VOLVO
CCM-DD21 - LIN bus 2. Signal too high/Signal too low
System
Climate Control Module (CCM)
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:
5 modelsC30 (2007–2013), C30 Electric (2011–2013), C70 (2006–2013), S40 (2004–2013), V50 (2004–2013)
What does this fault code mean?
The climate control module (CCM) has found that LIN bus 2 is short-circuited, either to supply voltage or to ground. This disrupts communication with all the components on the bus, such as the damper motors, the air quality sensor and the seat heating. The symptoms may therefore be several.
Possible causes
- LIN bus 2 is short-circuited to supply voltage
- LIN bus 2 is short-circuited to ground
What you can do
- 1Check that the fuses are intact
- 2Check that the connectors on LIN bus 2 are secure and free from corrosion
- 3Check with a multimeter that the LIN bus 2 wires have no contact with ground (the bodywork) when the connectors are disconnected
- 4Check with a multimeter that the LIN bus 2 wires have no voltage when the connectors are disconnected and the ignition is on
- 5If you have a diagnostic tool, disconnect the components one at a time and see when the code stops returning
Symptoms you may notice4
- Mist on the windows and/or the outside mirrors
- Poor heating in the cabin
- Front seat heating does not operate
- Poor air quality in the cabin
General guidance for car owners. Diagnosis on the car can point to a different cause.