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Glow Plug System
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. 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 .8 volts. |
or
| • | PCM has commanded glow plugs OFF and voltage at the glow plugs is greater than .8 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
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 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 the OFF for 12 seconds.
Test Description
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 PCM is requesting the glow plug system ON.
-
This Step will determine if the glow plug relay has been activated, and out put voltage has been seen by the PCM.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Important: Before clearing DTCs use the scan tool Capture Info to record freeze frame and failure records for reference, as data will be lost when Clear Info function is used. Was the On-Board Diagnostic (OBD) System Check performed? | -- | ||
2 |
Does scan tool display 'Glow Plug System' enabled? | -- | ||
3 |
Does scan tool display 'Glow Plugs' at specified value? | B+ | ||
4 | DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids If additional DTCs were stored refer to those table(s). Were additional DTCs stored? | -- | Go to the Applicable DTC Table | Go to Diagnostic Aids |
5 |
Is test light 'ON'? | -- | ||
6 |
Is test light ON? | -- | ||
7 |
Is voltage at the specified value? | B+ | ||
8 |
Is test light ON when scan tool commands glow plugs ON? | -- | ||
9 | Check glow plug relay control circuit for a poor connection at the PCM and replace terminal if necessary. Did any terminals require replacement? | -- | ||
10 | Repair open or short to ground in glow plug relay ignition feed circuit. Is the action complete? | -- | -- | |
11 | Repair open or poor connections in glow plug relay ground circuit. Is the action complete? | -- | -- | |
12 |
Was a problem found? | -- | ||
13 | Check glow plug relay control circuit for a poor connection at the PCM and replace terminal if necessary. Was a problem found? | -- | ||
14 |
Was a problem found? | -- | ||
15 | Check glow plug relay signal circuit for a poor connection at the PCM and replace terminal if necessary. Was a problem found? | -- | ||
16 | Replace glow plug relay. Refer to Glow Plug Relay Replacement . Is the action complete? | -- | ||
17 | Replace the faulty PCM. Important: If the PCM is faulty, the new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | |
18 |
Does the scan tool indicate that this diagnostic Ran and Passed? | -- | ||
19 | Using the scan tool, select Capture Info, Review Info. Are any DTCs displayed that have not been diagnosed? | -- | Go to the Applicable DTC Table | System OK |
