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 SYSTEM 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 

-- Obtain access to the Evaporative Canister under the luggage compartment. Refer to appropriate service information.

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

Fig 1: Disconnecting Leak Detection Pump (LDP) V144 Electrical Harness Connector

Courtesy of AUDI OF AMERICA, LLC

Checking internal resistance

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

Fig 2: Checking Leak Detection Pump (LDP) V144 For Resistance

Courtesy of AUDI OF AMERICA, LLC

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.

-- 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 Engine Component Power Supply Relay -J757- terminal 4 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 terminals to Motronic Engine Control Module (ECM) -J623- electrical connector T94 terminal for an open circuit.

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 .