Fuel Injectors, Checking

Fuel Injectors, Checking

Recommended special tools and equipment



- V.A.G1526A hand multimeter
- V.A.G 1527 B Voltage Tester
- V.A.G1594A connector test kit
- V.A.G1598/31 test box

Test requirements:
- Fuse for fuel injectors OK
- Fuel Pump (FP) Relay OK
- Ignition switched off.

NOTE: Voltage is supplied to the fuel injectors via the Fuel Pump (FP) relay.

Procedure





- Remove engine cover (arrows).

Checking internal resistance
- Disconnect harness connector at the fuel injector to be tested.






- Connect multimeter at valve for resistance measurement.
Specified value: 12 to 13 Ohms (at room temperature)

With an engine at operating temperature, the resistance increases by approx. 4 to 6 Ohms.

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

If specified value is obtained:

Checking voltage supply





- Connect e.g. V.A.G 1527 B voltage tester as follows:

Harness connector Terminal Measure to
1 Engine Ground (GND)

- Operate starter briefly.
- LED must light up.

- Switch ignition off.

If LED does not light up:
- Check wire connection from harness connector terminal 1 to Fuel Pump (FP) Relay -J17- via fuse for open circuit according to wiring diagram.
Specified value: Wire resistance max 1.5 Ohms

- If necessary, repair wire connection.

If LED lights up:

Checking activation

Test requirement:
- Internal resistance of valve OK
- Slide back rubber grommet of fuel injector connector, but leave connector connected.






- Connect voltage tester e.g. V.A.G 1527 B with measuring probes and connector adapters from V.A.G 1594 A between terminal 2 (signal) and terminal 1 (B+); the harness connector remains connected.
- Operate starter briefly.
- LED must blink.

NOTE: Voltage testers do not go out completely during low current pick-up between activations by the ECM, but rather continue to glow a little and then get slightly brighter during activation.

- Switch ignition off.

If LED does not blink:
- Connect test box to wiring harness of Engine Control Module (ECM). ECM is not connected.






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






Specified value: Wire resistance max 1.5 Ohms

- Check wires for short circuit to each other as well as to B+ and Ground (GND).
Specified value: Infinite Ohms (no continuity)

- If necessary, repair wire connection.

If no malfunctions are detected:
- Replace Engine Control Module (ECM).

Final procedures
After repair work, the following work steps must be performed in the mentioned sequence:
1. Check DTC memory.
2. If necessary, erase DTC memory.
3. Generate readiness code.

- End diagnosis and switch ignition off.