With Generic Scan Tool

Needle Lift Sensor, Checking

The needle lift sensor signal determines the start of injection during normal operation by closed-loop control based on RPM, load and temperature. If the sensor malfunctions, control switches to open-loop, based on RPM and load.

The Needle Lift Sensor (G80) is part of the cylinder 3 Fuel Injector and cannot be serviced separately.

Special tools, testers and auxiliary items required

• Multimeter.

• Wiring diagram.

Test requirements

• The Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) (J248) fuses OK.

• Battery voltage at least 12.5 volts.

• All electrical consumers such as, lights and rear window defroster, switched off.

• A/C switched off.

• Ground (GND) connections between engine/transmission/chassis OK.

• Ignition switched off.

Test procedure

- Perform a preliminary check to verify the customers complaint. Refer to => [ Preliminary Check ] .

Start diagnosis

- Disconnect the Needle Lift Sensor (G80) electrical harness connector - 1 -.





Checking internal resistance

- Using a multimeter, check the Needle Lift Sensor (G80) terminals 1 to 2 for resistance.

Specified value: 80 to 120 ohms

If the specified value was not obtained:

- Replace cylinder 3 Fuel Injector.

If the specified value was obtained:

Checking wiring

If the manufacturers test box is being used, perform the following step.

- Install the test box. Refer to => [ 68 Pin Test Box Adapter, Installing ] .

If the manufacturers test box is not being used, perform the following step.

- Remove the Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) (J248). Refer to => [ Engine Control Module, Replacing ] .

- Using a Multimeter, check the Needle Lift Sensor (G80) electrical harness connector terminals to the Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) (J248) electrical harness connector T80 terminals for resistance.









Specified value: 1.5 ohms Max.

If the specification was not obtained:

- Check the wiring for a short circuit to each other, Battery (+), and Ground (GND).

- If necessary, repair the faulty wiring connection.

- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

If no malfunction is detected in the wiring:

- Erase the DTC memory. Refer to => [ 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 ] .

- End diagnosis.

If the DTC does return and no malfunction is detected in the wiring and the voltage supply was not OK:

- Replace the Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) (J248). Refer to => [ Engine Control Module, Replacing ] .

- Assembly is performed in the reverse of the removal.

Final procedures

After the 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 ] .

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] .

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] .

End of diagnosis