Checking The Rheostat

Checking the rheostat

Checking the instrument lighting




- Ignition on
- Switch on the lighting.
Turn the rheostat control and check that the lighting in the combined instrument panel is functioning. The fault is in the rheostat and not just the climate control unit if the lighting in the combined instrument panel is not working.





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 module are not defective.
Check the rheostat connector and climate control module connector A (30-pin). Check for contact resistance and oxidation.
Check the power supply cable between rheostat terminal #B2/22 and climate control module terminal #A7. Check for an open-circuit.
Remedy as necessary.

Other information:
- To remove the climate control module, see Comfort module Removal and Replacement
- To connect the breakout box, see Connecting the breakout box, climate control module Connecting The Breakout Box
- The signal from the rheostat is a pulsed signal with a frequency of approximately 130 Hz. For other values, see Climate control signal specifications Signal Specification
- For further information about the wiring and terminals, see the Wiring Diagrams Service Manual
- For information about replacing bulbs in the climate control module, see Replacing interior lighting Replacing Interior Lighting
- Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault










Continue - Verification

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





Is the lighting working?

Yes - FAULT FOUND

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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Attempt New Test - Checking the instrument lighting

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