1997 AUDI A4 EVAP Workshop Manual

20-150
If you measure values other than specified
values:

- Replace Leak Detection Pump (LDP) -V144
Page 20
-162
.
If you reached specified values:

- Check voltage supply to electrical connector of
LDP Page 20
-151
.
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20-151

Checking voltage supply (all vehicles)

Note:
Voltage supply to the LDP is via the fuel pump
relay.

Test condition:

Fuse for LDP is OK

- Disconnect connector from LDP.

- Connect voltage tester VAG1527 B as follows:Connector terminal
Measure
3 Engine Ground (GND)
- Briefly operate starter motor.
LED must light up.
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20-152
If LED does not light up:

Electrical Wiring Diagrams, Troubleshooting & Component Locations
If wiring is OK:
Repair Manual, Fuel Injection & Ignition, Repair Group 24 - Check electrical wiring from terminal 3 via fuse for fuel pump relay for
open circuit. - Repair wiring as necessary.
- Check fuel pump relay:
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20-153

Checking output wiring (vehicles with
mechanical throttle activator)

- Remove weatherstrip at plenum chamber -arrows-.
- Remove cover for plenum chamber -1- toward front.
- Remove cover for E-box in plenum chamber.

Note:
Disconnect or connect the Engine Control Module (ECM) connector only
with ignition switched off. - Carefully lever off clamp -arrow- with screwdriver.
- Unlatch clip and disconnect connector for Engine Control Module
(ECM).
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20-154


- Connect test box VAG1598/22 to harness connector. Do not connect
ECM.

- Check the following wire connection for open circuit and short circuit to
Ground (GND) or to plus (B+): Electrical connector terminal
Test box VAG1598/22 socket
2 16
- Repair wiring or short circuit as necessary.
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20-155
If you did not find any malfunction, however the
Leak Detection Pump (LDP) did not function
during the output Diagnostic Test Mode (DTM):

- Replace Leak Detection Pump (LDP) -V144
Page 20
-162
.
If the LED does not blink, although wiring is OK:

- Replace Engine Control Module (ECM):

Repair Manual, Fuel Injection & Ignition,
Repair Group 24
- Generate readiness code:

Repair Manual, Fuel Injection & Ignition,
Repair Group 24
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20-156

Checking output wiring (vehicles with
electronic throttle control)

- Connect voltage tester VAG1527B as follows:Electrical connector terminal
Specification
2 Battery Positive
- Initiate Diagnostic Test Mode (DTM) Page 20
-146
.
-
Press button until following display is shown:
Output Diagnostic Test Mode LDP leak test

Indicated on display:
If LED does not blink:
LED must blink
- Switch ignition off.
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20-157


- Remove weatherstrip at plenum chamber -arrows-.
- Remove cover for plenum chamber -1- toward front.
- Remove cover for E-box in plenum chamber.

Note:
Disconnect or connect the Engine Control Module (ECM) connector only
with ignition switched off. - Carefully lever off clamp -arrow- with screwdriver.
- Unlatch clip and disconnect connector for Engine Control Module
(ECM).
Pa
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ystem, servicin
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11/18/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE04.20.5