Heated Rear Window Z1, Checking

Heated Rear Window Z1, Checking

NOTE:
- Situations preventing activation of heated rear window (short circuit in connection to rear window, open circuit in power supply to Climatronic Control Module J255) are stored as DTCs in Climatronic Control Module J255 "Guided Fault- Finding" function of Diagnostic Operation System VAS 5051.
- If voltage measured at Energy Management Control Module J644 at terminal "30" drops below value stored in Energy Management Control Module J644, heated rear window is completely deactivated at present (or power is reduced) to relieve load on alternator (electronics system of Climatronic Control Module J255 reduces actuation duty cycle from 100% to 90....0%) "Guided Fault-Finding" function of Diagnostic Operation System VAS 5051.
- If heated rear window has to be deactivated on account of undervoltage, indicator lamp in button for heated rear window in Climatronic Control Module J255 remains on. However if deactivation lasts longer than approx. 150 seconds, Climatronic Control Module J255 switches off indicator lamp.
- Measured value block of Climatronic Control Module J255 shows that rear window heating is on or indicates why there is no actuation in spite of corresponding request (display groups "023", "033", "034" and "035") "Guided Fault-Finding" function of Diagnostic Operation System VAS 5051.
- Checking actuation of heated rear window operation is described in Guided Fault-Finding for air conditioner "Guided Fault-Finding" function of Diagnostic Operation System VAS 5051.
- At ambient temperatures below 0 degree C, heated rear window remains switched on until ignition is switched off (manual deactivation is possible at any time). If temperature during a driving cycle rises above 0 degree C, heated rear window is deactivated on completion of operating period stored in Climatronic Control Module J255 (approx. 10 minutes).
- At ambient temperatures above 0 degree C, heated rear window is deactivated automatically on completion of operating period stored in Climatronic Control Module J255 (approx. 10 minutes) by Climatronic Control Module J255 (e.g. on vehicles with standard glass, actuation time is governed by coding of Climatronic Control Module J255 Measuring Value Blocks (Function 08) Reading measured value block, display group "050").