Leak Detection Pump, Checking

Special tools and workshop equipment required

Multimeter VAG1526 or multimeter VAG1715
Connector test kit VAG1594
Wiring diagram

Test requirements

Fuses in E-box (in plenum chamber, left) must be OK: Refer to SYSTEM WIRING DIAGRAM

Fig 1: Identifying Fuses In E-Box (In Plenum Chamber, Left)
Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.
Motronic Engine Control Module (ECM) Power Supply Relay -J271- must be OK, check: Refer to SYSTEM WIRING DIAGRAM
Ground (GND) connections between engine and chassis must be OK.
Ignition switched off.

Test sequence

-- Remove rear right wheelhousing liner.

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

Fig 2: Disconnecting 2-Pin Connector From Evaporative Emission (EVAP) Canister Purge Solenoid Valve -N115-

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

Checking resistances

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

Fig 3: Identifying Leak Detection Pump (LDP) V144 Electrical Harness Connector Terminals

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

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.

Checking wiring

-- Connect test box to control module wiring harness, connect test box for wiring test.

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

Fig 4: 3-Pin Electrical Harness Connector & Terminals

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

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 .