P0380

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION
The glow plug system is used in order to assist in providing the heat required to begin combustion during cold engine temperatures. The glow plugs are heated before and during cranking, as well as initial engine operation. The PCM controls the glow plug ON times by monitoring the coolant temperatures and the glow plug voltage. This is a type B DTC.

CONDITIONS FOR SETTING THE DTC
^ The PCM has commanded the glow plugs ON and the voltage at the glow plugs is less than 4.0 volts.
OR
^ The PCM has commanded the glow plugs OFF and the voltage at the glow plugs is greater than 4.0 volts.
OR
^ The PCM has commanded the glow plugs ON and there is more than a 2 volt difference between the glow plug voltage and the ignition voltage.

ACTION TAKEN WHEN THE DTC SETS
A hard start or no start and possible white smoke.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM will turn the Malfunction Indicator Lamp (MIL) OFF after three consecutive trips without a fault condition.
^ A History DTC will clear after forty consecutive warm-up cycles during which the diagnostic does not fail (coolant temperature has risen 5°C (40°F) from the start up coolant temperature and the engine coolant temperature exceeds 71°C (160°F) during that same ignition cycle.
^ Use of a Scan Tool will clear the DTC codes.

DIAGNOSTIC AIDS
If the glow plug relay is stuck in the ON position, check for a proper operation of the glow plugs, refer to Glow Plug System Check. System Check - Glow Plugs
When the glow plugs are commanded ON by the Scan tool, an internal PCM timer protects the glow plugs from damage by cycling them ON for 3 seconds and OFF for 12 seconds.
The glow plug output feed wire nut and battery feed wire nut at the relay should be checked for proper torque (5 Nm (44 lb in) and for corrosion.
An intermittent may be caused by the following:
^ Poor connections.
^ Rubbed through wire insulation.
^ Broken wire inside the insulation.

TEST DESCRIPTION
The number(s) below refer to the Step number(s) on the Diagnostic Table.
2. This Step will determine if P0380 is a hard failure.
3. This Step will determine if the PCM is requesting the glow plug system is ON.
7. This Step will determine if the glow plug relay has been activated and the output voltage has been seen by the PCM.