Automatic Transmission - 4L80-E/4L85-E (Service & Replacement): Maintenance GMC Savana H2500

Transmission Fluid Pressure (TFP) Manual Valve Position Switch Logic

Transmission Fluid Pressure (TFP) Manual Valve Position Switch Logic

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 852

Scheme 853

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 854

Cooler Flow Check and Flushing Steps

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

Tools Required

1. J 35944-A Transmission Oil Cooler and Line Flusher
2. J 35944-22 Transmission Oil Cooler Flushing Fluid
3. J 35944-200 Cooler Flushing Adapter
4. Measuring cup
5. Funnel
6. Water supply - hot water recommended
7. Water hose, at least 16 mm (5/8 in) ID
8. Shop air supply with water/oil filters, regulator and pressure gage
9. Air chuck with clip, if available
10. Oil drain container
11. Pail with lid - 19 L (5 gallon)
12. Eye protection
13. Rubber gloves

1. Machine Set-up
2. Determine Minimum Flow Rate
3. Back Flush
4. Forward Flush
5. Flow Test
6. Code Recording Procedure
7. Clean-up

Tools Required

1. J 35944-200 Cooler Flushing Adapter
2. J 45096 Transmission Oil Cooling System Flush and Flow Test Tool
3. Shop air supply with water/oil filters, regulator and pressure gage - minimum 90 psi
4. Eye protection
5. Rubber gloves

Scheme 855

Scheme 856

Scheme 857

1. Verify that the main power switch (1) is in the OFF position.
2. Place the main function switch (2) in the IDLE position.
3. Connect J 45096 to the vehicle 12V DC power source by connecting the red battery clip to the positive, +, battery post on the vehicle and connect the negative lead to a known good chassis ground.
4. Turn the main power switch to the ON position. CAUTION: Do not overfill the supply vessel. Damage to the unit may result. To verify the fluid level, view the LCD screen display while filling the unit to ensure that the fluid level does not exceed 32 quarts (30 liters).
5. Fill the supply tank with DEXRON®III/Mercon®, or equivalent, through the fill port.
6. Reinstall and tighten the fill cap.
7. Connect a shop air supply hose to the quick-disconnect on the rear panel marked SUPPLY AIR.

Scheme 858

Scheme 859

1. From the machine display, identify the temperature of the automatic transmission fluid that is stored in the supply vessel of J 45096 .
2. Determine whether the transmission oil cooler is steel or aluminum by using a magnet (1) at the cooler flange (2) at the radiator.
3. Refer to the table below. Using the temperature from step 1, locate on either the Steel MINIMUM Flow Rate table or the Aluminum MINIMUM Flow Rate table the minimum flow rate in gallons per minutes (GPM). Record the minimum flow rate in GPMs and the supply fluid temperature for further reference. Example: Fluid temperature: 75 °F Cooler type: Steel The MINIMUM flow rate for this example would be 0.8 GPM.
4. Inspect transmission oil cooler lines for damage or kinks that could cause restricted oil flow. Repair as needed and refer to the appropriate GM service manual procedures. Minimum Flow Rate In Gallons Per Minute (GPM) Temperature Range Steel Aluminum 65 to 66°F 0.6 gpm 0.5 gpm 67 to 70°F 0.7 gpm 0.6 gpm 71 to 75°F 0.8 gpm 0.7 gpm 76 to 80°F 0.9 gpm 0.8 gpm 81 to 84°F 1.0 gpm 0.9 gpm 85 to 89°F 1.1 gpm 1.0 gpm 90 to 94°F 1.2 gpm 1.1 gpm 95 to 98°F 1.3 gpm 1.2 gpm 99 to 103°F 1.4 gpm 1.3 gpm 104 to 108°F 1.5 gpm 1.4 gpm 109 to 112°F 1.6 gpm 1.5 gpm 113 to 117°F 1.7 gpm 1.6 gpm 118 to 120°F 1.8 gpm 1.7 gpm

Scheme 860

Scheme 861

Scheme 862

1. Connect the J 45096 adapters (1) to the vehicle's transmission oil cooler supply and return lines at the transmission. May require the use of J 35944-200 cooler flushing adapter.
2. Connect the black supply hose (1) to the return line, rear connector of the transmission, and the clear waste hose (2) to the feed line, front connector of the transmission, to the vehicle cooler lines. This is the reverse flow - backflush direction.
3. Turn the main function switch to the FLUSH position. Allow the machine to operate for 30 seconds.
4. Turn the main function switch to the IDLE position and allow the supply vessel pressure to dissipate.

Scheme 863

1. Disconnect the supply and waste hoses from the vehicle cooler lines. Reverse the supply and waste hoses to provide a normal flow direction.
2. Turn the main function switch to the FLUSH position and allow machine to operate for 30 seconds.

Inadequate Lubrication at Low Line or Heavy Loads

Inadequate Lubrication At Low Line Or Heavy Loads

Inadequate Lubrication

Inadequate Lubrication