps light up both sides. Replaced bulb, reseated connectors behind bumper, marker assembly works when connected to front.



Any thoughts?

[Mark114]

It sounds like a wire harness problem. Is this the OEM side marker bulb with OEM wheels and tires?

[Efi69Cam]

Car is unmodified. I checked the harness behind the wheel well liner, no visible damage.

[arpad_m]

Originally Posted by Efi69Cam

Car is unmodified. I checked the harness behind the wheel well liner, no visible damage.

The wiring that goes to this bulb is part of the rear object sensor wire harness, see below. Check if rear cross traffic alert functionality works on the driver side (objects entering the sensor's range from the left), if not, it could be a fuse, otherwise I'd go through the rest of the harness with a voltmeter.

[Efi69Cam]

No messages regarding the cross traffic, parking, or blind spot detection on the cluster, I know the blind spot detection worked last time I drove it.
Would you know if both rear markers are on the same circuit? On old cars they were tied into the rear parking lamp circuit, but with everything going through the BCM, i can only guess.
I did check the continuity from the lamp connector to the main connector, but your picture tells me I can trace it all the way to the trunk behind the trunk trim, as the body harness goes from that side through the body behind the wheel well before connects to the bumper harness.

[arpad_m]

Okay, I see. Below is the schematic for these lights, the driver side front and rear markers are on the same fuse (F18, BCM fuse #4), so I doubt that would be the issue if you can move the marker assy to the front and it works there.

If everything else on this harness is functional, (did you check that whenever you're in R and a car passes behind you from the left, the beep and the red warning symbol comes on?) then it has to be a wire or a faulty ground connection, hopefully you can trace it. Sorry, this is all the help I can give, I've never encountered this issue before.

[Efi69Cam]

Thanks for the diagram. It verifies the common connection of the lh running light and markers. Circuit 709 is functional except for the rear marker lamp branch so I can eliminate fuses and the bcm. Maybe a defect in J361? I’m thinking j is junction and is where the harness branches out.

[Efi69Cam]

Used a tone probe to find the break in the connector coming off the body harness, wire broke at the terminal.

Connectors are molex mx150. Terminal and connectors are available from Mouser.

GM wants $100 for the pigtail, terminals are .40 each from mouser.

[arpad_m]

Originally Posted by Efi69Cam

Used a tone probe to find the break in the connector coming off the body harness, wire broke at the terminal.

Connectors are molex mx150. Terminal and connectors are available from Mouser.

GM wants $100 for the pigtail, terminals are .40 each from mouser.

Well, I'm not entirely sure I would choose the pigtail

Thanks for getting back to the thread with troubleshooting results.