Activating leak detection pump (LDP) V144 :

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Press → key.

Indicated on display:

Output Diagnostic Test Mode (DTM) →
Leak Detection Pump (LDP) Tank vent. system

Leak detection pump must start up in intervals.

If leak detection pump does not start running:

Fig 1: Locating 3-Pin Connector At Fuel System Leak Detection Pump V144

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Disconnect 3-pin connector from Leak Detection Pump (LDP) V144.
Pull connector off solenoid valve - 1 - and connect voltage tester VAG1527B with auxiliary cables from VAG1594 to disconnected connector contacts 2 + 3.

LED must flash

LED flashes:

Proceed with Output Diagnostic Test Mode until completed.
Switch ignition off.
Replace Leak Detection Pump (LDP) V144. → 20 - FUEL SUPPLY
Check DTC Memory, if necessary, repair any malfunctions and then Erase DTC Memory → DTC memory (functions 02 and 05), checking and erasing

Read readiness code → Readiness code, reading . If DTC memory has been erased, readiness code must be generated again:

Engine code AWW, → Readiness code for engine code AWW, generating

Engine code AWP, → Readiness code for engine code AWP, generating

LED does not flash:

Proceed with Output Diagnostic Test Mode until completed.
Switch ignition off.

Fig 2: Identifying Test Box V.A.G 1598/31 Connected To Control Module Wiring Harness

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Connect test box VAG1598/31 to control module wiring harness. Engine control module remains disconnected.
Check wire between test box socket 80+3 pin connector contact 2 for open circuit using wiring diagram.

Wire resistance: max. 1.5 Ω

Check wire between test box socket 25+3 pin connector contact 2 for open circuit using wiring diagram.

Wire resistance: max. 1.5 Ω

Additionally check wire for short to battery positive and Ground (GND).

If no malfunction in wire is detected:

Check wire between 3 pin connector contact 3 and fuel pump (FP) relay J17 for open circuit using wiring diagram.

Wire resistance: max. 1.5 Ω

If no wiring malfunction is detected:

Replace engine control module → Engine control module, replacing .