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Checking actuation of seat heating (optional extra) > < Vehicles with automatically controlled air conditioner

A3 Mk2

Vehicles with manually controlled air conditioner
Vehicles with manually controlled air conditioner
Actuation by air conditioning system control unit -J301-
   
t  On pressing the button -E- with the ignition switched on, the onboard supply control unit -J519- is actuated (by the air conditioning system control unit -J301- via the data bus). As soon as the onboard supply control unit -J519- activates the heated rear window (only with engine running), the lamp in the button -E- lights (-J519- transmits feedback via the data bus). The heated rear window is switched off on pressing the button -E- again and on switching off the ignition. → Current flow diagrams, Electrical fault finding and Fitting locations → Owner's manual
t  At present, if the voltage measured at the onboard supply control unit -J519- at terminal „30“ drops below a value stored in -J519-, actuation of the heated rear window -Z1- is fully deactivated (or power is reduced) to relieve the load on the alternator -C- → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051.
t  The heated rear window -Z1- is only actuated by the onboard supply control unit -J519- with the engine running. When the engine is stopped, there is no actuation and no feedback from -J519-, the LED in the button -E- does not light or goes out again shortly after actuation. → Owner's manual → Current flow diagrams, Electrical fault finding and Fitting locations
t  If the heated rear window -Z1- has to be briefly deactivated by the onboard supply control unit -J519- on account of undervoltage, the indicator lamp in the button for the heated rear window -E- remains on. However in the event of lengthy deactivation, the onboard supply control unit -J519- switches off the indicator lamp.
t  Checking operation of heated rear window actuation is described in the guided fault-finding for the onboard supply control unit -J519- and for the air conditioner → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051.
t  As of Model Year 2010 a start/stop system will be available as an optional extra for this vehicle in conjunction with certain engines. On vehicles with a start/stop system, the heated rear window is deactivated whilst the stop function is active (to protect the battery -A-). The setting for actuation of the heated rear window -Z1- does however remain stored. Once the engine has been re-started via the start function, the heated rear window is actuated again → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051.
  Note
t  Operation and actuation of the heated rear window are displayed in the measured value block of the air conditioning system control unit -J301- → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051.
t  The heated rear window -Z1- is switched off automatically at ambient temperatures above 0 °C on completion of the operating time stored in the onboard supply control unit -J519- (approx. 10 minutes) by -J519-.
t  At ambient temperatures below 0 °C, the heated rear window remains switched on until the ignition is switched off (manual deactivation and re-activation are possible at any time). If the temperature rises above 0 °C during a driving cycle, the heated rear window is switched off on completion of the operating time (approx. 10 minutes) stored in the onboard supply control unit -J519-.
  A87-10275

Checking actuation of seat heating (optional extra) > < Vehicles with automatically controlled air conditioner