Wife has a 01 2500 Ram that we just put new tail light assemblies and new 3d light in. It's her truck and her money, so I can't complain. Noticed a couple of days ago that the driver side backup light and the backup light in third light were not working. So spend about 2 hrs looking at the svc manual to no avail to find something common with both units. Looked thru the forum and wasn't able to find anything either. So HELP. I am figuring it has to be a common connection, but don't know where. She drives it all of the time and only time I get to check it is on my day off if she gets home early. She says my Blazer is too small, and I agree with her. Anyone had a similar problem? And what was the cause. I am going back to the manual an I might get lucky.

 

Check for voltage at the socket. Didn't know a backup light was in the third brake light. I thought those were cargo lights there.

 

Those are lights for the bed, not reverse lights.

 

Rained today so couldn't get out the meter to check voltages. I agree about the third light for cargo bed, but she found one the replaced the original and the LED's go on when it is in reverse. Can't figure out why as that would ruin your vision at night. OK just went out into the cold and checked the cargo lights. They are ok. Don't know how they lit up when it was put in reverse, but just made my job 75% easier. Thanx for whacking me alongside the head on that. Back to the schematic in the manual.

 

For them to go on in reverse you'd have to run wires or install a jumper somewhere upstream (at the switch possibly).

 

Or, if it was not a plug and play 3rd brake light and required cutting and splicing into the factory harness, perhaps the wiring was fubar'd.