Refer to
DIESEL PCM, GLOW PLUGS, FUSE-RELAY
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 PCM controls the glow plug ON times by monitoring coolant temperatures and glow plug voltage. This is a type B code.
Conditions for Setting the DTC
| • | PCM has commanded glow plugs ON and voltage at the glow plugs is less than 4.0 volts. |
or
| • | PCM has commanded glow plugs OFF and voltage at the glow plugs is greater than 4.0 volts. |
or
| • | PCM has commanded glow plugs ON and there is more than a 2 volt difference between glow plug voltage and ignition voltage. |
Action Taken When the DTC Sets
The MIL will be illuminated after 2 test failures.
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 glow plug relay is stuck in the ON position, check for proper operation of glow plugs, refer to Glow Plug System Check . 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 the 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 number(s) below refer to the Step number(s) on the Diagnostic Table.
-
This Step will determine if P0380 is a hard failure.
-
This Step will determine if the PCM is requesting the glow plug system is ON.
-
This Step will determine if the glow plug relay has been activated and the output voltage has been seen by the PCM.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Important: Before clearing the DTCs, use the Scan Tool Capture Info in order to record the Freeze Frame and the failure records for reference, as the data will be lost when the Clear Info function is used. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
Does the Scan Tool display the Glow Plug System as enabled? | -- | |||
Does the Scan Tool display the Glow Plugs at the specified value? | B+ | |||
4 | Does the Scan Tool display Glow Plug voltage present all the time? | -- | ||
5 | The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids If any additional DTCs were stored, refer to those table(s). Were there any additional DTCs stored? | -- | Go to the Applicable DTC Table | Go to Diagnostic Aids |
6 |
Is the test light ON? | -- | ||
7 |
Is the test light ON? | -- | ||
Is the voltage at the specified value? | B+ | |||
9 |
Is the test light ON when the Scan Tool commands the glow plugs ON? | -- | ||
10 | Repair an open or a short to ground in glow plug relay ignition feed circuit. Is the action complete? | -- | -- | |
11 | Repair any open or poor connections in the glow plug relay ground circuit. Is the action complete? | -- | -- | |
12 |
Was a problem found? | -- | ||
13 | Check the glow plug relay control circuit for a poor connection at the PCM and replace the terminal if necessary. Was a problem found? | -- | ||
14 |
Was a problem found? | -- | ||
15 | Check the glow plug relay signal circuit for a poor connection at the PCM and replace the terminal if necessary. Was a problem found? | -- | ||
16 |
Is the test light ON all the time? | -- | ||
17 | Repair the short to voltage on the glow plug relay control circuit. Is the action complete? | -- | -- | |
18 | Replace the glow plug relay. Refer to Glow Plug Relay Replacement . Is the action complete? | -- | -- | |
19 | Replace the PCM. Important: The new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | |
20 |
Does the Scan Tool indicate that this diagnostic Passed? | -- | ||
21 | Use the Scan Tool in order to select Capture Info, Review Info. Are there any DTCs displayed that have not been diagnosed? | -- | Go to the Applicable DTC Table | System OK |
