Fuel Injectors, Checking
Fuel Injectors, Checking
The following test procedure is used to diagnose Fuel Injectors (N30, N31, N32, N33, N83, and N84).
Special tools, testers and auxiliary items required
• Multimeter.
• Diode test lamp (12V).
• Wiring diagram.
Test requirements
• Fuses for engine electronics OK.
• Parking brake engaged.
• Battery voltage at least 12.5 V.
• Vehicles with automatic transmission, shift selector lever into position "P" or "N".
• All electrical consumers such as, lights and rear window defroster, switched off (radiator fan must not run during test).
• A/C switched off.
• The fuel tank at least 1/4 full.
• Ignition switched off.
Test procedure
- Perform a preliminary check to verify the customer's complaint. Refer to => [ Preliminary Check ] Preliminary Check.
Right bank
- Disconnect the 6 pin electrical harness connector - 1 - for Fuel Injectors (N30, N31, N32) from the right rear of the engine.
Left bank
- Disconnect the 14 pin electrical harness connector - 3 - for Fuel Injectors (N33, N83, N84) from the left rear of the engine.
Checking internal resistance
- Using a Multimeter , check the fuel injector electrical terminals for resistance.
Right bank
Left bank
Specified value: 12 to 13 ohms (at room temperature)
• With an engine at operating temperature, the resistance of the fuel injectors increases by approx. 4 to 6 ohms.
If the specified value is not obtained:
- Replace the faulty fuel injector.
If the specified value is obtained:
Checking activation
- Connect a diode test lamp (12V) to the electrical harness connector terminals of the Fuel Injector to be tested.
Right bank
Left bank
- Operate the starter and test the activation of the Fuel Injector.
LED should flicker.
• LEDs 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 the ignition off.
If LED flickers:
- Replace the faulty Fuel Injector
If LED does not flicker:
Checking voltage supply
- Using a Multimeter, check the Fuel Injector electrical harness connector terminal to ground (GND) for voltage.
Right bank
Left bank
- Operate the starter briefly.
Specified value: Battery voltage.
- Switch the ignition off.
If the specification is not obtained:
- 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.
- Connect the Test Box 105 Pin (VAG1598/42) with Adapter Cable (1598/39-1).
If the manufacturers test box is not being used, perform the following step.
- Remove the Engine Control Module (ECM) (J623). Refer to=> [ Engine Control Module, Replacing ] Engine Control Module, Replacing
Right bank
Left bank
Using a Multimeter, check the Fuel Injector electrical harness connector terminals to the Engine Control Module (ECM) (J623)
Specified value: 1.5 ohms max
If the specification is not obtained:
- Check the wiring for a short circuit to Battery positive (+) or an open circuit.
- If necessary, repair the wiring connection.
If no malfunctions are found in wiring:
- Replace the Engine Control Module (ECM) (J623) => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.
- Assembly is performed in the reverse of the removal.
After repair work, the following work steps must be performed in the following sequence:
1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Mode 03 - Read DTC Memory.
2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.
3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.