Fuel Pump Relay: Testing and Inspection

Fuel Pump (FP) Relay -J17 and relay activation, checking

The fuel pump and some of the injection system components are powered via the fuel pump relay -J17.

The Fuel Pump (FP) Relay -J17 will only be activated if the engine is turning over. That means, the relay is only grounded (via the engine control module) when the engine control module is receiving engine speed impulses.

Test conditions
- Battery voltage OK.

Functional test of fuel pump relay


NOTE: The -J17- fuel pump (FP) relay is located in relay socket 4 of the micro central electric panel located under the instrument panel.







- Connect Vehicle Diagnostic, Testing and Information System VAS5051 or VAG 1551 Scan Tool and select engine electronics control module by entering address word "01", Refer to "Scan Tool Testing/Scan Tool Connecting and Initials Checks/Connecting VAG 1551/ VAS 5051 Scan Tool" Testing and Inspection. When doing this the ignition must be switched on.

- Start output Diagnostic Test Mode (DTM), Refer to "Scan Tool Testing/Output Diagnostic Test Mode (DTM) (Function 03)" Testing and Inspection. The fuel pump must be running.







The fuel pump relay should activate and the fuel pump should run.

If the relay does not activate:
- Check activation of fuel pump relay.

If fuel pump does not run:
- Check activation of fuel pump and other components.

Checking activation of fuel pump relay

- Switch ignition off.
- Connect VAG 1598/31 test box to wiring harness for engine control unit. DO NOT connect to engine control module itself, Refer to "Scan Tool Testing/Scan Tool Connecting and Initials Checks/Connecting VAG 1598/31 Test Box" Testing and Inspection
- Connect sockets 65 and 2 of test box to each other using test leads from VAG 1594 connector test kit.
Specification: The fuel pump relay (relay position 4) should be activated

If the relay is now activated but not during the output Diagnostic Test Mode (DTM):
- Replace Engine Control Module (ECM).

If the relay does not activate:







- Disconnect fuel pump relay from relay panel (relay position 4).







Connect multimeter (voltage measurement range) between Ground (GND) and terminal 19 on relay panel.
Specification: approx. battery voltage

If the specification is not obtained:
- Check wiring.

If the specification is obtained:







- Test for open circuit and short to B+ or Ground (GND) in the following wiring connection:

Micro central electrics in VAG 1598131 test box
passenger's foot well (right), socket
relay position 4
terminal
16 65

- Correct any open/short circuit as necessary.

If no malfunction is detected in the wire:
- Replace Fuel Pump (FP) Relay -J17.
- Display readiness code, Refer to "Monitors, Trips and/or Drive Cycle (Readiness Codes)/Displaying Readiness Code" Testing and Inspection. Readiness code must be generated if DTC memory was erased, Refer to "Monitors, Trips and/or Drive Cycle (Readiness Codes)/Generating Readiness Code" Testing and Inspection

Checking activation for fuel pump and components







- Remove fuse 28.
- Start Output Diagnostic Test Mode (DTM), Refer to "Scan Tool Testing/Output Diagnostic Test Mode (DTM) (Function 03)" Testing and Inspection
- Connect multimeter (voltage measurement range) between Ground (GND) and either left or right contact of the following fuses (only one fuse terminal voltage supply):

Fuse No. Specification for left or right contact
28 approx. battery voltage

If the specifications are not obtained:
- Check wiring.

If no malfunction is detected in wire:
- Replace Fuel Pump (FP) Relay -J17.
- Display readiness code Refer to "Scan Tool Testing/Monitors, Trips and/or Drive Cycle (Readiness Codes)/Displaying Readiness Code" Testing and Inspection. Readiness code must be generated if DTC memory was erased, Refer to "Scan Tool Testing/Monitors, Trips and/or Drive Cycle (Readiness Codes)/Generating Readiness Code" Testing and Inspection