P0380 (California)

CIRCUIT DESCRIPTION
The glow plug system is used 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 coolant temperature and glow plug voltage. The California Glow Plug system has eight individual glow plug supply circuits between the controller and the glow plugs. If the feedback voltage from the controller to the PCM is not within range, DTC P0380 will set.

CONDITIONS FOR RUNNING THE DTC
The ignition is ON.

CONDITIONS FOR SETTING THE DTC
^ The glow plugs are commanded OFF and the glow plug feedback is more than 2.0 volts.
or
^ The glow plugs are commanded ON and the glow plug feedback is not between 5.0 volts and 6.2 volts.

ACTION TAKEN WHEN THE DTC SETS
^ The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
^ The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
^ A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
^ Clear the MIL and the DTC with a scan tool.

DIAGNOSTIC AIDS

IMPORTANT: If the glow plug relay is stuck in the ON position, check for proper operation of the glow plugs. When the glow plugs are commanded ON by the scan tool, an internal powertrain control module (PCM) timer protects the glow plugs from damage by cycling them ON for 3 seconds and the OFF for 12 seconds. The glow plug relay battery feed wire nut at the relay should be tested for proper torque. The California glow plug system will send the following voltages, or signals to the PCM.




An intermittent may be caused by the following:
^ Poor connections, terminal tension
^ Rubbed-through wire insulation
^ Broken wire inside the insulation
^ A short to battery positive voltage on the glow plug relay control circuit

TEST DESCRIPTION

Steps 1-11:

Steps 12-22:

Steps 23-29:

The numbers below refer to the step numbers on the diagnostic table.
3. This step will determine if diagnostic trouble code (DTC) P0380 is a hard failure.
4. This step will determine if there is a short to voltage on the signal circuit.
8. This step will determine if there is ignition voltage at the glow plug relay.
10. This step will determine if the glow plug control circuit and PCM are working properly.
11. This step will determine if there is a short to voltage on the relay control circuit.
13. This step will determine if the glow plugs or the glow plug harness is causing the DTC P0380.