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HOMESERVICE MANUALSCHEVROLET2001CHEVY EXPRESS G3500, VAN PASSENGER EXTENDED, 6.5 FREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 138 (ENGINE CONTROLS - THEORY & OPERATION - 2.2L)SELF-DIAGNOSTICSDESCRIPTIONNOTES
2001 Chevrolet Chevy Express G3500, Van Passenger Extended, 6.5 F

Section 138 (Engine Controls - Theory & Operation - 2.2L): Self-Diagnostics: Description: Notes

2001 Chevrolet Chevy Express G3500, Van Passenger Extended, 6.5 FSECTION Notes
WARNING: This page is about a different car, the 2003 Pontiac Sunfire, 2003 Pontiac Grand Am, 2003 Oldsmobile Alero, and 2003 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.

The PCM is equipped with a self-diagnostic system which detects system failures or abnormalities. When a malfunction occurs, PCM will illuminate the Malfunction Indicator Light (MIL) located on instrument cluster. When a malfunction is detected and MIL is illuminated, a corresponding Diagnostic Trouble Code (DTC) will be stored in PCM memory. Malfunctions are designated as either "emission related" or "non-emission related", and are divided into 4 code types to identify type of fault. The 3 code types are defined as follows:

  • Type "A"

    Emission related faults that illuminate MIL at first occurrence of a fail condition.

  • Type "B"

    Emission related faults that illuminate MIL if a fault occurs in 2 consecutive ignition cycles.

  • Type "C"

    Non-emission related faults that do not illuminate MIL. Driver Information Center (DIC) may display a message.

Emission related DTCs (type "A" or "B") cause MIL to illuminate and remain on until the malfunction is repaired. If MIL illuminates and remains on during vehicle operation, the cause of the malfunction must be determined using affected DTC, located in appropriate SELF-DIAGNOSTICS article. PCM records and updates failure records/operating conditions to Freeze Frame. If a sensor fails, PCM will use a substitute value in its calculations to continue engine operation. In this condition, vehicle is functional but impaired driveability is likely. Use a scan tool to clear codes and turn off MIL.

Non-emission related DTCs (type "C") do not illuminate the MIL, but may display a message on the Driver Information Center (DIC), if equipped. The corresponding DTC, however, will be retained in PCM memory. PCM records operating conditions at time of failure into memory. If related fault does not reoccur within 40 warm-up cycles, related diagnostic trouble code will be erased from PCM memory. Intermittent failures may be caused by a sensor, connector or wiring related problem. See appropriate TROUBLE SHOOTING - NO CODES article.

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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.