Fuel Pump Relay-J17 and Relay Activation, Checking
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 fuel pump relay is located in the electronics box in the front passenger's footwell (central electrics unit, relay position 4).
- Connect vehicle diagnostic, testing and information system VAS5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01". Connecting VAS 5051 Scan Tool
When doing this the ignition must be switched on.
- Start output Diagnostic Test Mode (DTM). Output Diagnostic Test Mode (DTM) (Function 03)
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.
Testing activation of fuel pump relay
- Switch ignition off.
- Connect VAG1598/31 test box to wiring harness for engine control unit. Do not connect to engine control module itself. Connecting VAG 1598/31 Test Box
- Connect sockets 65 and 2 of test box to each other using test leads from VAG1594 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 hand-held 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 VAG1598/31 test box
in passenger's footwell
(right), relay
position 4
terminal Socket
16 65
- Repair any open/short circuit as necessary.
If no malfunction is detected in the wire:
- Replace Fuel Pump (FP) Relay -J17.
- Display readiness code. Readiness Code Checking
The readiness code must be regenerated if the DTC memory was erased. Readiness Code, Generating
Checking activation for fuel pump and components
- Remove fuse cover on A-pillar in footwell on right side.
- Remove fuses 1, 2 and 3 (in blue fuse carrier, 4th row from the top).
- Start output Diagnostic Test Mode (DTM). Output Diagnostic Test Mode (DTM) (Function 03)
- Connect hand-held 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
1 approx. battery voltage
2 approx. battery voltage
3 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. The readiness code must be regenerated if the DTC memory was erased.
Readiness Code Checking
Readiness Code, Generating