Test Notes

Output Functions

Glow Plug WAIT TO START Lamp - A lamp to indicate to the operator when the glow plugs have been on long enough to crank the engine. It is controlled by the PCM. WAIT TO START lamp ON time is a function of engine oil temperature, barometric pressure and battery voltage. ON time normally varies between 1 to 10 seconds.

NOTE: WAIT TO START light ON time is independent from glow plug relay ON time,

Detection/Management
An open or shorted to ground glow plug relay or WAIT TO START lamp circuit can be detected by an on-demand output circuit check performed during the KOEO standard test.

Glow plug and glow plug harness problems cannot be detected by the PCM.

CAUTION: Do not perform any voltage checks with the engine running; 115V DC at 10 amps present on injector circuits.

Enter this pinpoint test only when directed here from symptom flowcharts.

This pinpoint test is intended to diagnose only the following:
- Powertrain Control Module (PCM)
- harness circuits: WAIT TO START lamp
- warning lamp

Description
The glow plugs are energized during and after the WAIT TO START light is on. When the WAIT TO START light goes off, the engine is ready to be started.

DTC Description
P0381 = Glow plug indicator circuit malfunction