VOLVO
ECM-843C - Starter motor relay. Signal too high
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) monitors the signal wire to the starter motor relay at start. The code is set when the voltage on that wire stays too high for a certain time. The fault may come from a signal wire shorted to supply voltage, a damaged starter motor relay or a damaged control module.
Possible causes
- The signal wire is shorted to supply voltage
- 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 a short to supply voltage; use a multimeter to confirm it has no contact with battery voltage
- 4Repair as needed and check that the code does not come back
- 5If the fault remains after these checks, have a workshop check the starter motor relay and the control module
Symptoms you may notice1
- The engine cannot be started
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.