had original ABS module rebuilt, but still having the same issues, so today drove to a dismantler and bought a used module and still having the same issues. So I am thinking maybe the issue is not the module.

Codes pulling P0571 (Brake Switch A Circuit) and P0504(Brake Switch A/B Correlation). Other symptoms ABS, skid and brake lights are all on along with brake failure stop carefully warning in the messages screen. trip odometer is dashes and cruise control does not work.

I am thinking there is a possibility of the wheel sensors, but was wondering how to test these to see if they are good or not as well as testing the brake pedal sensor on the brake booster.

Any help is greatly appreciated.

Thank you.

 

Mine is doing the same thing...took it to someone with the proper Volvo code reader and it came up that the left hand abs sensor was faulty. Will replace both at the same time. Still drives great and no issues with the brakes working.

 

Did replacing the abs sensors get rid of your codes ?

 

Have them check your brake pedal sensor too

 

Is there a way to check it myself cause there isn't a volvo garage or any repair shop that will have have one of the fancy volvo scan tools that is anywhere near me.

 

Only if you have a scanner. I was able to see the voltage going to the sensor, the distance the plunger was moving, as well as it turn ON/OFF when the brake pedal was pressed. It looks like a bitch to get out though and I havent found anyone that made a video about its removal. I found out that theres a C clip holding it in but you cant see it and you have to do it by feel. If you look at the brake pedal, theres 2 sensors. The blue and white one twists out but as far as I know, the black one is held in by a C clip.