Go to
Glow Plug Controls
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 PCM controls the glow plug ON times by monitoring the coolant temperatures and the glow plug voltage. This is a type B DTC.
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 greater 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
A 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 after forty consecutive warm-up cycles during which the diagnostic does not fail (coolant temperature has risen 5°C (40°F) from the start up coolant temperature and the engine coolant temperature exceeds 71°C (160°F) during that same ignition cycle. |
| • | Use of a Scan Tool will clear the DTC codes. |
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 (5N·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
Number(s) below refer to the Step number(s) on the Diagnostic Table.
-
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 Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
2 |
Is test light ON? | -- | ||
Does scan tool display Glow Plugs at specified value? | B+ (± 2.0V) | |||
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? | -- | ||
Is voltage at the specified value? | B+ | |||
8 |
Is test light ON when scan tool commands glow plugs ON? | -- | ||
9 | Repair the open in the battery feed circuit. Is action complete. | -- | -- | |
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 repair performed? | -- | ||
14 |
Was a repair performed? | -- | ||
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 the glow plug relay. Refer to Glow Plug Relay Replacement . Is the action complete? | -- | ||
17 | Replace the 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 |
