Heated Glass Element: Testing and Inspection

Heated Rear Window, Checking

• If there is a condition that prevents the rear window heater from switching on such as a short circuit in the connection to the rear window or an open circuit in the voltage supply to the Climatronic control module (J255) , this will be stored as a fault in the Climatronic control module. Check using vehicle diagnosis, testing and information system VAS 5051 in the "Guided Fault Finding" function.

• If the voltage measured at the Energy Management Control Module (J644) terminal 30 falls below a value stored in the Energy Management Control Module, the rear window defogger is either switched off completely or its output is reduced to relieve the load on the generator (the Climatronic control module reduces the duty cycle activation from 100% to between 0 and 90%). Check using Vehicle Diagnosis, Testing and Information System VAS 5051 in the "Guided Fault Finding" function.

• If heated rear window must be switched off due to insufficient voltage, indicator lamp in heated rear window button on Climatronic control module remains switched on, however if switch-off is to last longer than approximately 150 seconds, Climatronic control module switches off the indicator lamp.

• Measuring value block of the Climatronic control module indicates that heater of Heated Rear Window is switched on or why no activation is occurring despite a request. Check using Vehicle Diagnosis, Testing and Information System VAS 5051 in "Guided Fault Finding" function.

• The function test for the rear window defogger is described in A/C system Guided Fault Finding in the Vehicle Diagnosis, Testing and Information System VAS 5051 in "Guided Fault Finding".

• The heated rear window stays switched on at outside temperatures up to 0°C (32 °F) until ignition is switched off (heated rear window can be switched manually at anytime). If temperature becomes greater than 0 °C (32 °F)during a driving period, switch-off of Heated Rear Window occurs after operating time stored in the Climatronic control module has elapsed (approximately 10 minutes).

• Once the operated time (approximately 10 minutes) stored in the Climatronic control module has elapsed, the heated rear window can be switched off automatically by the Climatronic control module when the exterior temperature is greater than 0° C (32 °F) (activation time depends on the code and the Climatronic control module version). Refer to Vehicle Diagnosis, Testing and Information System VAS 5051 in "Guided Fault Finding".