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

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 and select vehicle system "01 - Engine electronics". Ignition must remain switched on for this. Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/VAS 5051 Tester, Connecting and Selecting Functions" Testing and Inspection
- Initiate output Diagnostic Test Mode (DIM) and activate Evaporative Emission (EVAP) canister purge regulator valve -N80-.







- Fuel Pump (FP) relay (at position 4 of central electronics 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 electronics.

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/Wire 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 electronics 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
driverside footwell,
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 the following wire connection for open circuit and short circuit to Ground (GND) and B+:







- 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 measurement to Ground (GND) and to one terminal of the following fuses in the fuse holder.







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 the fuses.