VOLVO
ECM-0685 - System relay. Signal missing
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:
4 modelsC30 (2007–2013), C70 (2006–2013), S40 (2004–2013), V50 (2004–2013)
Show models by year and engine (10)
- Volvo C30 (2007–2013)2007Engine D4204T only
- Volvo C30 (2007–2013)2008–2010Engine D4204T only · Transmission MMT6, MPS6 only
- Volvo C70 (2006–2013)2008Engine D4204T only
- Volvo C70 (2006–2013)2009–2010Engine D4204T only · Transmission MMT6, MPS6 only
- Volvo S40 (2004–2013)2004–2006Engine D4204T, D4204T2 only
- Volvo S40 (2004–2013)2007Engine D4204T only
- Volvo S40 (2004–2013)2008–2010Engine D4204T only · Transmission MMT6, MPS6 only
- Volvo V50 (2004–2013)2004–2006Engine D4204T, D4204T2 only
- Volvo V50 (2004–2013)2007Engine D4204T only
- Volvo V50 (2004–2013)2008–2010Engine D4204T only · Transmission MMT6, MPS6 only
What does this fault code mean?
The ECM checks the signal wire to the system relay coil and sets the code when the signal is missing. The fault shows at start attempts: the engine does not start or turn over, and no click is heard from the relay.
Possible causes
- Poor connections, contact resistance or oxidation at the terminals
- Break in the supply to the system relay coil
- Break in the signal wire
- Damaged system relay
What you can do
- 1Check the battery voltage and condition, since weak voltage can cause the fault
- 2Check that the generator is charging the battery
- 3Check the connectors at the engine control module and at the system relay for contact resistance and oxidation
- 4Use a multimeter to check the signal wire for an open circuit
- 5If no fault is found and the fault remains, a new system relay can be tried; a workshop should replace it
Symptoms you may notice3
- The engine does not start
- The engine does not turn over at start attempts
- No click from the relay when it should engage
General guidance for car owners. Diagnosis on the car can point to a different cause.