AUDI A4 1998 B5 / 1.G Rear Window Heating Electrical Testing Workshop Manual

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Rear window heating,
electrical testing

Note:
Only perform this test on A/C control heads -E87-
with only one display (switch for rear window
heating is integrated in the A/C control head -
E87-).

Special tools and equipment

VAG1715 multimeter (with voltage probe)
VAG1594A Measuring Appliance Adapter

Test requirements
All fuses OK

Electrical Wiring Diagrams, Troubleshooting &
Component Locations binder

- Switch ignition off.

- Remove A/C control head -E87- page 87
-
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- Disconnect harness connector E from A/C
control head -E87-.

- Connect multimeter between terminal 1 and 2 for voltage
measurement.
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- Turn ignition on.

Specification: approx. battery voltage

- Switch ignition off.

- Connect harness connector E at A/C control
head -E87-.

Note:
All harness connectors at A/C control head -E87- must be connected. - Route wire -A- to harness connector E through current probe on
VAG1715.
- Select "Amperage measurement via amperage probe" function on
VAG1715 (with voltage probe).
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- Start engine.

- Switch rear window heating on via A/C control
head -E87- (indicator lamp in button lights up).

Specified value: The display on VAG1715 will
change from approx. 0 amps to less than 25
amps.

- Wait approx. 10 minutes.

Specified value: The display on the VAG1715
will change from less than 25 amps to approx. 0
amps (indicator lamp in button goes out).

Notes:

The current probe may be influenced by stray
current which could cause the display to show a
low current reading when rear window heating
is switched off.
The A/C control head -E87- will switch rear
window heating off after 10 minutes.
When the outside temperature is less than 0 C
the heating function of the rear window will
remain on until the ignition is switched off (it can
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be turned off manually at any time). If the
temperature while driving exceeds 0 C, the
rear window heater is turned off after the
operating time stored in -E87- (max. 10
minutes) elapses.
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