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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 82 (Automatic Transmission Diagnosis - ALLISON) >> Diagnostic Tests >> DTC P0776/P1721: Solenoid "B" Controlled Clutch Stuck Off >> Diagnostic Procedure

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. Drive the vehicle under normal operating conditions. Make the shift determined in step  3. Using the scan tool, monitor engine, turbine, and output speed sensor readings. Is speed sensor data erratic or are signal dropouts detected? If so, see appropriate speed sensor DTC. If not, go to next step.
  5. Connect a pressure gauge to the line pressure tap. See HYDRAULIC PRESSURE TESTS  under PERFORMANCE TESTS. Using the scan tool in clutch test mode, cycle through all gear ranges with the engine at idle and vehicle brakes applied. Record line pressure in each gear range. Was the line pressure low in a specific gear range or in gear ranges where the same clutch was applied? If so, see SYMPTOM DIAGNOSIS  under TROUBLE SHOOTING. If not, go to next step.
    6. CAUTION: When using the scan tool to perform a clutch test in 4th or 5th gear, never exceed 1400 RPM under stall conditions (with brakes held), or transmission damage may occur.
  6. Conduct a clutch test for all forward gear ranges. See CLUTCH TEST  under PERFORMANCE TESTS. Did turbine speed remain at zero in all gear ranges? 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 next step. If not, go to step  9.
  8. Remove the transmission for overhaul or replacement. Is the overhaul or replacement complete? If so, go to step  11.
  9. Inspect for stuck or sticking trimmer valve. Was a valve problem found and repaired? If so, go to step  11. If not, go to next step.
  10. Replace solenoid "B". See SOLENOID VALVES  under REMOVAL & INSTALLATION. Is the replacement complete? Is solenoid replacement complete? If so, go to next step.
  11. Perform the following procedure to verify the repair:
    • Clear the DTC.
    • Use the scan tool to reset adaptive for all shifts.
    • 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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