Reverse lights Update

[513Tahoe]

Hey all, I finally got around to taking a look at my reverse light harness this past weekend. I tested both sides with a multimeter and the drivers side had 0 volts coming through. I checked the passenger side and only 9 volts came out. I decided to take a look at the fuse for the reverse lights and it didn't look blown when I took it out. I put it back in and the passenger side started showing 0 volts now. I used electronic contact cleaner for the reverse lights and still no power coming through. Have any of you guys dealt with something similar or have any clues on how to fix this? We have another 2014 tahoe ppv I want to try swapping the harness from that one to mine to see if that helps the issue.

 

[Joseph Garcia]

You 'could' have an issue in the wiring under that fuse. Unfortunately, rodents tend to like that space for wire munching and staying warm when appropriate.

 

[513Tahoe]

You 'could' have an issue in the wiring under that fuse. Unfortunately, rodents tend to like that space for wire munching and staying warm when appropriate.

I checked and there didn't seem to be any issues with damaged wiring underneath the fuse box. The car is from the Ohio Highway Patrol, and they do salt the roads heavily here. Perhaps there could be some corrosion underneath where they go into the ground. I recently replaced the housing for the tail lights because the previous ones would fill up with water when it rained. Should I go head and replaced them with new ones or try swapping them from my other tahoe?

 

[JoeBlobs]

I would check the upfitter's guide on this, but I'm fairly certain the reverse lights on your PPV would have also been tied into the headlight/taillight flasher module (mine are, anyway). I believe there is an RPO code for this which would be in said upfitter guide. It might be a good idea to locate your module and inspect and test it to see if its causing issues. You may also be able to bypass the module altogether. If I were you, I would locate the headlight/taillight flasher wire, power it up and see what happens. The harness would be under the dash, behind the center console.

Worse comes to worse, you could probably run a wire from your trailer harness to power your lights as well.

 

[513Tahoe]

I would check the upfitter's guide on this, but I'm fairly certain the reverse lights on your PPV would have also been tied into the headlight/taillight flasher module (mine are, anyway). I believe there is an RPO code for this which would be in said upfitter guide. It might be a good idea to locate your module and inspect and test it to see if its causing issues. You may also be able to bypass the module altogether. If I were you, I would locate the headlight/taillight flasher wire, power it up and see what happens. The harness would be under the dash, behind the center console.

Worse comes to worse, you could probably run a wire from your trailer harness to power your lights as well.

Where the center console would be, I found three wires labeled 6j4, 6j7 and wx7. There was a dark green wire spiced as well as a yellow wire. Would any of that affect it? They all are attached to connectors that would plug into something but i dont know what they would plug into. My silver 2014 ppv has the same thing but the reverse lamps work on it.

 

[JoeBlobs]

Where the center console would be, I found three wires labeled 6j4, 6j7 and wx7. There was a dark green wire spiced as well as a yellow wire. Would any of that affect it? They all are attached to connectors that would plug into something but i dont know what they would plug into. My silver 2014 ppv has the same thing but the reverse lamps work on it.

6J7 is your harness for the Headlight/Taillight flasher.

Here is the upfitter guide for our trucks. This is for 2014 but others can be found via Google. A lot of good info in there, definitely go through it.

I'll copy the info here in case the link ever goes down, there are wiring diagrams in there also, check them out.

Pg. 97

"The headlamp flashing module is activated by the application of 12 volts to a dark green/red wire in the upfitter harness. When the flashing module is turned on, the module sends a signal to the BCM which alternately flashes the stop lamps and backup lamps at the same flash rate as the headlamps. Depressing the brake pedal will override the stop lamp flashing and placing the transmission in Reverse will override the backup lamps flashing.

A 20-amp fuse labeled HEADLAMP WASH protects the flasher module circuit. The fuse is located in the under hood fuse block in the engine compartment on the driver side of the vehicle. See also the Owner Manual for more information.

Activation of the headlamps flashing and rear lamps flashing can be separated by opening the dark-blue/yellow BCM circuit at the flasher module connector, C122-F, and applying a customer-switched ground to the harness side of the wire at the connector. Power to dark green/red wire must be off to flash rear only.

Warning: BCM will be damaged if 12V power is connected to the dark-blue/yellow wire."

I'm not sure what is spliced into your wires, it sounds like they wanted to separate front and rear flashers as mentioned above. If it was me I would cut everything off of those wires, power up the activation wire, see if the reverse lights come on, then go from there. Check the fuse for the module. Visually inspect it for issues, corrosion, bad grounds, ect...

 

[513Tahoe]

6J7 is your harness for the Headlight/Taillight flasher.

Here is the upfitter guide for our trucks. This is for 2014 but others can be found via Google. A lot of good info in there, definitely go through it.

I'll copy the info here in case the link ever goes down, there are wiring diagrams in there also, check them out.

Pg. 97

"The headlamp flashing module is activated by the application of 12 volts to a dark green/red wire in the upfitter harness. When the flashing module is turned on, the module sends a signal to the BCM which alternately flashes the stop lamps and backup lamps at the same flash rate as the headlamps. Depressing the brake pedal will override the stop lamp flashing and placing the transmission in Reverse will override the backup lamps flashing.

A 20-amp fuse labeled HEADLAMP WASH protects the flasher module circuit. The fuse is located in the under hood fuse block in the engine compartment on the driver side of the vehicle. See also the Owner Manual for more information.

Activation of the headlamps flashing and rear lamps flashing can be separated by opening the dark-blue/yellow BCM circuit at the flasher module connector, C122-F, and applying a customer-switched ground to the harness side of the wire at the connector. Power to dark green/red wire must be off to flash rear only.

Warning: BCM will be damaged if 12V power is connected to the dark-blue/yellow wire."

I'm not sure what is spliced into your wires, it sounds like they wanted to separate front and rear flashers as mentioned above. If it was me I would cut everything off of those wires, power up the activation wire, see if the reverse lights come on, then go from there. Check the fuse for the module. Visually inspect it for issues, corrosion, bad grounds, ect...

I checked the fuse for the module, and it wasn't blown or corroded. I had swapped the harness from a 2014 Tahoe PPV to mine, and still the reverse lights wouldn't turn on. I looked at the grounds underneath the vehicle, and they looked in decent shape. I'm starting to believe that it is a BCM issue.

 

[JoeBlobs]

I checked the fuse for the module, and it wasn't blown or corroded. I had swapped the harness from a 2014 Tahoe PPV to mine, and still the reverse lights wouldn't turn on. I looked at the grounds underneath the vehicle, and they looked in decent shape. I'm starting to believe that it is a BCM issue.

If you find a BCM wiring diagram, locate the reverse wire and test for 12 volts when you put it in reverse. I would check trailer wiring as well.

 

[513Tahoe]

If you find a BCM wiring diagram, locate the reverse wire and test for 12 volts when you put it in reverse. I would check trailer wiring as well.

I wasn't able to find a BCM wiring diagram. I found the trailer wiring underneath, and nothing looks spliced or corroded. I tested the reverse light socket harness and grounded it with the rear studs, and still no power on the driver's side and only 9 on the passenger side. I'm currently a student and I don't have much knowledge of electronics knowledge but I know all of you guys are great resources.

 

[mikez71]