Pinpoint Test S: Glow Plugs & Relay: Description
Glow plug relay controls current flow to glow plugs. Glow plug relay ON time is controlled by Powertrain Control Module (PCM) and is a function of engine oil temperature, barometric pressure and battery voltage. Glow plug ON time is 10-120 seconds. Glow plug WAIT TO START light indicates to operator when glow plugs have been on long enough to crank engine. It is controlled by PCM. WAIT TO START light ON time is a function of engine oil temperature, barometric pressure and battery voltage. ON time normally is 1-10 seconds. DTC 0380 indicates glow plug circuit malfunction.
Perform this test when directed here by QUICK TEST. This PINPOINT TEST is intended to diagnose:
- Glow plug relay.
- Wiring harness circuit; (GP/RELAY coil).
- Powertrain Control Module (PCM).
An open or shorted to ground glow plug relay or WAIT TO START light circuit can be detected by performing a KOEO OUTPUT STATE SELF-TEST. See KOEO OUTPUT STATE SELF-TEST under QUICK TEST.
Glow plug relay control signal is used to control glow plug relay to cycle glow plugs for assisting engine start-up. Glow plugs will be operated at low ambient temperature and/or high altitude. At colder temperatures, glow plugs ON time is extended. At high battery voltage, duty cycle is reduced to prevent plug damage. For low barometric pressure, ON time is extended to assist start/drive-away.