P0571 and Brake failure - stop safely
 

I bought my 2004 XC70 with inoperative info lighting. After I changed the lighting switch assembly, the "Brake failure stop safely" warning became visible. The check-engine and ABS lights were not on but the P0571 code for the brake pedal sensor was pending. Other faults include an odometer that doesn't move very often, a trip odometer that only displays dashes, inoperative cruise control, non-functioning ABS (of course) and failed all-wheel drive.

I installed a spare brake-position sensor in the master cylinder to rule it out; nothing changed. Either both were good or both were bad, so I didn't learn anything. The service records indicate that the brake module was replaced three years ago but the multiple issues do indeed suggest a defective brake module.

Unfortunately, I don't have a scanner that displays the manufacturer-specific codes that I desperately need. (That's why I asked for opinions about the Autophix ES610 scanner.) Until I have a capable scanner, I'm dead in the water, but I'll update as this story unfolds because the symptoms are very common.

Unfortunately, a drunk driver made this repair unnecessary.

Just for the sake of trying out my new iCarsoft i906, I scanned all of the modules and, to my surprise, there were no codes stored in the brake control module. The only indication of a brake system issue was the P0571 (OBD2) and in the engine control module: ECM 9400 ("brake switch A circuit"). When I previously changed the brake position sensor, I didn't have the capability of clearing the code in the ECM. Not that I have that capability, the car cannot be driven because it is a bloody mess. It would be good to know whether I have a good spare BCM or not but making the car driveable again would be a lot of work.