AUDI A4 1999 B5 / 1.G EVAP Owner's Manual

20-146

Checking LDP via output DTM (vehicles with
electronic throttle control)

Note:
In the following description the performance of the On Board Diagnostic
(OBD) procedure the VAG1551 Scan Tool (ST) is used. When using
Vehicle Diagnostics Test and Information System VAS5051, use the
operating instructions. - Connect VAS5051 with diagnostic cable VAS5051/1 or VAG1551 Scan
Tool (ST) with adapter cable VAG1551/3B.
On Board Dia
gnostic
HELP
1 - Rapid data transfer 1
)
2 - Blink code 1)

Indicated on display: 1) Appears alternately
- Switch ignition on.
- Press button 1 to select "Rapid data transfer".
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20-147

Rapid data transfer
HELP
Enter address word XX

Indicated on display:
- Enter "01" for address word "Engine electronics" and confirm input by
pressing Q button.
-
Press button.
Rapid data transfer
HELP
Select function XX

Indicated on display:
- Enter "03" for function "Output Diagnostic Test Mode (DTM)."
Rapid data transfer
Q
03-Output Diagnostic Test Mode

Indicated on display:
- Confirm input by pressing Q-button.
Output Diagnostic Test Mode EVAP Purge Regulator Valve
-N80

Indicated on display (EVAP canister purge regulator valve -N80)
-
Press button until following display is shown:
Output Diagnostic Test Mode Leak Detection Pump

Indicated on display:
Note:
You can hear the leak detection pump run at the left rear wheel housing
when it is working. This will be difficult to hear. Make sure to be as close
to LDP as possible and to eliminate as much surrounding noise as
possible. The leak detection pump is activated for about 1 minute.
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20-148
If LDP -V144 is not activated (pump is silent):

- Switch ignition off.

- Remove LDP ( Page 20
-162
) and disconnect
electrical connector.
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20-149

Checking resistance (all vehicles)

Vehicles manufactured approx. 05.97
Vehicles manufactured approx. 05.97 - Switch multimeter Fluke 83 to resistance and connect as follows:Leak detection pump terminal
Specified value
1 + 3
640 to 720
2 + 3
17.5 to 27.5
Leak detection pump terminal
Specified value
1 + 3
640 to 720
2 + 3
15 to 17
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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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