Automatic Transmission - 4L80-E - Service & Replacement: Maintenance Chevrolet Silverado 1500 HD

Transmission Fluid Checking Procedure

1. Start the engine and operate the vehicle for 15 minutes or until the transmission fluid reaches an operating temperature of 82-93°C (180-200°F).
2. Park the vehicle on a level surface.
3. With your foot on the brake, move the shift lever through each gear range. Pause for about three seconds in each range, ending in Park.
4. Apply the parking brake and let the engine idle for 3 minutes.
5. Remove the transmission fluid level indicator. Wipe the indicator clean. Insert the indicator. Give the indicator a full twist in order to close.
6. Wait 3 seconds and remove the indicator.
7. Read both sides of the indicator. The fluid must be within the hot cross-hatched area using the lowest level reading.

Scheme 1175

Scheme 1176

Leak at the Vent Pipe or the Fluid Fill Tube

1. Overfilled system
2. Water or coolant in the fluid. The fluid will appear milky
3. Transmission case porous
4. Incorrect fluid level indicator
5. Plugged vent
6. Drain-back holes plugged
7. Mispositioned oil pump to case gasket, if equipped

Scheme 1177

Cooler Flow Check and Flushing Steps

1. Tools Required
2. Preparation
3. Back Flush
4. Forward Flush
5. Flow Check
6. Clean-up