P0380

DTC P0380 Glow Plug Circuit Performance






Circuit Description

The glow plug system is used to assist in providing the heat required to begin combustion during engine starting at cold ambient 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 coolant temperatures and glow plug voltage. The PCM also monitors glow plugs individually to detect a failure. Once a failure has been detected, a diagnostic signal is sent to the PCM so the diagnostic code and MIL can be activated. This is a type B code.

Action Taken When the DTC Sets

Hard start or no start and possible white smoke.

Conditions for Clearing the MIL/DTC

^ The PCM will turn the MIL off after three consecutive trips without a fault condition.
^ A History DTC will clear when forty consecutive warm-up cycles that the diagnostic does not fail (coolant temperature has risen 5°C (40°F) from start up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle).
^ Use of a Scan Tool.

Diagnostic Aids

IF a P0380 DTC sets after the PCM has been flashed, the glow plug system must be relearned. Refer to (LINK-GOTO-REPAIR-609502) Glow Plug System Type Relearn. If glow plug relay is stuck in the "ON" position, check for proper operation of glow plugs. When 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 then "OFF" for 12 seconds. The glow plug relay battery feed wire nut should be tested for proper torque. The California glow plug system will send the following voltages.






Test Description

Number(s) below refer to the number(s) on the diagnostic table.

3-This step will determine if 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 the PCM are working properly.

11-This step will determine if if there is a short to voltage an the relay control circuit.

13-This step will determine if the glow plugs or the glow plug harness is causing the P0380 DTC.