Voltage Supply, Checking

Voltage Supply, Checking

Observe all safety precautions: => [ Safety Precautions ] Safety Precautions

View clean working conditions: => [ Clean Working Conditions ] Clean Working Conditions

Prior to repair work, perform a preliminary check to verify the condition. Refer to => [ Preliminary Check ] Preliminary Check.

Use only gold-plated terminals when servicing any component with gold-plated electrical harness connector terminals.

For wiring diagrams, component locations, and connector views, Refer to the applicable wiring diagram.

Special tools, testers and auxiliary items required

• Multimeter

• Wiring diagram

Test requirements

• Battery voltage at least 12.5 V

• Fuel pump relay OK

• Fuses OK

• Generator OK

• Ground connections between engine/transmission/chassis OK

Test procedure

- Remove the Engine Control Module (ECM) (J623). Refer to the service information for removal and installation procedures.

Checking the voltage supply circuits:

- Using a multimeter, measure the voltage of the Engine Control Module (ECM) (J623) voltage supply circuits. Refer to Wiring Diagrams.

- Switch the ignition on.

Specified value: 12.5 V

If the specified value was not obtained:

- Check the power supply circuits to the engine control module power supply relay for an open circuit, a short circuit or high resistance.

- Check the wiring connections for damage, corrosion, loose or broken terminals.

- Repair as necessary.

If no malfunctions are found in the wiring:

Checking the ground circuits:

- Using a multimeter, measure the resistance of the Engine Control Module (ECM) (J623) ground circuits. Refer to Wiring Diagrams.

Specified value: 1.5 ohms Max.

If the specification was not obtained:

- Check the circuit for an open circuit or high resistance.

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

- Repair as necessary.

If no malfunctions are found in the wiring and the voltage supply was OK:

Erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.

Generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.

- Perform a road test to verify any electrical repairs.

Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Modes 01 - 09.

If the fault does return and no malfunction is detected in the wiring and the voltage supply was OK:

- Replace the engine control module. Refer to the service information for removal and installation procedures.

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 Modes 01 - 09.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.