Fuel Injectors, Testing

Fuel Injectors, Checking

Special tools, testers and auxiliary items required
- Multimeter.
- Diode test lamp (12 V).
- Wiring diagram.

Test requirements
- Fuel Injector Fuse OK.
- Motronic Engine Control Module (ECM) J220 Fuse OK.
- Motronic Engine Control Module (ECM) Power Supply Relay J271 OK.
- Battery voltage at least 12.5 volts.
- All electrical consumers such as, lights and rear window defroster, switched off.
- Vehicles with automatic transmission, shift selector lever into position "P" or "N".
- A/C switched off.
- Ground (GND) connections between engine/transmission/chassis OK.
- Ignition switched off.
- Observe safety precautions.
- Observe rules for cleanliness.

Test procedure
- Perform a preliminary check to verify the customers complaint. General Diagnosis

Start diagnosis







- Remove the Fuel Injector electrical harness retaining screws - arrows -.







- Remove the Fuel Injector electrical harness - arrows - from the fuel rail.
- Disconnect the Fuel Injector electrical harness connectors -1,2,3,4,5,6 - from the Fuel Injectors.

Checking internal resistance







- Using a multimeter, check the Fuel Injector electrical terminals 1 to 2 for resistance.

Specified value: 12.0 to 20.0 Ohms (at approx. 20 degrees C)

If the specified value was not obtained:
- Replace the faulty Fuel Injector.

If the specified value was obtained:

Checking activation







- Connect a diode test lamp (12V) to the electrical harness connector terminals 1 and 2 of the Fuel Injector to be tested.
- Operate the starter and test the activation of the Fuel Injector.

LED should flicker.
- Switch the ignition off.

If LED flickers:
- Replace the faulty Fuel Injector.

If LED does not flicker:

Checking voltage
- Using a Multimeter, check the Fuel Injector electrical harness connector terminal 1 to ground (GND) for voltage.
- Operate the starter.

Specified value: Battery voltage.

If the specification is not obtained:







- Check the wiring from the Fuel Injector electrical harness connector terminal 1 to the Battery (+) 1 in the interior wiring harness for a short circuit to Ground (GND), or an open circuit.
- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
- If necessary, repair the wiring connection.

If no malfunctions are found in the wiring:

Checking wiring
If the manufacturers test box is being used. Perform the following step.
- Install the test box VAG1598/31.

If the manufacturers test box is not being used. Perform the following step.
- Remove the Motronic Engine Control Module (ECM) J220.







- Using a Multimeter, check the Fuel Injector electrical harness connector terminals to the Motronic Engine Control Module (ECM) J220 electrical harness connector terminals for resistance.







Specified value: 1.5 Ohms Max.

If the specification is not obtained:
- Check the wiring for a short circuit to each other, Battery (+), and Ground (GND).
- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring:
- Erase the DTC memory. Diagnostic Mode 04 - Erase DTC Memory
- Perform a road test to verify repair.

If the DTC does not return:
Repair complete, Generate readiness code. Readiness Code
- End diagnosis.

If the DTC does return and no malfunction is detected in the wiring and the voltage supply was OK:
- Replace the Motronic Engine Control Module (ECM) J220.
- Assembly is performed in the reverse of the removal.

Final procedures
After repair work, the following work steps must be performed in the following sequence:
1. Check the DTC memory. Diagnostic Mode 03 - Read DTC Memory
2. If necessary, erase the DTC memory. Diagnostic Mode 04 - Erase DTC Memory
3. If the DTC memory was erased, generate readiness code.

End of diagnosis