Checking Rear Windshield Heating

Checking the rear windshield heating

Fault-tracing information
Rear windshield heating is supplied with power via a relay positioned in the integrated relay/fusebox in the engine compartment.
Reasons for the rear windshield heating not working can include:
- Burnt out fuse
- Damaged relay
- Defective switch
- Open-circuit in the signal cable
- Open-circuit in the heating loop.

Continue - Checking components

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Checking components
Check that the following components are intact:
- Rear windshield heating fuse
- Rear windshield heating switch.

Checking the relay
Check that the rear windshield heating relay is correctly installed.
Also check the relay terminal, in particular terminal #5. Check for a short-circuit to ground.
Check the function of the rear windshield heating relay. Activate and deactivate the relay a number of times. The relay is functioning if there is a clicking sound when the relay is activated and deactivated.
Click the VCT2000 symbol to activate and deactivate the relay.
Remedy as necessary.

Other information
- Checking wiring and terminals Checking Wiring and Terminals





Was a fault detected?

Yes - Verification

No - Checking the components and wiring

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Checking the components and wiring
Check the signal cable between the central electronic module (CEM) and the rear windshield heating. Check for an open-circuit. Check for a short-circuit to ground.
Take readings between:
- Central electronic module (CEM) terminal #C28 (#28) and rear windshield heating connector.

Checking the rear windshield
Measure the resistance in the heating loop.
Normal resistance at +20°C for:
- 4-doors, approximately 0.63 ohms.
- 5-doors, approximately 0.76 ohms.
Remedy as necessary.

Other information
- Connecting the breakout box Connecting the Breakout Box, Central Electronic Module (CEM)
- Checking wiring and terminals Checking Wiring and Terminals

Continue - Replacing the component

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Replacing the component
The fault was probably caused by an open-circuit in the heating loop.
Replace the rear windshield.

Other information
- Tailgate Service and Repair

Continue - Verification

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Verification




Verification

Hint: After carrying out the repair, check that the fault has been remedied.








- Ignition off
- Reinstall the connectors, components etc.
- Ignition on.
Click the VCT2000 symbol to activate and deactivate the relay.
A click should be heard from the relay.
Check that the function is OK.





Is the function OK?

Yes - VERIFIED

No - VERIFICATION FAILED

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VERIFIED - FAULT FOUND

VERIFICATION FAILED - Fault-tracing information

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Fault-tracing information

Attempt New Test - Fault-tracing information

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