14. Glow Plug System Operation

14. GLOW PLUG SYSTEM OPERATION

NOTE: The wait to start indicator on time (1-10 seconds) is independent from glow plug on time.

Purpose:
The purpose of this test is to verify the glow plug system operation.

Glow Plug System Operation

- Glow Plug Control Module (GPCM) Operation







- Glow plug on time is dependent on oil temperature and altitude. The GPCM commands the glow plugs on for 1 to 120 seconds. The GPCM does not operate if the oil temperature is above 55°C (131°F).
- Connect the scan tool. Access and retrieve the KOEO and continuous DTCs. If GPCM DTCs are present, GO to Pinpoint Test AF. Tests AF: Glow Plug System
- Verify B+ voltage is supplied to the GPCM.
- Access and monitor the GPLTM and ECT PIDS to verify sufficient glow plug ON time.
- Turn the key to the ON position and measure the glow plug voltage (ON time).

- Glow Plug Resistance







- Disconnect the glow plug bus bar connector.
- Measure the resistance between the glow plug bus bar connector, component side and battery ground.
- Disconnect the GPCM.
- Measure the resistance between the GPCM connector, harness side and the glow plug bus bar connector, harness side.

Recommended Procedure:

Part 1:

Part 2:

NOTE:
- Check for poor connections or loose fitting pins.
- Incorrect measurements result if all glow plug connectors are not disconnected.

The glow plug monitor self-test is a KOER functional test of the glow plug system. The self-test is carried out on-demand with the engine running and the A/C off. The PCM activates the GPCM which monitors the glow plugs. The pedal may be used to increase the engine speed to increase voltage if needed. For fault detection, the self-test requires a fault present at the time of testing.

Possible Causes:
- GPCM power circuits
- Glow plugs
- Glow plug bus bar
- GPCM
- Circuitry

Tools Required:
- Digital Multimeter (DMM)
- Scan tool