2019 2.7 XL 44k miles

I got a see manual, parking break error, service advancetrac error, ABS error, and a yellow wrench as well.

Pulled codes:

• P1935 - Brake switch/sensor signal. For some reason I can’t find a lot about this online, weirdly little information regarding this code.
• U0121 - Lost Communication with ABS Control Module
• U1012 - Invalid internal control module monitoring data received from abs system

Turned truck back on and all went away including the wrench. It’s also been raining a bit here. I had a pool of water in the passenger side floor and side rail under the plastic step as well. That is cleaned up and dry now.

 

Well, you see, a more in depth description of the code tells the story.
PCM monitors the Brake pedal position for signal from the ABS module, as missing within a short time interval..
Then you begin to see the possible relationship.
May not be the Brake Sensor, but a missing signal from the ABS, for some reason.
Good luck.

 

Thanks I updated the post with additional codes I pulled

 

bump

 

Well it looks like you have a leak on the passenger side (seems to be a known issue) and the ABS module most likely got wet which caused the codes and wrench light.

 

That leak was caused my the AC drain and I have since installed the fix which is a 90 degree elbow seen here


Do you really think it got to my ABS module in the engine bay? Its on the driver side isnt it?

 

You know what, that's my bad, for some reason I thought the ABS module is located in the passenger side footwell. Please disregard my last comment.

There is a fuse box there though, maybe that has something to do with your issue.

 

The BPP (Brake Pedal Position) Switch has two separate switching circuits as shown below. Both circuits are monitored by the PCM. When the switch is functioning properly both the BPP and BPS inputs to the PCM change at the same time. The PCM then sends a signal to the ABS module over the HS1-CAN bus. If there is a discrepancy between BPP and BPS the PCM does not send a valid brake pedal position signal to the ABS module this causes the "U" codes. If your stop lamps are still functioning, then the problem is with the BPS side of the switch. If your brake lamps are not working, it is either BCM Fuse-14 (10 A), the BPP side of the switch, or a wiring issue such as ground. Knowing that you had water intrusion from the AC drain on the passenger side of the cabin where the BCM is located, the problem was probably the BPP circuit. Once it dried out everything started working properly. You should check all the connectors to the BCM for water intrusion and any signs or corrosion. Dry and clean any problems. Your ABS module did not get any water intrusion from this leak and should be okay.

 

Thanks for that. My brake lights work. Also, my entire engine bay is bone dry and dusty as well. Im not sure if water is still suspected knowing this

Today none of the 3 codes came back and it was raining all day as well. I will disconnect all connections to the BCM and check for any abnormalities. Thanks Ill update tomorrow

 

Passenger door sill is still full of water. Its been raining, I did the AC drain 90 degree elbow fix but the water was there before I added the elbow. Any idea how to get it out of there? Shop vac? Thanks