VOLVO
ECM-0686 - System relay. Signal too low
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 (17)
- Volvo C30 (2007–2013)2007–2009Engine B4184S11, B4184S8, B4204S3, D4204T only
- Volvo C30 (2007–2013)2010Engine B4184S11, B4184S8, B4204S3, B4204S4, D4204T only
- Volvo C30 (2007–2013)2011–2013Engine B4204S3, B4204S4 only
- Volvo C70 (2006–2013)2008Engine D4204T only
- Volvo C70 (2006–2013)2009–2010Engine D4204T only · Transmission MMT6, MPS6 only
- Volvo S40 (2004–2013)2004Engine D4204T, D4204T2 only
- Volvo S40 (2004–2013)2005Engine B4184S11, D4204T, D4204T2 only
- Volvo S40 (2004–2013)2006Engine B4184S11, B4184S8, D4204T, D4204T2 only
- Volvo S40 (2004–2013)2007–2009Engine B4184S11, B4184S8, B4204S3, D4204T only
- Volvo S40 (2004–2013)2010Engine B4184S11, B4184S8, B4204S3, B4204S4, D4204T only
- Volvo S40 (2004–2013)2011–2012Engine B4204S3, B4204S4 only
- Volvo V50 (2004–2013)2004Engine D4204T, D4204T2 only
- Volvo V50 (2004–2013)2005Engine B4184S11, D4204T, D4204T2 only
- Volvo V50 (2004–2013)2006Engine B4184S11, B4184S8, D4204T, D4204T2 only
- Volvo V50 (2004–2013)2007–2009Engine B4184S11, B4184S8, B4204S3, D4204T only
- Volvo V50 (2004–2013)2010Engine B4184S11, B4184S8, B4204S3, B4204S4, D4204T only
- Volvo V50 (2004–2013)2011–2012Engine B4204S3, B4204S4 only
What does this fault code mean?
The ECM watches the system relay. It sets the code when the signal from the relay is too low, or when the relay does not release within the expected time. The fault may show at start attempts, when the engine does not start or turn over and the relay gives no click.
Possible causes
- Signal wire shorted to earth
- Signal wire shorted to voltage
- Damaged system relay
What you can do
- 1Check the battery voltage and condition, and that the battery terminals are tight
- 2Check that the generator is charging the battery
- 3Check the connectors at the engine control module and the system relay for contact resistance and oxidation
- 4With the ignition off, check the signal wire for a short to earth
- 5If no fault is found and the fault remains, a new system relay can be tried; a workshop should fit it
Symptoms you may notice2
- Starting problems, with the engine not starting or turning over
- No click from the relay at start attempts
General guidance for car owners. Diagnosis on the car can point to a different cause.