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Diagnostic Procedure

WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the diagnostic system check? If so, go to next step. If not, see DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  2. Check the transmission fluid level. See appropriate AUTOMATIC article in TRANSMISSION SERVICING. Is the transmission fluid level correct? If so, go to next step. If not, see appropriate AUTOMATIC article in TRANSMISSION SERVICING.
  3. Install the scan tool. Turn ignition on, engine off. Record the DTC failure records. Start the engine. Using the scan tool, check ignition voltage. Is the voltage 9-18 volts? If so, go to next step. If not, see DTC P0562: SYSTEM VOLTAGE LOW  or DTC P0563: SYSTEM VOLTAGE HIGH  .
  4. Install the scan tool. Monitor the Reverse gear ratio. Is the ratio 4.49:1? If so, go to next step. If not, see DIAGNOSTIC AIDS .
  5. Turn ignition on. Start the engine and run at idle. Using the scan tool, monitor engine, turbine, and output speed readings in Reverse with the vehicle brakes applied. Is noise indicated on the output speed sensor or turbine speed sensor data? If so, see appropriate speed sensor DTC. If not, go to next step.
    6. CAUTION: When using the scan tool to perform a clutch test in Reverse, never exceed 1000 RPM under stall conditions (brakes held), or transmission damage may occur.
  6. Apply vehicle brakes and place gearshift lever in Reverse. With engine at idle and Reverse attained, turbine speed should go to zero. Using the scan tool, monitor turbine speed while increasing engine speed to 1000 RPM. Did turbine speed remain at zero? If so, see DIAGNOSTIC AIDS . If not, go to next step.
  7. Remove the dipstick and inspect the transmission fluid for clutch debris or burnt odor. If necessary, drain a small amount of fluid for this inspection. Are there signs of a clutch failure? If so, go to step  9. If not, go to next step.
  8. Using the scan tool, monitor turbine speed while selecting 1st gear. If turbine speed is ever greater than zero after 1st gear is attained, there may be a problem with solenoid "A" or trimmer valve "A". If shift to 1st gear is harsh and delayed, there may be a problem with solenoid "B" or trimmer valve "B". Remove the control valve body, and inspect for stuck or sticking trimmer valves. If valves are moving freely, replace either solenoid "A" or "B" based on the shift characteristics described. See SOLENOID VALVES  under REMOVAL & INSTALLATION. Is replacement complete? If so, go to step  10.
  9. Remove the transmission for overhaul or replacement. Is replacement complete? If so, go to next step.
  10. Perform the following procedure to verify the repair:
    • Clear the DTC.
    • Operate the vehicle in all gear ranges under normal driving conditions.

    Did the DTC return? If so, go to step  1. If not, system is okay.

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