Rear Window Defogger, Checking; Wiring And Component Testing With Test Box Vag 1598A - Audi TT Repair Manual

4.11

Rear Window Defogger, Checking

Note
There is a condition, which will not let the rear window de‐
♦
froster switch on. Short circuit in the rear window connector,
open circuit in the voltage supply to the Climatronic control
module -J255- etc.. If this is stored as a fault in the Climatronic
control module, refer to -VAS5051B- under "Guided Fault
Finding".
If voltage measured at the Vehicle Electrical System Control
♦
Module -J519- at terminal 30 falls below a value stored in the
control module, then the rear window heater will be completely
switched off (or output is decreased), and thus the load on
Generator is relieved (activation duty cycle of 100% reduced
to 90% by the Climatronic control module). Refer to -
VAS5051B- under "Guided Fault Finding".
If heated rear window must be switched off due to insufficient
♦
voltage, indicator lamp in heated rear window button on Cli‐
matronic 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.
Climatronic control module measured value block indicates
♦
that heater of Heated Rear Window is switched on or why no
activation is occurring despite a request. Check using -
VAS5051B- under "Guided Fault Finding".
The function test for the heated rear window is described in
♦
Guided Fault Finding, vehicle electrical system control module
-J519- . Refer to -VAS5051B- under "Guided Fault Finding".
(Vehicle electrical system control module controls the heated
rear window -Z1- ).
The heated rear window stays switched on at outside temper‐
♦
atures up to 0°C until ignition is switched off (heated rear
window can be switched manually at anytime). If temperature
becomes greater than 0 °C during a driving period, the heated
rear window is switched off after operating time stored in Cli‐
matronic control module has elapsed (approximately 10 mi‐
nutes).
Heated rear window may be switched off automatically by the
♦
Climatronic control module at outside temperatures greater
than 0 °C after the operating time (approximately 10 minutes)
stored in control head has elapsed (time of activation depends
on coding and version of control head). Check using -
VAS5051B- under "Guided Fault Finding".
4.12 Wiring and Component Testing with
Test Box VAG 1598A
Special Tools and Equipment
♦ Test Box (Basic Unit -V.A.G 1598/14- with Adapter -V.A.G
1598/11- and Adapter - 16 Terminals -V.A.G 1598/12-
♦ Vehicle diagnosis, testing and information system -
VAS5051B- with multimeter leads -VAS 5051/7- , DSO meas‐
uring leads 1 & 2 -VAS 5051/8- and inductive pickup (50 amp)
-VAS 5051/9-
♦ Voltage Tester -V.A.G 1527 B-
♦ Connector Test Set -V.A.G 1594 C-
♦ Temperature measuring device, for example, a commercially
available thermometer.
Heating, Ventilation and Air Conditioning - Edition 01.2011
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with respect to the correctness of information in this document. Copyright by AUDI AG.
Audi TT 2007 ➤
101
4. Diagnosis and Testing