With Generic Scan Tool

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

Recommended special tools and equipment







- VAG1526A hand multimeter
- VAG1594A connector test kit
- VAG1598/31 test box

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 requirements:
- Battery voltage at least 12.7 V
- Ignition switched off.

Function test of Fuel Pump (FP) relay
- Remove driver-side storage compartment:
- Connect test box to wiring harness of Engine Control Module (ECM) ; ECM is not connected. Test Box, Connecting For Wiring Test
- Bridge terminals 1 and 65 at test box using wires e.g. from V.A.G 1594 A adapter test kit.
- Switch ignition on.







- 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 Fuel Pump (FP) runs:
- Check voltage supply of Fuel Pump (FP) relay.
- Checking activation of Fuel Pump (FP) relay.

B - If 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 for voltage measurement as follows.

Central electronics in driver-side Measure to
footwell, left, position 4
Terminal
17 Chassis Ground (GND)

- Specified value: approx. battery voltage

If specified value is not obtained:
- Replace central electronics.
- Connect multimeter for voltage measurement as follows:

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

- Switch ignition on.
- Specified value: approx. battery voltage
- Switch ignition off.

If specified value is not obtained:
- Check wire connections for open circuit according to wiring diagram:
- Specified value: Wire resistance max 1.5 Ohms

If specified values are obtained:

Checking activation of Fuel Pump (FP) relay
- Remove cable bridge.
- Remove Fuel Pump (FP) relay.
- Connect test box to wiring harness of Engine Control Module (ECM); ECM is not connected. Test Box, Connecting For Wiring Test







- Check the following wire connection for open circuit according to wiring diagram:

Central electronics in driver-side Test box
footwell, left, position 4
Terminal Socket
16 65

- Specified value: Wire resistance max 1.5 Ohms
- Also check the wire for short circuit to B+ and Ground (GND).
- Specified value: infinity Ohms (no continuity)
- If necessary, repair wire connection.

If no malfunctions are detected:
- Replace Fuel Pump (FP) Relay -J17-.
or
- Replace 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.
- Connect multimeter for voltage measurement to Ground (GND) and to one terminal of the following fuses in the fuse holder.
- Operate starter briefly.

Fuse 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 for open circuit according to wiring diagram:
- Specified value: Wire resistance max 1.5 Ohms

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

Final procedures
After repair work, the following work steps must be performed in the mentioned sequence:
1 - Check DTC memory "Mode 3: Check DTC memory". Diagnostic Mode 3: Check DTC Memory
2 - If necessary, erase DTC memory "Mode 4: Reset/erase diagnostic data". Diagnostic Mode 4: Reset/Erase Diagnostic Data
3 - Generate readiness code. Readiness Code, Generating

- End diagnosis and switch ignition off.