Ford F-250 Trailer Brake Controller Mystery

Over the last couple of years I have been trying to resolve several mysteries related to my F-250. I love the truck, but some times the trouble shooting is a complete mystery. I find that many of the Ford Forums carry the same questions as I have, but lack correct answers. Even the dealerships merely guess at how to fix the problems. At $75 per hour, I don't want to pay them to guess what is wrong with my truck. 

 I have recently taken on a battle of the Service AdvanceTrac/Downhill Assist issue. What was seemingly unrelated is that the on-board trailer brakes also quit working. Additionally, the red BRAKE light showed up and I got a "Service Brake System" warning. Basically, my dashboard looked like a Christmas tree. Fortunately all of these issues are related to each other, even though they did not show up at the same time. 

Issue #1 - Bad Driver Side Hub

When a Ford hub goes bad, it fires off all sorts of warnings, including ABS Lights, AdvanceTrac lights and the Brake Light. If the hub is bad, its pretty easy to chase down, because they are not quiet. I was able to get the hub replaced which resolved the Brake light issue. 

Issue # 2 - Abs Speed Sensor 

When the driver side hub was replaced the speed sensor is also replaced. It turns out that the passenger speed sensor had an issue as well. I pulled the wheel and found that the harness had been compromised and was shorting out. I was able to replace the harness myself (it only takes about 30 minutes and can be completed by a novice). Once I replaced the harness, I cleared the codes with Forscan and was good to go. 

CAUTION: I had to do this twice because I did not make sure that the harness was clear of other moving parts. Within a week, the harness shorted out and I was pulling the tire off again. This time I threaded the wire correctly and away from moving parts. 

 By replacing the ABS speed sensor, I was able to resolve all of the issues I was having related to AdvanceTrack, Stability Control and the trailer brake controller started working correctly again.