Truck Issues – Fixed

This content has been archived. It may no longer be relevant

The other day I mentioned that my truck’s reverse lights were constantly on, and wouldn’t turn off. I checked all sorts of things and ruled out everything from the headache rack, to the in-bed 7-pin adapter, rear bumper, trailer cabling, and connectors. I found water in some of the connectors and thought that was the issue, but removed them and isolated the wires, and the issues continued. I pulled fuses from the fuse box that should have turned the lights off, but they remained on. Eventually, I decided the issue had to be with the fuse box, and that I wasn’t going to mess with that. Unfortunately, I can’t really believe that the dealer would take care of this under warranty, because there are a ton of things I’ve done to the truck that would likely be blamed. So I really wanted to solve this myself.

I suspected was the fuse box, but didn’t want to get that far into it. Ultimately, I decided to pull it today. This is the box sitting on my desk:

I disassembled the box down to the bare circuit board and inspected it for visible damage. There wasn’t any, so I used a multi-meter to probe around for anything that didn’t make sense.

When everything checked out to be what I estimated to be correct, I moved to reassembly. I tested each of the fuses with a multi-meter instead of blindly replacing them, and found a couple with high resistance, so I replaced those. Then I moved on to the relays, and all of them tested fine except for the fan clutch relay, which is completely dead. Upon reinstalling the box, I checked that the fan was running, then removed the relay, and found it no different. I’m guessing that it’s designed to fail in such a way that the fan clutch remains engaged if the relay is bad. I ordered a replacement off Ebay ($21, though the dealer wants $35) and it will be here on Wednesday. Among other issues, I found that the 30A micro J-CASE fuse that provides +12V power to the trailer is blown, which explains why I had some of the battery issues a while back. When I couldn’t find the the right size fuse at an auto store or on Amazon, I looked online and found that it’s an odd size, with a GM part number, and that a lot of people seem to recommend carrying spares if you tow a lot. They tend to go often. Again, Ebay to the rescue. Something like $2/ea from a dealer and I ordered two.

With the fuse box ruled out, I almost gave up, but had the idea to disconnect the backup camera that sits inside the tailgate. I’ve moved it around from OEM tailgate -> Fifth Wheel Tailgate -> New Tailgate (different, upcoming post) and figured it might have gotten damaged. Sure enough, when unplugged, the reverse light goes out, and lights operate as expected.

I ordered a replacement camera off a dealer on Ebay for $115, and went to Amazon and spent another $100 on all new 7-Pin connectors and wiring for under the truck. Even though they weren’t the issue, I don’t trust them now that they’ve been filled with water and began to corrode, and would rather play it safe and replace them than lose my trailer breaks while heading down the highway. Those parts should be in this weekend.

—

There is still the issue of an outstanding recall on my truck, which is a software flash to address an air bag deployment issue, and I have a free oil change still owed to me. Once I have the truck back to fully operational, I’ll schedule those and take it in.