Checking Rheostat

Checking rheostat

Checking instrument lighting




- Ignition on.
- Turn on lighting.
Turn the rheostat control and check that the lighting in the combined instrument panel is functioning. If the lighting in the combined instrument panel is not working, this indicates that the fault is in the rheostat and not just the climate control unit.





Does the lighting in the combined instrument panel function normally?

Yes - Checking, cables and components

No - No Fault Found

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Checking, cables and components
Check that the bulbs in the climate control panel are not defective.
Check the climate control connector(control module connector) for contact resistance and oxidation according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Check cable for power supply between rheostat terminal 4 and control module (ECC #A16) (MCC #B18) for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Remedy as necessary.

Other information:
- To disconnect ECC control module, refer to Replacing ECC control module Removal and Replacement.
- To disconnect MCC control module, refer to Replacing or adjusting control cables / mechanical rear section and control panel / front section (Manual climate control / STANDARD) Service and Repair.
- Connection of breakout box to ECC control module, refer to Connection of breakout box ECC Connection of Breakout Box ECC.
- Connection of breakout box to MCC control module, refer to Connection of breakout box MCC Connection of Breakout Box MCC.
- The signal from the rheostat is a pulsed signal with a frequency of approximately 125 Hz. For other values, see Signal specification ECC Signal Specification ECC and Signal descriptions MCC Signal Descriptions MCC.


















Continue - Verification

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Verification




- Ignition on.
- Turn on lighting.
Turn the rheostat control and check that the lighting in the climate control panel is functioning.





Is the lighting working?

Yes - Fault has been remedied

No - Fault-tracing information

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Fault-tracing information




Information

Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed.
Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.

Do you want to exit fault-tracing?

Yes - Exit fault-tracing

No - Attempt New Test


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