2004 XC90 ABS & brake light help
 

I own a 04 XC90 and the other day while I was driving the ABS light and "BRAKE" light came on along with a message that said "Brake Failure, stop Safely". The brake fluid is good and the pedal feels nice a firm. It stops well also. I pulled code# P0571 from the computer. I came to change out the brake sensor to the left of the master cyl. on the booster last night and it didn't do a thing. Does anyone have a fix for this. I'm a mechanic so I can do the work, I just don't know where to go with this.

Thanks Guys!!

I believe that usually is the code for it, you erased them I'm sure. Connector oxidation, not usually but...

may want to try and pull the negative cable 20min. if all else fails, never know.

Oxidation on the wheel speed sensor connectors?

There are 3 states: signal high, incorrect, or missing. Fault tracing is misleading because it may have nothing to do with the switch on the brake pedal, rather it is the one in the booster. It may have to be scanned by Volvo for other codes.


Oxidation in the connector for the sensor.





Possible source

• Signal too high:
• Look for the cause of the malfunction in the brake control module (BCM) and in the central electronic module (CEM).

• Incorrect signal:
  Malfunction in brake control module (BCM) or in central electronic module (CEM).
  Contact resistance or oxidation in the connections between the engine control module (ECM) and the brake light switch.
  Open circuit in the voltage feed to the brake light switch.
  Open circuit or short-circuit to ground or voltage in the cable for the brake light switch.
  Incorrectly installed brake light switch.
  Incorrectly adjusted brake light switch.
  Water in the connectors.
• Damaged brake light switch.

• Signal missing:
• Look for the cause of the malfunction in the brake control module (BCM) and in the central electronic module (CEM).

1 of the things you can do is to reset the brake light switch on the brake pedal. just push down the pedal & push the sensor down, release the pedal. that will adjust the brake light switch again. but what scan tools u used to get that code?? cuz that's not a volvo code.

Its the standard one, you have to convert it to Volvo, I believe it is a ECM-9400.

ecm-9400 signal too high?? too low?? missing??

Yeah, thats what im trying to figure out but his scanner doesnt have all that like VIDA.

2004 XC90 ABS & brake light help
 

I have a 2004 S80 with the same issue. I found that if I turn the ignition on so all the dash lights are on, pump the brake a few times and hold the brake down while starting the car. This will clear the lights and the "brake falure Brake Safely" from the menu untill I turn the car off and let it sit for a few minutes.