Leak Detection Pump (LDP) V144, Checking - Up to 10.04
Leak Detection Pump (LDP) V144, Checking (Vehicles With MPI-Engine)
Special tools, testers and auxiliary items required
- Hand multimeter V.A.G 1526 A or V.A.G 1526 B
- Voltage tester V.A.G 1527 B
- Connector test kit V.A.G 1594 A or V.A.G 1594 C
- Test box V.A.G 1598/31
- Vehicle Diagnostic, Testing and Information System VAS 5051 A with diagnostic cable VAS 5051/5 A
Test conditions
- Ignition switched on.
- Vehicle Diagnostic, Testing and Information System VAS 5051 A connected, On-board diagnostics and vehicle system "01 Engine electronics" selected.
Check activation
Display on VAS 5051 A:
- In selection - 1 -, click on diagnostic function "03. Output Diagnostic Test Mode (DTM)".
Display on VAS 5051 A:
A. Output diagnostic test mode waiting, Advancing by switching required
1. Evaporative Emission (EVAP) Canister Purge Regulator Valve N80
- Press -> button repeatedly until leak detection pump for fuel system is activated
NOTE: Operating noise of Leak Detection Pump (LDP) is audible at left rear wheelhousing.
- End function "03. output Diagnostic Test Mode (DTM)" by pressing button.
- From selection, click on diagnostic function "06. End output".
- Switch off ignition.
If Leak Detection Pump (LDP) for fuel system is not activated (no operating noise audible):
- Remove leak detection pump (LDP) V144 and disconnect the electrical connection.
Checking internal resistance
- Connect hand multimeter V.A.G 1526 A or V.A.G 1526 B for resistance measurement as follows.
Leak detection pump Specified value
(LDP) Terminal
- 1 + - 3 - 640 to 720 ohm
- 2 + - 3 - 15 to 17 Ohms
If specifications are not obtained:
- Replace Leak Detection Pump (LDP) V144
If specified values are achieved:
- Check voltage supply of leak detection pump.
Checking voltage supply
NOTE: Voltage is supplied to the leak detection pump via the Fuel Pump (FP) relay J17.
Test conditions
- Fuse for leak detection pump OK
- Connect voltage tester V.A.G 1527 B as follows:
Harness connector Terminal Measure to
- 3 - Engine Ground (GND)
- Briefly operate starter.
- LED must light up.
If LED does not light up:
- Check electrical harness connection from terminal - 3 - via fuse to Fuel Pump (FP) Relay J17 for open circuit according to wiring diagram.
- Repair open circuit in wiring according to wiring diagram.
Checking output wire
- Connect voltage tester V.A.G 1527 B as follows:
Harness connector Terminal Measure to
- 2 - Battery positive (B+)
- initiate output Diagnostic Test Mode (DTM)
Display on VAS 5051 A:
A. Output diagnostic test mode waiting, Advancing by switching required
1. Evaporative Emission (EVAP) Canister Purge Regulator Valve N80
- Press -> button repeatedly until leak detection pump for fuel system is activated
- LED must blink.
If LED does not blink:
- End function "03. output Diagnostic Test Mode (DTM)" by pressing button.
- From selection, click on the diagnostic function "06. End output".
- Switch off ignition.
- Connect test box V.A.G 1598/31 to wiring harness connectors, with Engine Control Module (ECM) not connected. Connect Ground (GND) clip at test box to Ground (GND) (not visible in illustration). Test Box, Connecting For Wiring and Component Test
CAUTION: To avoid damaging electronic components, switch to the corresponding measuring range and observe all test conditions before connecting the test leads.
- Check the following wire connection for open circuit and short circuit to Ground (GND) and B+:
Harness connector Terminal Test box V.A.G 1598/31Socket
- 2 - 25
- Repair wiring open circuit or short circuit according to wiring diagram.
If no malfunction is found, but leak diagnosis pump is not functional during output diagnostic test mode:
- Replace Leak Detection Pump (LDP) V144
- Observe procedures for after re-connecting engine control module (ECM).
Checking input wiring
- Switch off ignition.
- Connect test box V.A.G 1598/31 to wiring harness connectors, with Engine Control Module (ECM) not connected. Connect Ground (GND) clip at test box to Ground (GND) (not visible in illustration). Test Box, Connecting For Wiring and Component Test
CAUTION: To avoid damaging electronic components, switch to the corresponding measuring range and observe all test conditions before connecting the test leads.
- Check the following wire connection for open circuit and short circuit to Ground (GND) and B+:
Harness connector Test box V.A.G 1598/31Socket
Terminal
- 1 - 80
- Repair wiring open circuit or short circuit according to wiring diagram.
- Observe procedures for after re-connecting engine control module (ECM).