Fuel Pump Relay and Activation, Checking
Fuel Pump Relay and Activation, Checking
Special tools, testers and auxiliary items required
• (VAG1526A)
• (VAG1594A)
• (VAG1598/31)
• (VAS5051) with (VAS5051/1)
The fuel pump and certain components of the injection system are supplied with power by way of the Fuel Pump (FP) relay (J17).
The Fuel Pump (FP) relay (J17) is only energized when the engine is running, i.e. the relay is only connected to Ground (via the engine control module) when engine speed pulses are detected in the engine control module.
Test requirements
• Battery voltage at least 12.7 V
Functional check of fuel pump relay
- Remove driver's storage compartment.
- Connect testing and information system (VAS5051 ) => [ VAS 5051, Connecting and Select Functions ] VAS 5051, Connecting and Select Functions and select vehicle system " 01 Engine electronics" in selection. Ignition must be switched on.
- Initiate final control diagnosis. Refer to => [ Output Diagnostic Test Mode ] Output Diagnostic Test Mode and actuate Evaporative Emission (EVAP) canister purge regulator valve (N80).
• Fuel pump relay (on the 9-unit-relay carrier in the driver's footwell on the left, position 1) should pull and fuel pump should run.
A - If relay does not respond:
- Check voltage supply of fuel pump relay.
- Check activation of fuel pump relay.
B - If relay is energized but fuel pump does not run:
- Check voltage supply for fuel pump and components (via fuel pump relay).
Checking voltage supply of fuel pump relay
- Disconnect fuel pump relay.
- Connect multimeter as follows to measure voltage.
• Specified value: approx. battery voltage
- Connect multimeter as follows to measure voltage:
- Switch ignition on.
• Specified value: approx. battery voltage
If the specified values are not obtained:
- Check wiring connections.
If specifications are obtained:
Checking activation of fuel pump relay
- Switch ignition off.
- Reconnect relay.
- Connect test box (VAG1598/31) to wiring harness for engine control module; do not connect engine control module. Refer to => [ Wiring and Component Check with Test Box VAG 1598/31 ] Wiring and Component Check With Test Box VAG 1598/31.
- Bridge terminals 1 and 65 at test box with leads from adapter kit (VAG1594A).
- Switch ignition on.
• Fuel pump relay (on the 9-unit-relay carrier in the driver's footwell on the left, position 1) should pull and fuel pump should run.
If the relay responds now, but not during final control diagnosis:
- Replace engine control module. Refer to => [ Engine Control Module without Metal Anti-Theft Housing ] Engine Control Module Without Metal Anti-Theft Housing.
If the relay does not respond:
- Switch ignition off.
- Disconnect cable link.
- Disconnect fuel pump relay.
- Check for open circuit and short to positive or Ground in following wiring connection:
- Repair any open/short circuit as necessary.
If no DTC is found:
- Replace Fuel Pump (FP) relay (J17).
- Reconnect engine control module.
Checking voltage supply of fuel pump and components
- Disconnect fuses (S228), (S229 ) and (S234) (positions 28, 32 and 34) in fuse holder.
- Initiate final control diagnosis. Refer to => [ Output Diagnostic Test Mode ] Output Diagnostic Test Mode and actuate evaporative emission (EVAP) canister purge regulator valve (N80).
- To measure voltage, connect multimeter to Ground and to one terminal of following fuses in fuse holder.
If the specified values are not obtained:
- Repeat test at other terminal of fuse base.
If the specifications are still not obtained:
- Check wiring connections.
If no DTC is found:
- Replace fuel pump (FP) relay (J17).
- Reinsert fuses.