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HOMESERVICE MANUALSCHEVROLET2001CAVALIER LS, 2.4 TREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 200 (BATTERY, CHARGING SYSTEM AND STARTING SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC P0621CONDITIONS FOR CLEARING THE MIL/DTC
2001 Chevrolet Cavalier LS, 2.4 T

Conditions for Clearing the MIL/DTC

2001 Chevrolet Cavalier LS, 2.4 TSECTION Conditions for Clearing the MIL/DTC
WARNING: This page is about a different car, the 2004 Pontiac Sunfire and 2004 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
  • The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
  • The DTC can be cleared by using the scan tool Clear DTC Information function.
DTC P0621

Step Action Values Yes No
Schematic Reference: Starting and Charging Schematics 
Connector End View Reference: Engine Controls Connector End Views in Engine Controls - 2.2L (L61) or Engine Electrical Connector End Views 
1 Did you perform the Engine Electrical Diagnostic System Check? - Go to Step 2  Go to Diagnostic System Check - Engine Electrical 
2
  1. Install a scan tool.
  2. Start the engine.
  3. With a scan tool, observe the GEN - F Terminal Signal parameter in the PCM data list.
Does the scan tool indicate that the GEN - F Terminal parameter is within the specified range?		 5-100% Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems Go to Step 3 
3
  1. Turn OFF the ignition.
  2. Disconnect the generator harness connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage between the generator turn on signal circuit of the generator harness connector and a good ground.
Is the voltage within the specified range?		 4.5 - 5.5 V Go to Step 5  Go to Step 4 
4 Test the generator turn on signal circuit for a short to ground or open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 8  Go to Step 6 
5 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 8  Go to Charging System Test 
6 Inspect for poor connections at the harness connector of the ECM. Refer to Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 8  Go to Step 7 
7
IMPORTANT: The replacement PCM must be programmed.
Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement in Engine Controls - 2.2L (L61).Did you complete the replacement?		 - Go to Step 8  -
8
  1. Review and record the scan tool Fail Records data.
  2. Use the scan tool in order to clear the DTC.
  3. Operate the vehicle within the Conditions for Running DTC P0621 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?		 - Go to Step 2  System OK
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.