Leak Detection Pump, Checking

Special tools and workshop equipment required 

• Multimeter VAG 1526 or Multimeter VAG 1715
• Connector test kit VAG 1594
• Wiring diagram

Test Prerequisites 

• Fuses in E-box (plenum chamber, left) must be OK: Refer to appropriate SYSTEMS WIRING DIAGRAM
  Fig 1: Identifying Fuses In E-Box (Plenum Chamber, Left)

  Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.
• Motronic Engine Control Module (ECM) Power Supply Relay -J271- must be OK, check: appropriate SYSTEMS WIRING DIAGRAM
• Ground (GND) connections between engine and chassis must be OK.
• Ignition switched off.

Test Sequence 

-- Remove rear right wheel housing liner.

-- Disconnect 3-pin connector of Leak detection pump (LDP) -V144- (-2-).

Checking Resistance

-- Measure resistance between terminals 1 + 3 of diagnostic pump.

Specified value: 640 to 720 Ω

-- Measure resistance between terminals 2 + 3 of diagnostic pump.

Specified value: 12.0 to 20.0 Ω

If specified values are not obtained:

-- Replace Leak Detection Pump (LDP) -V144-

-- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data.

-- Generate readiness code.

If specified values are obtained:

-- Check wires according to wiring diagram.

Wiring, Checking 

-- Connect test box.

-- Check wires between test box and 3-pin connector for open circuits according to wiring diagram.

Terminal 1+socket 80

Terminal 2+socket 25

Wire resistance: max. 1.5 Ω

-- Also check wires for short circuit to each other, to vehicle Ground (GND) and to B+.

Specified value: ∞ Ω

-- Check wire between 3-pin connector terminal 3 and Motronic Engine Control Module (ECM) Power Supply Relay -J271- for open circuit according to wiring diagram.

Wire resistance: max. 1.5 Ω

-- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data.

-- Generate readiness code.

If no malfunctions are found in wires:

-- Replace Motronic Engine Control Module (ECM) -J220- ENGINE CONTROL MODULE, REPLACING .

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 .