With Manufacturer's Scan Tool
Leak Detection Pump (LDP) -V144-, Checking
Special Tools and Equipment
- VAG 1526A
- VAG 1527B
- VAG 1594A
- VAG 1598/31
- VAS 5051
Test requirements
- Ignition switched on.
- VAS 5051 tester connected, vehicle On Board Diagnostic (OBD) and -01 Engine electronics- selected.
Checking activation
Display on VAS 5051:
- In selection -1-, click on the diagnostic function "03 - Output Diagnostic Test Mode (DTM)".
Display on VAS 5051:
A - Actuator test is waiting
Advancing by switching required
1 - Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-
- Press -> button repeatedly, until the following display appears:
Display on VAS 5051:
A - Actuator test is waiting
Advancing by switching required
6 - Leak Detection Pump (LDP) tank ventilation system
- Click on -> button
Display on VAS 5051:
A - Actuator test is running
Advancing by switch is allowed
- Leak detection pump (LDP) -V144- will be activated for approximately 1 minute.
NOTE: The operating noise of the LDP is audible at left rear wheel housing.
- End function "03 - output Diagnostic Test Mode (DTM)" by pressing <- button.
- Select "06 - End Output"
- Switch ignition off.
If Leak Detection Pump (LDP) is not activated (no operating noise audible):
- Remove Leak detection pump (LDP) -V144- and disconnect electrical harness connector.
Checking internal resistance
- Connect multimeter for resistance measurement as follows.
Leak detection pump (LDP) -V144- Terminal Specified value
1 + 3 640 - 720
2 + 3 15 - 17
If specified values are not obtained:
- Replace Leak detection pump (LDP) -V144-.
If specified values are obtained:
- Check voltage supply of LDP.
Checking voltage supply
NOTE: Voltage is supplied to the Leak Detection Pump (LDP) via the Fuel Pump (FP) relay.
Test requirement
- Fuse for Leak Diagnostic Pump (LDP) OK
- Connect V.A.G 1527B voltage tester as follows:
Wiring harness connector terminal Measure to
3 Engine Ground (GND)
- Operate starter briefly.
- LED must light up.
- Check electrical wire connection from terminal 3 to Fuel Pump (FP) relay via fuse for open circuit.
- Repair open circuit if necessary.
Checking output wire
- Connect V.A.G 1527B voltage tester as follows:
Wiring harness connector terminal Measure to
2 B+
- Initiate output Diagnostic Test Mode (DTM) and activate Leak Detection Pump (LDP).
Display on VAS 5051:
If LED does not blink:
A - Actuator test is running
Advancing by switch is allowed
6 - Leak Detection Pump (LDP) tank ventilation system
- LED must blink.
If LED does not blink:
- End function "03 - Output Diagnostic Test Mode (DTM)" by pressing <- button.
- Select "06 - End Output"
- Switch ignition off.
- Connect V.A.G 1598/31 test box to harness connectors of wiring harness (do not connect ECM). Connect Ground (GND) clip of test box (not visible in illustration) to Ground (GND).
CAUTION: To avoid damaging electronic components, set measuring range before connecting test leads and observe all test requirements.
- Check the following wire connection for open circuit and short circuit to Ground (GND) and B+:
Wiring harness connector terminal V.A.G 1598/31 test box socket
2 25
- Repair open circuit or short circuit if necessary.
If no malfunctions are found, but Leak Diagnostic Pump (LDP) does not function during output Diagnostic Test Mode (DTM):
- Replace Leak detection pump (LDP) -V144-.
- Observe safety precautions after re-connecting Engine Control Module (ECM).
Checking input wire
- Switch ignition off.
- Connect V.A.G 1598/31 test box to harness connectors of wiring harness (do not connect ECM). Connect Ground (GND) clip of test box (not visible in illustration) to GND.
CAUTION: To avoid damaging electronic components, set measuring range before connecting test leads and observe all test requirements.
- Check the following wire connection for open circuit and short circuit to Ground (GND) and B+:
Wiring harness connector terminal V.A.G 1598/31 test box Socket
1 80
- Repair open circuit or short circuit if necessary.
- Observe safety precautions after reconnecting Engine Control Module (ECM).