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Diagnostic Procedure

WARNING: This page is about a different car, the 2002 GMC Cab & Chassis Sierra and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Check for applicable service bulletins before proceeding with this test. Perform this test only if there is a driveability complaint or if you have been directed to this table from another section in the service information.
NOTE: Do not turn the ignition off when performing this diagnostic procedure. Do not clear the DTCs unless instructed by this diagnostic procedure.
  1. Turn ignition on, engine off. Does the scan tool turn on? If so, go to next step. If not, scan tool or vehicle body control system is at fault.
  2. Is the MIL on? If so, go to next step. If not, MIL control circuit may be at fault. Diagnose as necessary.
  3. Attempt to establish communication with the PCM. Does the scan tool communicate with the PCM? If so, go to next step. If not, scan tool may be at fault. Diagnose as necessary.
    4. NOTE: Diagnostic Trouble Codes (DTC), engine performance, and transmission default actions can greatly affect the transmission performance. Ensure that these items are not the cause of a transmission concern.
  4. Use the scan tool CAPTURE INFO function to save or capture (store information) any DTC information. Are there any DTCs present? If so, see DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If not, see SYMPTOM DIAGNOSIS  under TROUBLE SHOOTING.
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