1997 AUDI A4 AC System On Board Diagnostic Workshop Manual

01-42

Output Diagnostic Test Mode (DTM)
(function 03)


Function
Output DTM allows functional checking of A/C
control head actuated components (DTM
components). Actuators receive output signals
generated by the control head via VAG1551
Scan Tool (ST) in sequence. Function is
confirmed in accordance with specified
responses.
The following components are tested in
sequence using Output DTM:

1 - A/C Clutch -N25-

2 - Fresh Air Blower -V2-

3 - Coolant Fan -V7-

4 - Fresh Air/Recirculating Flap Two-Way Valve
-N63-1)

5 - Temperature Regulator Flap Motor -V68-

6 - Central Air Flap Motor -V70-
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7 - Footwell/Defroster Flap Motor -V85-

8 - Air Flow Flap Motor -V71-

9 - Interior Temperature Sensor Fan -V42-

10 - A/C control head display segment test

11 - Outside Air Temperature Display -G106-
test

1) Not installed on m.y. 1997 vehicles.
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01-43
Notes:

During Output DTM on vehicles with Control Head (E87) Part Number 8D0 820 043 D, A/C Compressor Clutch (N25) DTC
"01270, mechanical malfunction SP" may be stored even though no malfunction is present. Corrective action: When
output DTM is complete, check DTC memory. If above DTC is present, erase DTC memory.
When starting Output DTM, temperature and air distribution flap flap motors move to pre-determined positions in
preparation for individual tests: Temperature Regulator Flap Motor V68: moves to "heat" position. Central Air Flap Motor -
V70- moves to "floor & defroster outlet" position. Footwell Defroster Flap Motor V85 moves to "defrost" position.
Output DTM can be repeated several times, if necessary.
During Output DTM, vehicle must not be moved and engine speed must be less than 3000 rpm.
During Output DTM, A/C system control is switched off and all segments in both A/C control head displays are actuated.
Interior temperature sensor fan -V42- is activated via an A/C control head:
with one display after activation of the coolant fan.
with two displays after activation of air flow flap motor.
Outside air temperature display -G106- is activated via an A/C control head
with one display after activation of air flow flap motor.
with two displays after activation of idle regulation.
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For the A/C control head -E87-, the instrument panel interior temperature sensor -G56- is installed with only one display in
the -E87-. -V42- and -G56- are not individually replaceable. If -E87- is malfunctioning, they must be replaced together.
A/C control heads with one display indicate that output diagnostic test mode is completed after activation of the last
component ("END" is indicated on the Scan Tool display).
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01-44

Starting output Diagnostic Test Mode (DTM)

- Start engine, switch on compressor (press
"Auto" button), adjust air flow to center
instrument panel outlets only.

- Connect Scan Tool VAG1551 or 1552 in
operating mode -1-, enter address word 08 "A/C
Heating Electronics" and move forward in
program until "select function XX" appears in the
display.

- Switch on printer by pressing the PRINT button
(indicator lamp in button comes on).

- Check DTC memory page 01
-18
.

- Note any stored DTCs for reference and move
forward in program until "select function XX"
appears in the display. Rapid data transfer
HELP
Select function XX

Indicated on display (function selection)
- Press buttons -0- and -3-.
Rapid data transfer
Q
03 - Output Dia
gnostic Test Mode

Indicated on display
- Press -Q- button to confirm input.
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Output Dia
gnostic Test Mode
A/C Clutch - N25

Indicated on display
-
Advance through all DTM component checks using button.- Refer to output DTM table page 01
-46
to confirm function of DTM
components and test results.
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01-45

Notes:

If a DTM component fails to respond as
specified, perform all corrective actions, checks
and tests recommended in output DTM table
page 01
-46
.

A/C system component locations: engine
compartment page 87
-96
(note specific
model year information).

A/C system component locations: passenger
compartment page 87
-106
(note specific
model year information).

Output DTM can be ended by pressing the -C-
button.
After ending output DTM, check DTC memory
page 01
-18
.

If the readout "function unknown or cannot be
carried out at the moment" appears in the
display at the start of output DTM, e.g. when
engine not running, press button and once
again select "function 03 Output Diagnosis Test
Mode (DTM)" (DTM component "A/C Clutch
N25" is no longer actuated for this test).
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If the readout "function unknown or cannot be
carried out at the moment" appears in the
display page 01
-63
, Read measuring value
block (display group 1).
Function is unknown or cannot be carried out at the moment!

Indicated on display
- If this readout appears in the display, output Diagnostic Test Mode
(DTM) is ended.
- VAG1551 Scan Tool (ST) can be returned to the function mode by
pressing the button.
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