What To Test On A 2001 GMC Yukon With Power At The Trailer Taillight Ports On A 7-Way At All Times

Question:

Hello: 2001 Yukon, any ideas on why I would have 2vdc on the flat pin connector on both the LandR turn signal sockets? All the time. It is an adapter plugged into the 7 pin so Im sure it is also present before the adapter. No DRLs or lights on, just sitting at idle. Thanx

asked by: David A

Expert Reply:

From what you are describing, it sounds like you either have a short or bad ground somewhere. A quick way to see if it is just the adapter will be to pull it off and test the 7-Way on your 2001 GMC Yukon. If this tests good, you will just need to replace the adapter and be on your way. If this is the case, the Hopkins # 47345 is a nice 7-Way to 4-Way adapter as it has test lights on it. However, if your 7-Way is not testing properly, it does get a lot more difficult.

If you have a factory 7-Way, you will need to test the wires at the back of your 7-Way to see if the issue persists. If this is good, you will need to replace your 7-Way as this is where the short is. For this, I highly recommend the Hopkins # HM40975. This is what is being used on the new GM trucks and full size SUVs and it has a 7-Way and 4-Way, so you will not need an adapter anymore.

If your 7-Way is an aftermarket part, you will proceed in much the same manner. The first deviation will be checking the ground connection though. These go bad over time and can cause any number of odd things to happen. Once this is checked and or repaired/relocated, you will need to check and see if the 7-Way is piggybacking off a 4-Flat, like the # C59496. If you do have one of these, test the wires after and before the black box. If they are good going in but not coming out, replace it with the # C59496.

If the wires are still testing weird before the 7-Way or before a 4-Flat converter, you will need to take your Yukon to an auto shop to have the issue diagnosed and repaired, unfortunately.