VOLVO
ECM-P050400 - Brake Switch A / B Correlation. General Failure Information. No sub type information
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
12 modelsC30 (2007–2013), S40 (2004–2013), S60 (2011–), S80 (2007–), V40 (2013–), V40 Cross Country (2013–), V50 (2004–2013), V60 (2011–), V70 (2008–), XC60 (2009–), XC70 (2008–), XC90 (2003–)
Show models by year and engine (22)
- Volvo C30 (2007–2013)2011–2013Engine D4162T only
- Volvo S40 (2004–2013)2011–2012Engine D4162T only
- Volvo S60 (2011–)2011–2015Engine D4162T only
- Volvo S80 (2007–)2007Engine D5244T4, D5244T5 only
- Volvo S80 (2007–)2008All engines except: B5254T6, B6304T2, B6324S, B8444S
- Volvo S80 (2007–)2009Engine B4204S3, B4204S4, D4204T, D5244T4, D5244T5 only
- Volvo S80 (2007–)2010Engine B4204S3, B4204S4, D4164T, D4204T only
- Volvo S80 (2007–)2011Engine B4204S3, B4204S4, D4164T only
- Volvo S80 (2007–)2012–2015Engine D4162T only
- Volvo V40 (2013–)2013–2015Engine D4162T only
- Volvo V40 Cross Country (2013–)2013–2015Engine D4162T only
- Volvo V50 (2004–2013)2011–2012Engine D4162T only
- Volvo V60 (2011–)2011–2015Engine D4162T only
- Volvo V70 (2008–)2008All engines except: B5254T6, B6304T2, B6324S
- Volvo V70 (2008–)2009Engine B4204S3, B4204S4, D4204T, D5244T4, D5244T5 only
- Volvo V70 (2008–)2010Engine B4204S3, B4204S4, D4164T, D4204T only
- Volvo V70 (2008–)2011Engine B4204S3, B4204S4, D4164T only
- Volvo V70 (2008–)2012–2015Engine D4162T only
- Volvo XC60 (2009–)2009All engines except: B6304T2
- Volvo XC70 (2008–)2008All engines except: B6324S
- Volvo XC70 (2008–)2009Engine D5244T4, D5244T5 only
- Volvo XC90 (2003–)2013–2014Engine D5244T18, D5244T5 only
What does this fault code mean?
The engine control module (ECM) compares the signals from the brake pedal sensor and the brake light switch and checks that they agree. The code is set when the signals do not match, when the circuits are faulty, or when communication with the brake control module (BCM) is disturbed.
Possible causes
- Diagnose the cause in the brake control module (BCM)
- Break or short to ground or supply voltage on the brake light switch wire
- Contact resistance or oxidation in the connections to the brake light switch or brake pedal position sensor
- Brake light switch incorrectly fitted or damaged
- Damaged brake pedal position sensor or a break in the brake pedal sensor circuit
- Low battery voltage
What you can do
- 1Read the codes in the brake control module (BCM) first and repair them, as this code cannot be cleared until the BCM code has been repaired
- 2Check that the fuses for the brake lights and brake pedal are intact, and that the brake light switch is fitted correctly
- 3Check the connectors to the brake light switch and brake pedal sensor for oxidation, loose contacts and chafed wiring
- 4If you have a diagnostic tool, follow the brake pedal signals in live data and check that they change together when you press and release the brake
- 5Use a multimeter to check that the wire to the brake light switch has no break and no contact with ground
- 6If the fault returns, have a workshop with diagnostic equipment check the brake light switch and brake pedal sensor. Do not work on the braking system yourself
Symptoms you may notice4
- Cruise control does not engage
- Warning symbol and message in the display
- The car feels weak or lacks power
- Cruise control does not hold the set speed and disengages
What the fault can affect1
- Cruise control is switched off while the fault is active, or for the rest of the drive cycle in which it was detected
General guidance for car owners. Diagnosis on the car can point to a different cause.