Leak Detection Pump, Checking

Observe all safety precautions: SAFETY PRECAUTIONS 

View clean working conditions: CLEAN WORKING CONDITIONS 

Use only gold-plated terminals when servicing any component with gold-plated electrical harness connector terminals.

For wiring diagrams, component locations, and connector views, Refer to the applicable wiring diagram.

Special tools and workshop equipment required 

• multimeter
• Wiring diagram.

Test requirements 

• The Leak Detection Pump (LDP) -V144- fuse OK.
• The ignition switched off.

Test procedure 

-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK 

Start diagnosis 

-- Remove the left rear wheel housing liner. Refer to appropriate service information.

-- Disconnect the Leak Detection Pump (LDP) -V144- electrical harness connector -2-.

Checking internal resistance 

-- Using a multimeter, check the Leak Detection Pump (LDP) -V144- for resistance as follows:

Leak Detection Pump (LDP) -V144- electrical harness connector terminals	Specified values
1 + 3	640 to 720 Ω
2 + 3	15 to 17 Ω

If any of the specifications are not obtained:

-- Replace the Leak Detection Pump (LDP) --V144--. Refer to appropriate service information.

If the specified values are obtained:

Checking voltage supply 

-- Check the Leak Detection Pump (LDP) --V144-- for voltage.

-- Using a multimeter, check the Leak Detection Pump (LDP) --V144-- electrical harness connector terminal 3 for voltage.

Leak Detection Pump (LDP) --V144-- electrical harness connector terminal	Measure to
3	Engine Ground (GND)

-- Operate the starter briefly.

Specified value: battery voltage.

-- Switch the ignition off.

If the specified value was not obtained:

-- Using a multimeter, check the Leak Detection Pump (LDP) --V144-- electrical harness connector terminal 3 to the Motronic Engine Control Module (ECM) Power Supply Relay -J271- terminal 2/87 for an open circuit.

Specified value: Wire resistance max 1.5 Ω.

If the specification is not obtained:

-- Check the wiring for a short circuit to Battery positive (+) or an open circuit.

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

-- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring and if the voltage supply was OK:

Checking wiring 

If the manufacturers test box is being used, perform the following step.

-- Install the test box.

If the manufacturers test box is not being used, perform the following step.

-- Remove the Motronic Engine Control Module (ECM) -J623-. Refer to appropriate service information.

-- Using a multimeter, check the Leak Detection Pump (LDP) --V144-- electrical connector terminal 1 to Motronic Engine Control Module (ECM) -J623- electrical connector T94 terminal 44 for an open circuit.

-- Using a multimeter, check the Leak Detection Pump (LDP) --V144-- electrical connector terminal 2 to Motronic Engine Control Module (ECM) -J623- electrical connector T94 terminal 49 for an open circuit.

Leak Detection Pump (LDP) --V144-- electrical harness connector terminals	Motronic Engine Control Module (ECM) -J623- electrical connector T94 terminals or test box socket
1	44
2	49

Specified value: 1.5 Ω max.

If the specification is not obtained:

-- Check the wiring for a short circuit to Battery positive (+) or an open circuit.

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

-- If necessary, repair the faulty wiring connection.

If no malfunction is found in wiring:

-- Replace the Motronic Engine Control Module (ECM) -J623-. Refer to appropriate service information.

Assembly is performed in the reverse order of the removal, note the following:

-- Install the left rear wheel housing liner. Refer to appropriate service information.

Final procedures 

After the repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
2. If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
3. If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .