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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 37 (Automatic Transmission - ALLISON - Service, Diagnosis & Troubleshooting) >> Transmission Does Not Shift Properly

Transmission Does Not Shift Properly

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Transmission Does Not Shift Properly

Condition Action
Engine idle speed too fast during NEUTRAL to range shift Adjust to correct idle speed.
Faulty throttle sensor/circuit Repair or replace the sensor or circuit.
Faulty or sticking bleed ball in 1-2-3-4 clutch piston housing Repair the transmission.
Excessive clutch running clearance Rebuild the transmission and adjust clearances.
Shift adaptives not converged Refer to FastLearn Procedure .
Instrument panel tachometer incorrect Repair or replace the tachometer.
Incorrectly calibrated electronic speedometer Calibrate the electronic speedometer.
Faulty speed sensor/circuit Repair the circuit or replace the speed sensor. Refer to the speed sensor DTCs.
Loose speed sensor Tighten the speed sensor retaining bracket bolt. Refer to Speed Sensor Replacement .
Degraded fluid Change the transmission fluid and filter. Refer to Automatic Transmission Fluid/Filter Replacement .
Incorrect fluid level Correct the fluid level. Refer to Transmission Fluid Checking Procedure .
Low main pressure Repair the transmission.
Intermittent conditions Inspect the wiring harnesses and connectors.
Loose or damaged speed gear Tighten the output flange bolt or replace the speed gear.
Sticking valves in the control valve body Overhaul the control valve body assembly.
Leaking pressure control solenoids Repair or replace the pressure control solenoids.