Electrical Checks

CHECKING ELECTRICAL RESISTANCE

- Disconnect harness connector from fuel injector to be tested.

Fuel Injector Testing:

- Measure resistance of fuel injector.

Specification:
Bosch 15.0-17.0 ohms
Siemens 13.5-14.5 ohms

If the specified value is not obtained:
- Replace fuel injector.

CHECKING BATTERY POSITIVE VOLTAGE FOR FUEL INJECTORS

REQUIREMENTS
^ Fuel pump relay OK
^ Activation of fuel pump relay OK
^ Injector valve circuit breaker -S72- OK (red holder in electronics box in passenger side footwell)

PROCEDURE

- Disconnect harness connector from fuel injector to be tested.

2-Pin Connector:

- Connect US 1115 LED tester or equivalent between connector terminal 2 and Ground (GND).
- Use On-Board Diagnostics (OBD) Output Diagnostic Test Mode (DTM) to activate fuel pump relay -J17-.
^ LED must light up

If the LED does not light up:
- Check wiring connection for continuity between connector terminal 2 and circuit breaker -S72- (red holder in electronics box in passenger side footwell) according to wiring diagram.
- Repair if necessary.

If the LED lights up:
- Check activation of fuel injectors.

CHECKING ACTIVATION OF FUEL INJECTORS

- Disconnect harness connector on fuel injector to be tested.
- Connect LED tester to connector terminal 1 and to battery positive (B+), or jumper to positive (B+) using cable from VW1594 connector test kit.
- Operate starter briefly (the engine can also turn over).
^ LED must blink

If the LED does not blink:
- Check wiring and connections between connector terminal 1 (for fuel injector being tested) and ECM as follows:
- Connect VAG 1598 test box with VAG 1598/12 adapter harness on wiring harness to ECM.
- Harness connector is not connected to ECM.

Injector Circuit Test Connections:

- Check control wire for continuity between fuel injector connector terminal 1 (in engine compartment) and test box.

ECM And Injector Connectors:

- If necessary, eliminate break or short circuit in wiring between terminal 1 of fuel injector being tested, and corresponding terminal at ECM connector -D-.

Terminal 1 on fuel Terminal on
injector connector ECM connector D
for cylinder number:

1 4
2 5
3 6
4 9
5 10
6 13

If, in the previous test above, the LED does not flash for any of the fuel injectors:
- Check voltage supply for ECM.

If voltage supply is OK:
- Replace ECM.