DTC P0380 Glow Plug Feedback Circuit Federal
Refer to Engine Controls Schematics
Glow Plug Controls--Federal Emissions
.
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.
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 determines if P0380 is a hard failure.
-
This step determines if the PCM is requesting the glow plug system is ON.
-
This step determines if the glow plug relay has been activated and the output voltage has been seen by the PCM.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 |
Important: Before clearing the DTCs, use the scan tool Capture Info to save the Freeze Frame and Failure Records for reference. The data in the control module is deleted once the Clear Info function is used. Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | |
Does the scan tool display the Glow Plug System as Enabled for 3 seconds? | -- | Go to Step 3 | Go to Step 8 | |
Does the scan tool display the Glow Plugs at the specified value? | B+ | Go to Step 4 | Go to Step 6 | |
4 | Does the scan tool display glow plug voltage present all the time? | -- | Go to Step 16 | Go to Step 5 |
5 | The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids If any additional DTCs are stored, refer to those tables. Were there any additional DTCs stored? | -- | Go to the applicable DTC table | Go to Diagnostic Aids |
6 |
Is the test lamp ON? | -- | Go to Step 7 | Go to Step 10 |
7 |
Is the test lamp ON? | -- | Go to Step 8 | Go to Step 11 |
Is the voltage at the specified value? | B+ | Go to Step 9 | Go to Step 12 | |
9 |
Is the unpowered test lamp ON when the scan tool commands the glow plugs ON? | -- | Go to Step 14 | Go to Step 18 |
10 | Repair an open or a short to ground in glow plug relay ignition feed circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 21 | -- |
11 | Repair any opens or poor connections in the glow plug relay ground circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 21 | -- |
12 |
Did you perform a repair? | -- | Go to Step 21 | Go to Step 13 |
13 | Check the glow plug relay control circuit for a poor connection at the PCM and replace the terminal if necessary. Refer to Wiring Repairs in Wiring Systems. Did you perform a repair? | -- | Go to Step 21 | Go to Step 20 |
14 |
Did you perform a repair? | -- | Go to Step 21 | Go to Step 15 |
15 | Check the glow plug relay signal circuit for a poor connection at the PCM and replace the terminal if necessary. Refer to Wiring Repairs in Wiring Systems. Did you perform a repair? | -- | Go to Step 21 | Go to Step 20 |
16 |
Is the test lamp ON all the time? | -- | Go to Step 17 | Go to Step 19 |
17 | Repair the short to voltage on the glow plug relay control circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 21 | -- |
18 | Inspect for poor connections in the glow plug relay. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 21 | -- |
19 | Replace the glow plug relay. Refer to Glow Plug Relay Replacement . Is the action complete? | -- | Go to Step 21 | -- |
20 | Replace the PCM. Important: The new PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | Go to Step 21 | -- |
21 |
Does the scan tool indicate the diagnostic Passed? | -- | Go to Step 22 | Go to Step 2 |
22 | Does the scan tool display any additional undiagnosed DTCs? | -- | Go to the applicable DTC table | System OK |
DTC P0380 Glow Plug Feedback Circuit California
Diagnostic Aids
Important: If a P0380 DTC sets after the PCM has been flashed, the glow plug system must be relearned. Refer to Glow Plug System Type Relearn . 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 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 (signal) to the PCM:
Signal Voltage | Glow Plugs |
|---|---|
5.0-5.6 | None |
2.3-2.8 | 1 |
1.3-1.8 | 2 |
0.8-1.4 | 3 |
Less than 1.1 | 4 or more |
An intermittent may be caused by the following:
| • | Poor connections (terminal tension) |
| • | 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 determines if P0380 is a hard failure.
-
This step determines if there is a short to voltage on the signal circuit.
-
This step determines if there is ignition voltage at the glow plug relay.
-
This step determines if the glow plug control circuit and PCM are working properly.
-
This step determines if there is a short to voltage on the relay control circuit.
-
This step determines if the glow plugs or the glow plug harness is causing the P0380.
