Technical Description of OBD-II Trouble Code
“B” Glow Plug/Heater Circuit
What does that signify?
This code is a generic powertrain code that applies to all makes and models of vehicles (1996-newer). However, the specific repair steps may vary slightly depending on the model.
For GM vehicles, the description is slightly different: Glow Plug Performance Conditions.
The glow plug is activated when starting a cold diesel engine. The powertrain control module (PCM) uses the coolant temperature to determine this. The glow plug heats up to increase the cylinder temperature, making it easier for the diesel fuel to ignite. If there is an open in the glow plug or circuit, this DTC will be triggered.
On some diesel engines, the PCM will continue to operate the glow plugs for a period of time after the engine is running to reduce white smoke and engine noises.
A typical diesel engine glow plug:
In essence, the P0382 code indicates a fault in the glow plug/heater circuit “B” as detected by the PCM.
Note: This DTC is very similar to P0380, which refers to circuit “A”. If multiple DTC codes are present, they should be addressed in the order they appear.
Symptoms
The symptoms of a P0382 trouble code may include:
Malfunction Indicator Lamp (MIL) illumination
Glow plug / Wait To Start indicator stays illuminated longer than normal (may be on solid)
Difficulty starting, especially in colder weather
Potential Causes
The potential causes for this DTC may include:
Faulty glow plug wiring (open, short to ground, etc.)
Defective glow plug
Blown fuse
Malfunctioning glow plug relay
Faulty glow plug module
Diagnostic Steps & Possible Solutions
If you have a GM truck or any other vehicle, check for known issues such as TSBs (technical service bulletins) related to this code.
Inspect associated fuses and replace any that are blown. Test the glow plug relay if possible.
Visually examine the glow plugs, wiring, and connectors for corrosion, bent/loose wiring pins, loose screws/nuts on wiring connections, or any signs of damage. Repair as necessary.
Check the resistance of harness connectors using a digital volt ohm meter (DVOM) and compare the readings to manufacturer specifications.
Disconnect the glow plug wires and measure their resistance using a DVOM. Compare the readings to the specified values.
Use a DVOM to verify that the glow plug wiring connector is receiving power and ground.
If replacing a glow plug, start by hand-threading it into the threads, similar to a spark plug.
If you want to test the glow plug, you can remove them, apply 12V to the terminal, and ground the body for 2-3 seconds. If the glow plug glows red hot, it is functioning properly. If it appears dull red or does not glow at all, it is faulty.
If you have access to an advanced scan tool, there may be specific functions related to the glow plug wiring circuit that you can utilize.
Other Glow Plug related DTCs: P0380, P0381, P0383, P0384, P0670, P0671, P0672, P0673, P0674, P0675, P0676, P0677, P0678, P0679, P0680, P0681, P0682, P0683, P0684.
