Leak Detection Pump: Testing and Inspection
Special tools and equipment
- VAG1526A
- VAG1527B
- VAG1594A
- VAG1598/31
- VAS5051 with VAG5051/1
or
- VAG1551 with VAG1551/3A
- Initiate output Diagnostic Test Mode (DTM) as follows:
- Connect VAS5051 tester to vehicle with VAS5051/1 diagnostic wire. Alternately, VAG1551 scan tool can also be attached using VAG1551/3A adapter.
NOTE: The following description only explains implementation of On Board Diagnostic (OBD) using the VAG1551 scan tool. When using the VAS5051 tester observe the tester's instructions for use.
Indicated on display 1)
V.A.G - ON BOARD DIAGNOSTIC HELP
1 - Rapid data transfer
2 - Blink code output
1) Operating modes 1 and 2 are displayed alternately
- Switch ignition on.
- Press button 1 to select "Rapid data transfer" operating mode 1.
Indicated on display
Rapid data transfer HELP
Insert address word XX
- Press buttons -0- and -1- to select "Engine Electronics" and press -Q- button to confirm input.
- Press -> button.
Indicated on display
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -3- to select "Output Diagnostic Test Mode" and press -Q- button to confirm input.
Indicated on display
Rapid data transfer Q
03 - Output Diagnostic Test Mode
- Press -Q- button to confirm input.
Indicated on display
Output Diagnostic Test Mode ->
EVAP Canister Purge Regulator Valve -N80
- Press -> button.
Indicated on display
Output Diagnostic Test Mode ->
Leak detection pump tank vent system
Leak Detection Pump (LDP) -V144- will be activated for approximately 1 minute.
NOTE: Operating noise of Leak Detection Pump (LDP) is audible at front right wheelhousing.
If Leak Detection Pump (LDP) is not activated (no audible operating noise):
- Switch ignition off.
- Remove Leak Detection Pump (LDP) -V144-, and disconnect harness connectors. Service and Repair
Checking internal resistance
- Connect multimeter for resistance measurement as follows.
Leak Detective Pump (LDP) Specified value
-V144- terminals
1+3 640 - 720 Ohms
2+3 15 - 17 Ohms
If specified values are not obtained:
- Replace Leak Detection Pump (LDP) -V144-. Service and Repair
If specified values are obtained:
- Check voltage supply at harness connector of Leak Detection Pump (LDP).
Checking voltage supply
NOTE: Voltage supply for the Leak Detection Pump (LDP) runs via the Fuel Pump (FP) relay.
Test requirement
- Fuse for Leak Detection Pump (LDP) OK
- Disconnect connector at Leak Detection Pump (LDP).
- Connect VAG1527B voltage tester as follows:
Electrical harness connector Measure to
terminal
3 Engine Ground (GND)
- Operate starter briefly.
- LED must light.
If LED does not light:
- Check electrical wire connection from terminal 3 via fuse to Fuel Pump (FP) relay for open circuit.
- Repair open circuit if necessary.
If wire connection is OK:
- Check Fuel Pump (FP) relay.
Checking output wire
- Connect VAG1527B voltage tester as follows:
Electrical harness connector Measure to
terminal
2 B+
- Initiate output Diagnostic Test Mode.
- Press -> button until the following is indicated.
Indicated on display (LED must blink).
Output Diagnostic Test Mode ->
Leak detection pump Tank vent syst.
If LED does not blink:
- Switch ignition off.
- Remove windshield wiper arms (unscrew).
- Disconnect cover for plenum chamber and place it on windshield side.
- Disengage locking lugs and remove control module connector.
- Connect VAG1598/31 test box to connector of wiring harness. Ground (GND) clip (arrow) at test box must be clipped to the battery negative terminal. Engine Control Module (ECM) must not be attached.
- Check the following wire connection for open circuit and short circuit to Ground (GND) and B+:
Electrical harness connector VAG1598/31 test box Bushing
terminal
2 25
- Repair open circuit or short circuit if necessary.
If no malfunctions are found, but Leak Detection Pump (LDP) does not function during output Diagnostic Test Mode (DTM):
- Replace Leak Detection Pump (LDP) -V144-. Service and Repair
If LED does not blink, but wire connections are OK:
- Replace Engine Control Module (ECM).
After completing work:
- Generate readiness code.
Checking input wire
- Switch ignition off.
- Connect VAG1598/31 test box to connector of wiring harness.
- Check the following wire connection for open circuit and short circuit to Ground (GND) and B+:
Electrical harness connector VAG1598/31 test box Bushing
terminal
1 80
- Repair open circuit or short circuit if necessary.
After completing work:
- Generate readiness code.