-
This step ensures that the replacement PCM, which utilizes an electrically erasable programmable read only memory (EEPROM), is programmed when installed.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 |
Important: Before clearing the DTCs, use the scan tool Capture Info to save the Freeze Frame and Failure Records for reference. The data in the control module is deleted once the Clear Info function is used. Did you perform the On-Board Diagnostic (OBD) System Check ? | -- | Go to Step 2 | -- |
2 |
Important : Perform this step if the DTC set after a PCM reflash.
Does the scan tool display the Glow Plug System Type as California? | -- | Go to Step 3 | |
Does the DMM display a voltage near the first specified value with the glow plug command ON and near the second specified value with the glow plug commanded OFF? | 5.0-5.6 V 0.9-1.5 V | Go to Step 7 | Go to Step 4 | |
Does the scan tool display a glow plug voltage more than the specified value? | 5.6 V | Go to Step 21 | Go to Step 5 | |
5 | Does the scan tool display a glow plug voltage more than the specified value? | 0.3 V | Go to Step 10 | Go to Step 6 |
6 |
Is the test lamp ON? | -- | Go to Step 8 | Go to Step 25 |
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 the applicable DTC table | Go to Diagnostic Aids |
Is the test lamp ON? | -- | Go to Step 9 | Go to Step 16 | |
9 |
Is the test lamp ON? | -- | Go to Step 10 | Go to Step 17 |
| 9-12 V 0 V | Go to Step 12 | Go to Step 11 | |
Is the voltage equal to or more than the specified value all the time? | 1.0 V | Go to Step 23 | Go to Step 18 | |
12 |
Is the voltage at the specified value? | 5.0-5.6 V | Go to Step 21 | Go to Step 13 |
Does each circuit turn ON the test lamp? | -- | Go to Step 26 | Go to Step 14 | |
14 |
Does each glow plug illuminate the test lamp? | -- | Go to Step 26 | Go to Step 25 |
15 |
Is the test lamp OFF at each of the circuits? | -- | Go to Step 20 | Go to Step 27 |
16 | Repair an open or a short to ground in the glow plug relay ignition feed circuit. Did you complete the repair? | -- | Go to Step 30 | -- |
17 | Repair any opens or poor connections in the glow plug relay ground circuit. Did you complete the repair? | -- | Go to Step 30 | -- |
18 |
Did you find and correct the condition? | -- | Go to Step 30 | Go to Step 19 |
19 | Inspect the glow plug relay control circuit for a proper connection at the PCM and replace the terminal if necessary. Did you find an improper connection and make the necessary replacement? | -- | Go to Step 30 | Go to Step 29 |
20 |
Did you find and correct the condition? | -- | Go to Step 30 | Go to Step 28 |
21 | Inspect the glow plug relay signal circuit for a proper connection at the PCM and replace the terminal if necessary. Did you find an improper connection and make the necessary replacement? | -- | Go to Step 30 | Go to Step 22 |
22 | Test for a short to voltage in the glow plug relay signal circuit. Did you find the improper condition? | -- | Go to Step 30 | Go to Step 28 |
23 | Test for a short to voltage in the glow plug control circuit. Did you find and correct the condition? | -- | Go to Step 30 | Go to Step 29 |
24 | Repair the open or poor connection on the battery feed circuit. Did you complete the repair? | -- | Go to Step 30 | -- |
25 | Replace any glow plug that did not illuminate the test lamp. Did you complete the replacement? | -- | Go to Step 30 | -- |
26 | Repair the open or poor connections in the glow plug harness. Did you complete the repair? | -- | Go to Step 30 | -- |
27 | Repair the short to ground in the glow plug harness. Did you complete the repair? | -- | Go to Step 30 | -- |
28 | Replace the glow plug relay. Did you complete the replacement? | -- | Go to Step 30 | -- |
|
Important: The new PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to Step 30 | -- | |
30 |
Does the scan tool indicate the diagnostic Passed? | -- | Go to Step 31 | Go to Step 2 |
31 | Does the scan tool display any additional undiagnosed DTCs? | -- | Go to the applicable DTC table | System OK |
