VOLVO
ECM-P050429 - Brake Switch A / B Correlation. General Signal Failures. Signal signal invalid
System
Engine Control Module (ECM)
Volvo models this fault code applies to
This fault code has different meanings depending on model, model year or engine. Select the meaning that applies to your car.
Applies to the following models:
14 modelsC30 (2007–2013), C70 (2006–2013), S40 (2004–2013), S60 (2011–), S80 (2007–), V40 (2013–), V40 Cross Country (2013–), V50 (2004–2013), V60 (2011–), V60 Cross Country (2015–), V70 (2008–), XC60 (2009–), XC70 (2008–), XC90 (2003–)
Show models by year and engine (47)
- Volvo C30 (2007–2013)2011–2013Engine D5204T, D5204T5 only
- Volvo C70 (2006–2013)2011Engine D5204T, D5204T5 only
- Volvo C70 (2006–2013)2012–2013All engines except: B5254T7
- Volvo S40 (2004–2013)2011–2012Engine D5204T, D5204T5 only
- Volvo S60 (2011–)2011Engine B6304T4, D5204T2, D5244T10 only
- Volvo S60 (2011–)2012Engine B6304T4, D5204T3, D5244T11, D5244T15 only
- Volvo S60 (2011–)2013All engines except: B4164T, B4164T2, B4164T3, B4204T7, D4162T
- Volvo S60 (2011–)2014Engine B5204T8, B5204T9, B5254T12, B5254T14, B6304T4, D5204T3, D5204T7, D5244T11, D5244T15 only
- Volvo S60 (2011–)2015All engines except: B4164T, B4164T2, B4164T3, B4204T10, B4204T11, B4204T12, B4204T15, B4204T9, D4162T, D4204T5
- Volvo S80 (2007–)2007Engine B6324S, B8444S only
- Volvo S80 (2007–)2008Engine B6304T2, B6324S, B8444S only
- Volvo S80 (2007–)2009Engine B6304T2, B6324S, B8444S, D5244T10 only
- Volvo S80 (2007–)2010Engine B6304T2, B6324S, B6324S2, B8444S, D5244T10, D5244T14, D5244T19 only
- Volvo S80 (2007–)2011Engine B6304T4, B6324S4, B6324S5, B8444S, D5204T2, D5244T10 only
- Volvo S80 (2007–)2012Engine B6304T4, B6324S4, B6324S5, D5204T3, D5244T11, D5244T15 only
- Volvo S80 (2007–)2013All engines except: B4164T, B4164T2, B4204T6, B4204T7, D4162T
- Volvo S80 (2007–)2014Engine B5254T12, B5254T14, B6304T4, B6324S4, B6324S5, D5204T3, D5204T7, D5244T11, D5244T15 only
- Volvo S80 (2007–)2015Engine B6304T4, B6324S4, B6324S5, D5204T3, D5244T15 only
- Volvo V40 (2013–)2013–2014Engine B5204T8, B5204T9, B5254T12, B5254T14 only
- Volvo V40 (2013–)2015Engine B5204T8, B5204T9 only
- Volvo V40 Cross Country (2013–)2013–2015Engine B5204T8, B5204T9, B5254T12, B5254T14 only
- Volvo V50 (2004–2013)2011–2012Engine D5204T, D5204T5 only
- Volvo V60 (2011–)2011Engine B6304T4, D5204T2, D5244T10 only
- Volvo V60 (2011–)2012Engine B6304T4, D5204T3, D5244T11, D5244T15 only
- Volvo V60 (2011–)2013All engines except: B4164T, B4164T2, B4164T3, B4204T7, D4162T
- Volvo V60 (2011–)2014All engines except: B4164T, B4164T2, B4164T3, B4204T11, B4204T12, B4204T15, B4204T7, B4204T9, D4162T, D4204T5
- Volvo V60 (2011–)2015All engines except: B4164T, B4164T2, B4164T3, B4204T11, B4204T12, B4204T15, B4204T9, D4162T, D4204T5
- Volvo V60 Cross Country (2015–)2015
- Volvo V70 (2008–)2008Engine B6304T2, B6324S only
- Volvo V70 (2008–)2009Engine B6304T2, B6324S, D5244T10 only
- Volvo V70 (2008–)2010Engine B6304T2, B6324S, B6324S2, D5244T10, D5244T14, D5244T19 only
- Volvo V70 (2008–)2011Engine B6304T4, B6324S5, D5204T2, D5244T10 only
- Volvo V70 (2008–)2012Engine B6304T4, B6324S5, D5204T3, D5244T11, D5244T15 only
- Volvo V70 (2008–)2013All engines except: B4164T, B4164T2, B4204T7, D4162T
- Volvo V70 (2008–)2014All engines except: B4164T, B4164T2, B4204T11, B4204T7, D4162T, D4204T5
- Volvo V70 (2008–)2015All engines except: B4164T, B4164T2, B4204T11, D4162T, D4204T5
- Volvo XC60 (2009–)2009Engine B6304T2 only
- Volvo XC60 (2009–)2010All engines except: B4204T6
- Volvo XC60 (2009–)2011–2012All engines except: B4204T6, B4204T7
- Volvo XC60 (2009–)2013All engines except: B4204T7
- Volvo XC60 (2009–)2014–2015All engines except: B4204T10, B4204T11, B4204T12, B4204T15, B4204T7, B4204T9, D4204T5
- Volvo XC70 (2008–)2008Engine B6324S only
- Volvo XC70 (2008–)2009Engine B6304T2, B6324S only
- Volvo XC70 (2008–)2010–2013
- Volvo XC70 (2008–)2014–2015All engines except: B4204T11, D4204T5
- Volvo XC90 (2003–)2007–2010Engine B6324S only
- Volvo XC90 (2003–)2011–2014Engine B6324S5 only
What does this fault code mean?
The engine control module (ECM) checks the brake light switch by comparing its signal with the brake pedal position, which the brake control module (BCM) sends over the CAN network. The code is set when the two signals show different brake pedal positions on several occasions. An incorrect or invalid signal from either position switch may be the cause.
Possible causes
- Diagnose the cause in the brake control module (BCM)
- Contact resistance or oxidation in the connections to the brake light switch
- Contact resistance or oxidation in the connections to the brake pedal switch
- Break in the signal wire or short to ground
- Damaged brake light switch or brake pedal switch
- Brake light switch incorrectly fitted
What you can do
- 1Read the codes in the brake control module (BCM) and the central electronic module (CEM) first, and repair them
- 2Check that the brake light switch is fitted correctly and that the brake pedal position sensor is seated properly. Also check that the fuses are intact
- 3Check the connectors of the brake light and brake pedal switches for oxidation, loose contacts and chafed or broken wires
- 4If you have a diagnostic tool, follow the brake pedal positions in live data and check that they agree when the pedal is pressed several times
- 5After the repair, read the code and check that it does not come back when the brakes are used
- 6Do not work on the braking system yourself; have a workshop carry out the checks that need diagnostic equipment
Symptoms you may notice5
- Warning symbol and message in the display
- Cruise control does not work at all
- Cruise control does not hold the set speed and disengages
- Autostart does not work
- The engine does not start, either sometimes or always
What the fault can affect2
- Autostart is blocked and automatic engine start/stop is switched off
- Cruise control is switched off while the fault is active, or for the drive cycle in which it was detected
General guidance for car owners. Diagnosis on the car can point to a different cause.