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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1044 (Engine Controls Diagnosis - 6.6L (Lb7) (DTCS P0237 To P0611)) >> Diagnosis >> DTC P0380 (Federal RPO FE9, NG1) >> Test Description

Test Description

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The numbers below refer to the step numbers on the diagnostic table.

  1. 2:  This step will determine if DTC P0380 is a hard failure.
  2. 3:  This step determines if there is a relay control circuit or ECM fault that will not energize the relay.
DTC P0380 (Federal RPO FE9, NG1)

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  Engine Control Module (ECM) Connector End Views  or  Engine Controls Connector End Views 
1 Did you perform the Diagnostic System Check-Engine Controls? - Go to Step 2  Go to Diagnostic System Check - Engine Controls
2  Confirm that the glow plugs are commanded OFF with the scan tool.
Does the scan tool display glow plug feedback signal voltage present all the time?		 - Go to Step 9  Go to Step 3 
3 
IMPORTANT: The DMM may indicate a bias voltage on the circuit before the relay is energized. This is normal.
  1. Turn ON the ignition, with the engine OFF.
  2. Disconnect the glow plug relay.
  3. Probe the glow plug relay control circuit at the glow plug relay harness connector with a DMM connected to ground. Refer to Troubleshooting with a Digital Multimeter in Wiring Systems.
  4. Command the glow plug relay ON with a scan tool.
Does the voltage measure near the specified value when the relay is commanded ON?		 B+ Go to Step 4  Go to Step 8 
4
  1. Turn ON the ignition, with the engine OFF.
  2. Probe the battery positive voltage circuit of the glow plug relay with a test lamp that is connected to a good ground. Refer to Troubleshooting with a Test Lamp in Wiring Systems.
Does the test lamp illuminate?		 - Go to Step 5  Go to Step 12 
5 Probe the ground circuit of the glow plug relay with a test lamp connected to battery voltage. Refer to Troubleshooting with a Test Lamp in Wiring Systems.
Does the test lamp illuminate?		 - Go to Step 6  Go to Step 13 
6
  1. Reconnect the glow plug relay.
  2. Turn ON the ignition, with the engine OFF.
  3. Probe the glow plug signal circuit at the glow plug relay connector with a test lamp connected to a good ground.
  4. Command the glow plug relay ON and OFF with a scan tool.
Does the test lamp illuminate when the scan tool commands the glow plugs ON?		 - Go to Step 7  Go to Step 17 
7
  1. Turn OFF the ignition.
  2. Disconnect the ECM. Refer to Engine Control Module (ECM) Replacement .
  3. Test the glow plug signal circuit for an open or short to ground.
Did you find a problem?		 - Go to Step 14  Go to Step 18 
8
  1. Test the glow plug relay control circuit for an open or short to ground.
  2. If the glow plug relay control circuit is open or shorted to ground, repair as necessary. Refer to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 21  Go to Step 18 
9
  1. Disconnect the glow plug relay connector. Refer to Glow Plug Relay Replacement (Federal Emissions) or Glow Plug Relay Replacement (California Emissions) .
  2. Turn ON the ignition, with the engine OFF.
  3. Probe the glow plug relay control circuit with a test lamp connected to a good ground. Refer to Troubleshooting with a Test Lamp in Wiring Systems.
Does the test lamp illuminate all of the time?		 - Go to Step 10  Go to Step 11 
10
  1. Turn OFF the ignition.
  2. Disconnect the ECM. Refer to Engine Control Module (ECM) Replacement .
  3. Turn ON the ignition.
  4. Probe the glow plug relay control circuit with a test lamp connected to a good ground. Refer to Troubleshooting with a Test Lamp in Wiring Systems.
Does the test lamp illuminate?		 - Go to Step 16  Go to Step 20 
11 Probe the glow plug signal circuit at the harness connector with a test lamp connected to a good ground. Refer to Troubleshooting with a Test Lamp in Wiring Systems.
Does the test lamp illuminate?		 - Go to Step 15  Go to Step 19 
12 Repair the open or short to ground in the battery positive voltage circuit to the glow plug relay. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 21  -
13 Repair the open in the glow plug relay ground circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 21  -
14 Repair the open or short to ground in the glow plug signal circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 21  -
15 Repair the short to voltage in the glow plug signal circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 21  -
16 Repair the short to voltage in glow plug relay control circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 21  -
17
  1. Check for poor connections at the glow plug relay. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 21  Go to Step 19 
18
  1. Check for poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 21  Go to Step 20 
19 Replace the glow plug relay. Refer to Glow Plug Relay Replacement (Federal Emissions) or Glow Plug Relay Replacement (California Emissions) .
Did you complete the replacement?		 - Go to Step 21  -
20 Replace the ECM. Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 - Go to Step 21  -
21
  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC run and pass?		 - Go to Step 22  Go to Step 1 
22 With a scan tool, observe the stored information, Capture Info.
Does the scan tool display any DTCs that you have not diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List System OK
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