Diagnostic Trouble Code (DTC) Information CCM-DD21

Condition 

The diagnostic trouble code (DTC) is stored if the climate control module (CCM) detects a short-circuit to supply voltage or ground in LIN bus 2.

A short-circuit to supply voltage or ground in the LIN bus will affect communications and the function of all the components.

The climate control module (CCM) communicates with the damper motors, air quality sensors and seat heating via two LIN buses.

The number of components in LIN bus 2 can vary depending on the vehicle equipment (ECC/MCC and options) and if the vehicle has right-hand drive or left-hand drive.

The following components communicate on LIN bus 2:

• damper motor module (DMM) defroster
• damper motor module (DMM) temperature right (only ECC)
• damper motor module (DMM) recirculation (only on left-hand drive cars)
• air quality sensor (AQS) (only on left-hand drive cars)
• seat heating module (SHM) right.

The diagnostic trouble code (DTC) can be diagnosed in ignition positions I and II.

Substitute Value 

• None.

Possible Source 

• LIN bus 2 short-circuited to supply voltage
• LIN bus 2 short-circuited to ground.

Fault symptom[s] 

• Misting on the windows and/or door mirrors.
• Poor heating in the passenger compartment.
• The front seat heating does not function.
• Poor air quality in the passenger compartment.