Component Tests and General Diagnostics

Checking The Supply Voltage/ground Terminal

Checking the power supply and ground terminals Power supply, climate control module (CCM)

The climate control module (CCM) is powered via a power input on the control module.

Power input terminal #1 (#25) is +15-supplied via a relay and fuse from the central electronic module (CEM). In the event of an open-circuit, climate control functions cannot be activated.

Checking the power supply

Check the power supply cable from the central electronic module (CEM) to climate control module (CCM) terminal #1 (#25). Check for an open-circuit. Check for loose connections. Check for contact resistance. Check for oxidation. Check the fuse. The voltage must be approximately battery voltage.

Ground terminal, climate control module (CCM)

The climate control module (CCM) has a ground input. The ground input from the control module is power ground and is connected to the ground terminal in the car body.

Checking the ground terminal

Check the ground lead between climate control module (CCM) terminal #16 (#40) and the ground terminal. Check for an open-circuit. Check for loose connections. Check for contact resistance. Check for oxidation. With the ignition on, the drop in voltage between the ground connection and the ground terminal for the climate control module (CCM) must not be greater than 0.5 V.

Remedy as necessary.

Other information
- Connecting the breakout box
- Signal specification
- See the relevant wiring diagram for information about circuit and ground terminals in the bodywork
- Checking wiring and terminals: Contents