DTC P0380 Federal RPO FE9, NG1
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 engine control module (ECM) controls the glow plug ON times by monitoring coolant temperature and glow plug voltage.
Conditions for Running the DTC
The ignition switch in the ON position.
Conditions for Setting the DTC
| • | The ECM has commanded glow plugs ON and the glow plug signal voltage is less than 4 volts. |
| or |
| • | The ECM has commanded glow plugs OFF and the glow plug signal voltage is more than 4 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
If the glow plug relay is stuck in the ON position, check for proper operation of the glow plugs, refer to Glow Plug System Diagnosis . When glow plugs are commanded ON by the scan tool, an internal ECM timer protects the glow plugs from damage by cycling them ON for 3 seconds and then 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 N·m (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 numbers below refer to the step numbers on the diagnostic table.
-
This step will determine if DTC P0380 is a hard failure.
-
This step determines if there is a relay control circuit or ECM fault that will not energize the relay.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
Confirm that the glow plugs are commanded OFF with the scan tool. Does the scan tool display glow plug feedback signal voltage present all the time? | -- | Go to Step 9 | Go to Step 3 | |
|
Important: The DMM may indicate a bias voltage on the circuit before the relay is energized. This is normal.
Does the voltage measure near the specified value when the relay is commanded ON? | B+ | Go to Step 4 | Go to Step 8 | |
4 |
Does the test lamp illuminate? | -- | Go to Step 5 | Go to Step 12 |
5 | Probe the ground circuit of the glow plug relay with a test lamp connected to battery voltage. Refer to Troubleshooting with a Test Lamp in Wiring Systems. Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 13 |
6 |
Does the test lamp illuminate when the scan tool commands the glow plugs ON? | -- | Go to Step 7 | Go to Step 17 |
7 |
Did you find a problem? | -- | Go to Step 14 | Go to Step 18 |
8 |
Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 18 |
9 |
Does the test lamp illuminate all of the time? | -- | Go to Step 10 | Go to Step 11 |
10 |
Does the test lamp illuminate? | -- | Go to Step 16 | Go to Step 20 |
11 | Probe the glow plug signal circuit at the harness connector with a test lamp connected to a good ground. Refer to Troubleshooting with a Test Lamp in Wiring Systems. Does the test lamp illuminate? | -- | Go to Step 15 | Go to Step 19 |
12 | Repair the open or short to ground in the battery positive voltage circuit to the glow plug relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 21 | -- |
13 | Repair the open in the glow plug relay ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 21 | -- |
14 | Repair the open or short to ground in the glow plug signal circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 21 | -- |
15 | Repair the short to voltage in the glow plug signal circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 21 | -- |
16 | Repair the short to voltage in glow plug relay control circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 21 | -- |
17 |
Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 19 |
18 |
Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 20 |
19 | Replace the glow plug relay. Refer to Glow Plug Relay Replacement . Did you complete the replacement? | -- | Go to Step 21 | -- |
20 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 21 | -- |
21 |
Does the DTC run and pass? | -- | Go to Step 22 | Go to Step 1 |
22 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
