VOLVO
ECM-843D - Starter motor relay. Signal too low
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
4 modelsC30 (2007–2013), C70 (2006–2013), S40 (2004–2013), V50 (2004–2013)
Show models by year and engine (9)
- Volvo C30 (2007–2013)2007Engine B5254T3 only
- Volvo C30 (2007–2013)2008–2013Engine B5254T7 only
- Volvo C70 (2006–2013)2006–2007Engine B5254T3 only
- Volvo C70 (2006–2013)2008–2013Engine B5254T7 only
- Volvo S40 (2004–2013)2006–2007Engine B5254T3 only
- Volvo S40 (2004–2013)2008Engine B5254T3, B5254T7 only
- Volvo S40 (2004–2013)2009–2012Engine B5254T7 only
- Volvo V50 (2004–2013)2006–2007Engine B5254T3 only
- Volvo V50 (2004–2013)2008–2012Engine B5254T7 only
What does this fault code mean?
The engine control module (ECM) compares the voltage on the starter motor relay signal wire with a limit value at start. If the voltage stays below the limit for a certain time, the control module registers a fault and sets the code. The cause may be a short to ground or an open circuit in the signal wire, a faulty relay, an open circuit in the supply to the starter motor or a damaged control module.
Possible causes
- The signal wire is shorted to ground
- Open circuit in the signal wire
- Open circuit in the supply to the starter motor
- Damaged starter motor relay
- Damaged control module
What you can do
- 1Read the code, clear it and check that it does not return at the next start
- 2With the ignition off, check the connectors to the starter motor relay for loose fit, oxidation and contact resistance
- 3Check the signal wire for breaks, and use a multimeter against ground (the body) to confirm it is not shorted
- 4Check that the starter motor relay is undamaged and seated properly
- 5If the fault remains after these checks, have a workshop check the supply to the starter motor and the control module
Symptoms you may notice1
- The engine does not start
What the fault can affect1
- Only manual starting is possible
General guidance for car owners. Diagnosis on the car can point to a different cause.