Windshield Defogger

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The Windshield Defogger Control Module -J505- is activated by the front Air Conditioning (A/C) display control head, the Climatronic Control Module -J255- via the data bus. For this purpose, the request is first sent via the data bus to the Data Bus On Board Diagnostic Interface -J533- and is then relayed to the Comfort System Central Control Module -J393-. The Comfort System Central Control Module -J393- then relays the request to the Windshield Defogger Control Module -J505- which activates the heating of the Windshield Defogger -Z2- see Vehicle Diagnostic Tester in the "Guided Fault Finding " function and Wiring Diagram.
The activation of the Windshield Defogger Control Module -J505- is displayed in the read "measured values" function of the Guided Fault Finding of the Climatronic Control Module -J255- see Vehicle Diagnostic Tester.
The "read measured values" function of the Guided Fault Finding of the Comfort System Central Control Module -J393- and the front A/C display control head, the Climatronic Control Module -J255-, displays that a request is present and why this is not being implemented if applicable see Vehicle Diagnostic Tester.
Check the activation of the windshield defogger, refer to Vehicle Diagnostic Tester In the "Guided Fault Finding " function.
Windshield defogger functionality, refer to WINDSHIELD DEFOGGER FUNCTIONALITY .
If the resistance value calculated by the Comfort System Central Control Module -J393- (displayed as measured values) is greater than 2.4 ohms or less than 1.5 ohms, check the wire connection from the Windshield Defogger Control Module -J505- to the Windshield Defogger -Z2- for short circuit or contact resistance see Vehicle Diagnostic Tester in the "Guided Fault Finding " function.
If the resistance value measured by the Comfort System Central Control Module -J393- is greater than 3.4 ohms or less than 1.4 ohms, the Comfort System Central Control Module -J393- does not activate the Windshield Defogger Control Module -J505- or does not activate the heating of the Windshield Defogger -Z2- see Vehicle Diagnostic Tester in the "Guided Fault Finding " function.