Fuel Pump (FP) Control Module -J538-, Checking

Fuel Pump (FP) Control Module -J538-, Checking

Special tools, testers and auxiliary items

- V.A.G 1526 A
- V.A.G 1594 A
- V.A.G 1598/31
- VAS 5051 with VAS 5051/5a

Test conditions:
- Battery voltage at least 12.7 V

- Safety device S81 OK (card location C) in the relay support driver's side behind the driver's side shelf

- Fuel pump relay on card location 4 in the central electrical connection behind the driver's side shelf
- Switch ignition off

Test sequence
- Remove the right rear airbag.
- Remove foam material block from the cavity under the right rear seat belt fastener.

Voltage supply, checking

- Disconnect connector -4- for Fuel Pump (FP) Control Module -J538- -2-.

- Connect the multimeter for voltage measurement as specified below.

Connector terminal Desired value
2 Engine ground

- Connect VAS 5051 and select "01 - engine electronics". Switch ignition on.

VAS 5051:

- Select diagnostic function -1- "03 - control module diagnosis".

VAS 5051:

A - Output check test waiting

Continue as required

1 - Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-
- Select -> key.
- Desired value: Battery voltage
- Quit "03 - control member diagnosis" by selecting <- key

Desired value not reached:
- Repair wiring concern using circuit diagram
- Connect the multimeter for voltage measurement as specified below.

Connector terminal Desired value
1 Battery pos. (+)

- Desired value: Battery voltage

Desired value not reached:
- Repair wiring concern using circuit diagram
- Re-connect connector

Activation by ECM, checking

- Disconnect connector -3- for Fuel Pump (FP) Control Module -J538- -2-.

NOTE: Connectors -1- and -4- remain connected.

- Connect the multimeter for voltage measurement as specified below.

Connector terminal Desired value
5 Battery pos. (+)

- Briefly operate starter
- Desired value: Briefly (approx. 1 second) approx. battery voltage, then it drops to 10 V

Desired value not reached:

- Connect test box VAG1598/31 to the circuit harness connector; do not connect the ECM. Connect the ground clip of the test box to ground (not shown in illustration).

WARNING: To avoid damaging electrical components, select the appropriate measurement settings on the measuring device before connecting to the components.

- Check following line connection for interruption and short-circuit after mass and/or plus:

Connector terminal Test box V.A.G 1598/22 Socket
5 114

- Repair short circuit and/or circuit malfunction using circuit diagram

Diagnosis circuit, checking

- Check the following circuit connections for open circuits and shorts to ground and/or battery positive (+):

Connector terminal Test box VAG 1598/31 Socket
2 74

- Repair the open circuit and or the short according to the schematics.

Voltage Supply For Fuel Pump (FP) -G6- (of The Fuel Pump (FP) Control Module -J538-), Checking

NOTE: Electrical circuits -1- to the fuel pump can not be disconnected from the control module -2- for the fuel pump. This is why the voltage supply is measured directly at the fuel pump.

- Remove rear seat
- Remove cover located under rear seat
- Briefly operate starter
- Operating noise of the Fuel Pump (FP) -G6- must be audible at the locking flange (right)

NOTE: Fuel pump runs very quietly. During the checking of the fuel pump, excess noise should be avoided.

If no operating noise is audible:

- Connect the multimeter for voltage measurement to contacts 1 and 4 as shown, using probes and adapters from VAG 1594 A; the connection remains disconnected.

NOTE: Pin numbers are located on the back of connector

- Briefly operate the starter
- Desired value: Briefly (approx. 1 second) approx. battery voltage, then it drops to 10 V

Desired value not reached:
- Check the circuit connection between fuel pump control module -J538- and fuel pump -G6- for open circuits according to the schematics.

No problem found:
- Replace Fuel Pump (FP) Control Module -J538-.

Voltage Supply For Fuel Pump -G23 (from Fuel Pump Control Module -J538), Checking

- Remove screw -3- and pull fuel pump downward; Fuel hoses -2- and - 4- and connector -1- remain connected.

- Connect the multimeter for voltage measurement to contacts 1 and 2 as shown, using probes and adapters from VAG 1594 A; the connection remains disconnected.
- Briefly operate starter
- Desired value: Voltage briefly climbs to approx. 12 V, then falls to approx. 10 V

Desired value not reached:
- Check wiring between Fuel Pump (FP) Control Module -J538- and Transfer Fuel Pump (FP) -G23- using circuit diagram

If no error is found:
- Replace Fuel Pump (FP) Control Module -J538-.

Tightening torque

Component Nm
Retaining clip for fuel pump 1.2 Nm (10.6 in. lb)