Glow Plug System: Description and Operation

Glow Plug Control System:

PURPOSE
The glow plug control circuit applies power to the glow plugs, which heat the combustion chambers so that the diesel engine can be started.

OPERATION
The solid-state glow plug controller, attached to the top of the engine block, controls the glow plug pre-glow and after-glow time. It also controls the circuit's operation by sensing engine temperature, glow plug voltage and after-glow voltage from the start/run circuit.

When the ignition switch is turned to run, voltage from maxi-fuse K is applied through the glow plug controller to the wait-to-start indicator lamp.

The glow plugs heat up in zero to fifteen seconds, depending on engine coolant temperature. After the glow plugs heat up, the controller cycling switch opens and turns the wait-to-start indicator lamp off. The glow plugs are now warm enough for the engine to be started.

At the same time the ignition switch is turned to run, voltage from maxi-fuse K is applied to the after-glow timer (located inside the glow plug controller). The after-glow timer cycles the glow plugs for up to two minutes, depending on engine temperature. The after-glow timer then opens. The wait-to-start indicator lamp will not light during the after-glow period.

If the ignition switch is turned off, it can be turned on immediately, and the glow plug heating cycle will start again.

CONSTRUCTION
The system consists of eight glow plugs (one for each cylinder), a solid-state controller/power relay assembly, two fusible links (one for each bank of four glow plugs), a "wait-to-start" warning lamp, and a wiring harness.