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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 16 (Automatic Transmission - 4L60-E/4L65-E/4L70-E - Service, Diagnosis & Troubleshooting) >> Road Test Procedure (M30/M32/M70) >> Manual Downshifts

Manual Downshifts

WARNING: This page is about a different variant/trim than selected.

The shift solenoid valves do not control the initial downshift for the 4-3 or the 3-2 manual downshifts. The 4-3 and the 3-2 manual downshifts are hydraulic. The 2-1 manual downshift is electronic. The solenoid states should change during or shortly after a manual downshift is selected.

Manual 4-3 Downshift

  1. Place the gear selector in the OVERDRIVE position.
  2. Accelerate the vehicle to 64-88 km/h (40-55 mph) in FOURTH gear.
  3. Release the throttle while moving the gear selector to THIRD.
  4. Verify the following:
    • The TCC releases
    • The transmission downshifts immediately to THIRD gear
    • The engine slows the vehicle

Manual 4-2 Downshift

  1. Place the gear selector in the OVERDRIVE position.
  2. Accelerate the vehicle to 64-72 km/h (40-45 mph).
  3. Release the throttle while moving the gear selector to SECOND.
  4. Verify the following:
    • The TCC releases
    • The transmission downshifts immediately to SECOND gear
    • The engine slows the vehicle

Manual 4-1 Downshift

  1. Place the gear selector in the OVERDRIVE position.
  2. Accelerate the vehicle to 48 km/h (30 mph).
  3. Release the throttle while moving the gear selector to FIRST.
  4. Verify the following:
    • The TCC releases.
    • The transmission downshifts immediately to FIRST gear.
    • The engine slows the vehicle.