Fuel Pump Relay: Testing and Inspection

Fuel Pump (FP) Relay -J17- And Activation, Checking







Special tools and equipment
- VAG1526A
- VAG1594A
- VAG1598/31
- VAS5051 with VAG5051/1
- or
- VAG1551 with VAG1551/3A

Voltage is supplied to the Fuel Pump (FP) and several components of the injection system via the Fuel Pump (FP) relay -J17-.

Engine must be turning for Fuel Pump (FP) relay -J17- to close. This means that the relay does not receive Ground (GND) (via ECM) until the ECM recognizes RPM signals.

Test requirement:
- Battery voltage at least 12.7 V

Function test of Fuel Pump (FP) relay
- Remove driver-side storage compartment.
- Connect VAS5051 tester or VAG1551 scan tool and select control module for engine electronics using "address word" 01. Ignition must remain switched on. Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks" Testing and Inspection
- Initiate output Diagnostic Test Mode (DTM) and activate Evaporative Emission (EVAP) canister purge regulator valve -N80-. Refer to "Scan Tool Testing/Output Diagnostic Test Mode (DTM) (Function 03)" Testing and Inspection







- Fuel Pump (FP) relay (at position 4 of central electrics in driver's footwell, left) must trigger and Fuel Pump (FP) must run.

A - If relay does not trigger:
- Check voltage supply of Fuel Pump (FP) relay.
- Checking activation of Fuel Pump (FP) relay.

B - If relay triggers, but Fuel Pump (FP) does not run:
- Check voltage supply for Fuel Pump (FP) and components (via Fuel Pump -FP- relay).

Check voltage supply of Fuel Pump (FP) relay
- Remove Fuel Pump (FP) relay.







- Connect multimeter to terminal 17 of relay socket and Ground (GND) for voltage measurement.
- Specification: approx. battery voltage

If specified value is not obtained:
- Replace central electrics.

Checking activation of Fuel Pump (FP) relay
- Switch ignition off.
- Connect VAG1598/31 test box at wiring harness to Engine Control Module (ECM), do not connect ECM. Refer to "Scan Tool Testing/Wiring and Component Testing Using VAG1598/31 Test Box", Testing and Inspection
- Switch ignition on.
- Bridge terminals 1 and 65 at test box using wires from VAG1594A adapter test kit.







- Fuel Pump (FP) relay (at position 4 of central electrics in driver's footwell, left) must trigger.

If relay triggers now, but didn't during output DTM:
- Replace Engine Control Module (ECM).

If relay does not trigger:
- Switch ignition off.
- Remove cable bridge.
- Remove Fuel Pump (FP) relay.







- Connect multimeter for voltage measurement as follows.

Central electronics in Measure to
driver-sidefootwell, left,
position 4
Terminal
19 Engine Ground (GND)

- Switch ignition on.
- Specification: approx. battery voltage

If specified value is not obtained:
- Check wire connections.

If specified value is obtained:
- Check following wire connection for open circuit and short circuit to Ground (GND) and B+:

Central electronics in VAG1598/31 test box
driver-side footwell, left,
position 4
Terminal Socket
16 65

- Repair open circuit or short circuit if necessary.

If no malfunctions are detected:
- Replace Fuel Pump (FP) relay -J17-.
- Re-connect Engine Control Module (ECM).

Check voltage supply for Fuel Pump (FP) and components







- Remove fuses S228, S232, and S234 (positions 28, 32, and 34) from fuse holder.
- Initiate output Diagnostic Test Mode (DTM) and activate Evaporative Emission (EVAP) canister purge regulator valve -N80-. Refer to "Scan Tool Testing/Output Diagnostic Test Mode (DTM) (Function 03)" Testing and Inspection
- Connect multimeter for voltage to Ground (GND) and to one terminal of following fuses in fuse holder.

Circlip Specified value at one of the terminals
S228 approx. battery voltage
S232 approx. battery voltage
S234 approx. battery voltage

If specified values are not obtained:
- Repeat test at another terminal of fuse socket.

If specified values are not obtained again:
- Check wire connections.

If no malfunctions are detected:
- Replace Fuel Pump (FP) relay -J17-.
- Re-insert fuses.