Glow Plug System: Testing and Inspection

Diagnostic Procedures

Cylinder Pressure Sensor Checking

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

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

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

- The Cylinder Pressure Sensor is located within the Glow Plug and is not serviceable separately.

• The Glow plug terminal/connector is not repairable. The harness must be replaced if damaged.

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 volts.

• Ground connections between engine/transmission/chassis OK.

• Ignition switched off.

Start diagnosis

- Remove the Engine Control Module (ECM) (J623).

- Using a multimeter, check the following Engine Control Module (ECM) (J623) circuits for resistance with the Cylinder Internal Pressure Sensor (glow plug) connected. Connect the RED ohm meter lead to T60/36. Connect the BLACK ohm meter lead to the corresponding sensor terminal listed in the chart below.

• Polarity of the ohm meter leads MUST be correct or an error in the readings will occur leading to misdiagnosis.





Specified values: 4.0 Mohms. (±.5 Mohms)

If the specified value was not obtained:

- Switch the Glow Plug with the faulty reading to a Glow plug that has a correct reading, reinstall in engine and retest for resistance on the circuit. If reading is now in range, replace the faulty Glow Plug. If the reading is still out of range, the harness will have to be replaced.

If the specified values in the above tests were obtained:

- Replace the Engine Control Module (ECM) (J623).

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 ] 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.