Glow Plug Control Module: Description and Operation

CAUTION: The glow plug system is a 7 volt system. DO NOT ATTEMPT to test the glow plug system with a 12V power source or damage will occur.

Glow Plug Module:

The glow plug module is mounted to the inner fender between the battery and the master cylinder in the engine compartment.

CAUTION: The glow plug system is a 7 volt system. DO NOT ATTEMPT to test the glow plug system with a 12V power source or damage will occur.

Glow Plug Module:

When the ignition (key) switch is placed in the ON position, a signal is sent from the sensors to the ECM relaying current engine coolant temperature and ambient air temperature.

After receiving this signal, the ECM will determine if, when and for how long of a period the glow plugs should be activated. This is done before, during and after the engine is started. Whenever the glow plug module is activated, it will control the 7 volt high amperage circuit for the operation of the four glow plugs.

The Glow Plug lamp is tied to this circuit. Lamp operation is also controlled by the ECM.

With a cold engine, the glow plug module and glow plugs may be activated for a maximum time of 200 seconds. Refer to the following Glow Plug Control chart for a temperature/time comparison of the glow plug relay operation.

Glow Plug Control Chart:

In this chart, Pre-Heat and Post-Heat times are mentioned. Pre-Heat is the amount of time the glow plug control circuit is activated when the ignition (key) is switched ON, without the engine running. Post-Heat is the amount of time the glow plug control circuit is activated after the engine is operated. The Glow Plug lamp will not be activated during the post-heat cycle.