Fuel Injectors, Checking
Fuel Injectors, Checking
The following test procedure is used to diagnose Fuel Injectors (N30, N31, N32, N33, N83, N84).
Special tools, testers and auxiliary items required
• Multimeter.
• Diode test lamp (12V).
• Wiring diagram.
Test requirements
• Fuse (SC21) OK.
• Fuse (SC29) OK.
• Power Supply Relay (terminal 50) (J682) 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. Diagnostic Mode 09 - Read Vehicle Information.
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° 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.
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.
- Using a Multimeter, check the Fuel Injector electrical harness connector terminals to the Engine Control Module (ECM) (J623) electrical harness connector T40 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. Refer to => [ Diagnostic Mode 04 - Erase 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. Refer to => [ Readiness Code Description ] Diagnostic Mode 09 - Read Vehicle Information.
- End diagnosis.
If the DTC does return and no malfunction is detected in the wiring and the voltage supply was OK:
- Replace the Engine Control Module (ECM) (J623). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.
- 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. 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 ] Engine.
End of diagnosis