Checking heated rear window Z1, vehicles with manually controlled air conditioner (heater without air conditioner) — AUDI

Checking
heated rear window
Z1
, vehicles with manually controlled air conditioner (heater without air conditioner)
Procedure
The heated rear window is switched on via button
2
on the operating unit (
air conditioning system control unit
J301
/
heater control unit
J65
).
Note
When button
2
is pressed with the ignition switched on, the
onboard supply control unit
J519
is activated by the operating unit (
air conditioning system control unit
J301
/
heater control unit
J65
) via the data bus. As soon as
J519
switches the rear window heating on (only with engine running), the indicator lamp in button
2
lights up (
J519
sends feedback signal via data bus). The heated rear window is switched off by pressing the button again and switching off the ignition
Owner's Manual
and
Current flow diagrams, Electrical fault finding and Fitting locations
.
If the voltage measured at
J519
at terminal
“30”
drops below a value stored in
J519
or the operating unit (
J301
/
J65
), the rear window heating is deactivated completely (or the power is reduced). The load on the
alternator
C
is then reduced
Vehicle diagnostic tester
(
“Guided Fault Finding”
).
Z1
is only activated by
J519
when the engine is running. When the engine is stopped, there is no activation and no feedback from
J519
; the LED in button
2
does not light up or goes out again shortly after it is pressed
Owner's Manual
and
Current flow diagrams, Electrical fault finding and Fitting locations
.
If
Z1
has to be shut off due to undervoltage, the indicator lamp in button
2
for rear window heating in the operating unit
J301
(
J65
) stays on. However, should the shut-off last longer,
J519
switches off the indicator lamp.
The
“Read measured values”
function of the Guided Fault Finding routine for the operating unit
J301
(
J65
) indicates that the rear window heating is switched on or why there is no activation although there is a corresponding request
Vehicle diagnostic tester
(
“Guided Fault Finding”
).
The procedure for checking the actuation of the rear window heating is described in
Vehicle diagnostic tester
(
“Guided Fault Finding”
).
Z1
is switched off automatically by
J519
at ambient temperatures above 0 °C after the operating time stored in
J519
(approx. 10 minutes).
At ambient temperatures below 0 °C,
Z1
remains switched on until the ignition is switched off (it can be switched off and on again manually at any time). If the temperature rises above 0 °C while the vehicle is being driven,
Z1
is switched off after the operating time (approx. 10 minutes) stored in
J519
.
On vehicles with a start/stop system, the rear window heating might be deactivated while the stop function is active (to protect the
battery
A
). However, the setting for activation of
Z1
remains stored. The rear window heating is switched on again after the engine has been re-started via the start function
Vehicle diagnostic tester
(
“Guided Fault Finding”
).