DTC P0380 Californiaand RPO NF4, VCL
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. The California Glow Plug system has eight individual glow pllug supply circuits between the controller and the glow plugs. If the feedback voltage from the controller to the ECM 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 engine control module (ECM) 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 ECM:
Signal Voltage | Glow Plugs Failed Open |
|---|---|
5.00-6.00 | None |
2.00-3.00 | 1 |
1.00-2.00 | 2 |
0.80-1.70 | 3 |
Less than 1.3 | 4 or more |
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
The numbers below refer to the step numbers on the diagnostic table.
-
This step will determine if diagnostic trouble code (DTC) P0380 is a hard failure.
-
This step will determine if there is a short to voltage on the signal circuit.
-
This step will determine if there is ignition voltage at the glow plug relay.
-
This step will determine if the glow plug control circuit and ECM are working properly.
-
This step will determine if there is a short to voltage on the relay control circuit.
-
This step will determine if the glow plugs or the glow plug harness is causing the DTC P0380.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | -- |
2 |
Important : If this DTC set after an ECM reflash.
Does the scan tool display the Glow Plug System Type as California? | -- | Go to Step 3 | Go to DTC P0380 |
Does the scan tool display the glow plug feedback voltage parameter is within the specified range? | 5.0-5.6 V | Go to Step 7 | Go to Step 4 | |
Does the scan tool display a glow plug feedback voltage parameter more than the specified value? | 5.6 V | Go to Step 20 | Go to Step 5 | |
5 | Does the scan tool display a glow plug feedback voltage parameter more than the specified value? | 0.45 V | Go to Step 10 | Go to Step 6 |
6 |
Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 23 |
7 | The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If any additional DTCs were stored, refer to those tables. Were there any additional DTCs stored? | -- | Go to Diagnostic Aids | |
Does the test lamp illuminate? | -- | Go to Step 9 | Go to Step 15 | |
9 |
Does the test lamp illuminate? | -- | Go to Step 10 | Go to Step 16 |
Does the test lamp illuminate with the scan tool command ON? | -- | Go to Step 12 | Go to Step 11 | |
Does the test lamp illuminate all of the time? | -- | Go to Step 22 | Go to Step 17 | |
12 |
Does the glow plug parameter voltage measure near the specified value? | Battery Voltage | Go to Step 13 | Go to Step 19 |
Does the test lamp illuminate for each circuit? | -- | Go to Step 25 | Go to Step 14 | |
14 |
Does each glow plug illuminate the test lamp? | -- | Go to Step 25 | Go to Step 24 |
15 | Repair an open or a short to ground in the glow plug relay ignition 1 voltage circuit. Did you complete the repair? | -- | Go to Step 28 | -- |
16 | Repair the open circuit or poor connections in the glow plug relay harness ground circuit. Did you complete the repair? | -- | Go to Step 28 | -- |
17 | Inspect the glow plug relay control circuit for an open or short to ground and repair as necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 28 | Go to Step 18 |
18 | Inspect the glow plug relay control circuit for a proper connection at the ECM and replace the terminal if necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 28 | Go to Step 27 |
19 | Inspect the glow plug relay signal circuit for an open or short to ground and repair as necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 28 | Go to Step 26 |
20 | Inspect the glow plug relay signal circuit for a proper connection at the ECM and replace the terminal if necessary. Did you find an improper connection and make the necessary replacement? | -- | Go to Step 28 | Go to Step 21 |
21 | Inspect for a short to voltage in the glow plug relay signal circuit and repair as necessary. Refer to Wiring Repairs in Wiring Systems. Did you find the improper condition? | -- | Go to Step 28 | Go to Step 25 |
22 | Inspect for a short to voltage in the glow plug control circuit and repair as necessary. Refer to Wiring Repairs in Wiring Systems. Did you find the improper condition? | -- | Go to Step 28 | Go to Step 27 |
23 | Repair the open or poor connection on the battery voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 28 | -- |
24 | Replace any glow plug that did not illuminate the test lamp. Did you complete the replacement? | -- | Go to Step 28 | -- |
25 | Inspect for an open or poor connection in the glow plug harness. Refer to Wiring Repairs in Wiring Systems. Did you find and correction the condition? | -- | Go to Step 28 | Go to Step 26 |
26 | Replace the glow plug relay. Refer to Glow Plug Relay Replacement . Did you complete the replacement? | -- | Go to Step 28 | -- |
27 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 28 | -- |
28 |
Does the DTC run and pass? | -- | Go to Step 29 | Go to Step 2 |
29 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK |
