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Home >> Buick >> 2007 >> Lucerne CX >> Repair and Diagnosis >> External Pages >> Different car >> Section 36 (Battery, Charging System And Starting System) >> Diagnostic Information and Procedures >> DTC P0621 >> Conditions for Clearing the MIL/DTC

Conditions for Clearing the MIL/DTC

WARNING: This page is about a different car, the 2005 Buick LaCrosse and 2005 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
DTC P0621

Step Action Value Yes No
Schematic Reference: Starting and Charging Schematics 
Connector End View Reference: Engine Electrical Connector End Views 
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2
  1. Install a scan tool.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
  3. Using the scan tool, observe the Specific DTC Information for DTC P0621 until the test runs.
Does the scan tool indicate that DTC P0621 has passed this ignition cycle?		 - Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems Go to Step 3 
3
  1. Install a scan tool.
  2. Start the engine.
  3. Turn OFF all accessories, including headlamps.
  4. With a scan tool, observe the Ignition 1 Signal parameter in the PCM data list.
Does the scan tool indicate that the voltage is above the specified value?		 13 V Go to Step 4  Go to Step 5 
4
  1. Turn OFF the ignition.
  2. Disconnect the generator harness connector.
  3. Turn the ignition ON, with the engine OFF.
  4. Measure and record voltage between the generator turn on signal circuit and a good ground.
  5. Start the engine.
  6. Measure the voltage between the generator turn on signal circuit and a good ground.
Is the voltage less than the first value with the generator OFF and greater than the second value with the generator ON?		 0 V
5 V		 Go to Step 7  Go to Step 6 
5 Test the battery positive voltage circuit of the generator for a high resistance or open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 10  Go to Step 7 
6 Test the generator turn on signal circuit for a short or open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 10  Go to Step 8 
7 Inspect for poor connections at the harness connector of the generator. Refer to Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 10  Go to Charging System Test 
8 Inspect for poor connections at the harness connector of the powertrain control module (PCM). Refer to Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 10  Go to Step 9 
9
IMPORTANT: The replacement PCM must be programmed
Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.Did you complete the replacement?		 - Go to Step 10  -
10
  1. Review and record the scan tool Failure Records data.
  2. Use the scan tool in order to clear the DTC.
  3. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
  4. Using the scan tool, observe the Specific DTC Information for DTC P0621 until the test runs.
Does the scan tool indicate that DTC P0621 failed this ignition?		 - Go to Step 3  System OK
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