P0380 Glow Plug Feedback Circuit (Federal)

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

Refer to Engine Controls Schematics.

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 Powertrain Control Module (PCM) controls the glow plug ON times by monitoring the coolant temperatures and the glow plug voltage.

CONDITIONS FOR RUNNING THE DTC
The ignition is in the ON position.

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 more 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
^ The PCM illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive drive trip the diagnostic runs and fails.
^ The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the Failure Records store this information. If the diagnostic reports a failure on the second consecutive drive trip, the Freeze Frame Records the operating conditions at the time of failure and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM will turn the MIL off after 3 consecutive trips without a fault condition.
^ A history DTC clears after 40 consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
^ The scan tool Clear Info function was used.

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. 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 of 5 N.m (44 lb in) and for corrosion. Component Tests and General Diagnostics

An intermittent may be caused by the following:
^ Poor connections
^ Rubbed through wire insulation
^ Broken wire inside the insulation

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table:
2. This step determines if P0380 is a hard failure.
3. This step determines if the PCM is requesting the glow plug system is ON.
8. This step determines if the glow plug relay has been activated and the output voltage has been seen by the PCM.