Fuel Injectors, Checking

Check Fuel Injectors

Recommended special tools and equipment







- VAG1526A multimeter
- V.A.G 1527 B Voltage Tester
- VAG1594A connector test kit
- VAG1598/31 test box

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

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

Procedure

Cylinder bank 2 (left):







- Remove front engine cover (arrows).







- Disconnect harness connector at Intake Manifold Change-Over Valve -N156- -Item 1-.

Continuation for both cylinder banks:







- Disconnect all harness connectors at fuel injectors of the respective cylinder bank, to do this disengage harness connectors at the bottom -arrow-

Checking internal resistance







- Connect multimeter at valve for resistance measurement.
- Specified value: 11 ... 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 Measure to
Terminal
1 Engine Ground (GND)

- Switch ignition on.
- 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







- 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 (engine can also start).
- 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. Test Box, Connecting For Wiring Testing







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







- Specified value: Wire resistance max 1.5 Ohms
- Also check wires for short circuit to each other as well as to B+ and Ground (GND).
- Specified value: Infinity 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, Diagnostic mode 3 - Check DTC memory. Diagnostic Mode 3: Check DTC Memory
2 - Erase DTC memory, diagnostic 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.