2018 SCAB Brake Light Switch Issues

[CO_Escape Pod]

I have a 2018 SCAB with under 20k miles and for the second time in less than 3k miles I have burned out a brake light switch and some fuses causing it to throw 'hill descent control' and 'hill start assist' disabled warnings, along with the airbag light. It's only $30 in parts to fix but not something I feel like dealing with long term... just seeing if anyone has an idea what could be the underlying problem before I take it to the stealership for troubleshooting.... thanks!

Only mods are deavers, geisers, and a topper

 

[Dustan]

Does the topper have a wired brake light?

 

[FordTechOne]

Does the topper have a wired brake light?

Exactly what I was going to ask.

 

[CO_Escape Pod]

Exactly what I was going to ask.

It sure does... I'll have to trace those wires and look for a short. I figured that would have burned out the fuse faster but it's a good place to start. Thanks!

 

[FordTechOne]

It sure does... I'll have to trace those wires and look for a short. I figured that would have burned out the fuse faster but it's a good place to start. Thanks!

It sounds like it’s wired incorrectly. If you tap into the brake pedal position switch (stop lamp switch) you will damage the switch and/or set DTCs. The only acceptable circuit to use is Pin 7 of C2280G of the BCM, which on your truck should be an empty cavity. You would need to install a pin and circuit and then use that to trigger a relay, which will operate the stop lamp on the topper. You will also need a diode before the relay to prevent feedback voltage to the BCM and PCM.