Transmission Fluid Checking Procedure
- 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).
- Park the vehicle on a level surface.
- With your foot on the brake, move the shift lever through each gear range. Pause for about 3 seconds in each range, ending in PARK.
- Apply the parking brake and let the engine idle for 3 minutes.
- Remove the transmission fluid level indicator. Wipe the indicator clean. Insert the indicator. Give the indicator a full twist in order to close.
- Wait 3 seconds and remove the indicator.
- Read both sides of the indicator. The fluid must be within the hot cross-hatched area using the lowest level reading.
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Check the fluid color. Is the fluid red in color? | Go to Step 5 | Go to Step 2 |
| 2 | Is the fluid a non-transparent pink in color? | Go to Step 14 | Go to Step 3 |
| 3 | IMPORTANT: Fluid may turn a dark brown in color from normal use. This does not always indicate an oxidation or a contamination issue. Is the fluid a light brown in color? | Go to Step 5 | Go to Step 4 |
| 4 | Is the fluid black in color and or have a "burnt" smell? | Go to Step 14 | Go to Step 5 |
| 5 | Does the fluid appear as a solid "liquid" and not "foamy" or full of bubbles on level indicator? | Go to Step 6 | Go to Step 6 |
| 6 | Check the fluid level. Proper level should be in middle of the "X" pattern, on level indicator. Is the level OK? | Go to Step 19 | Go to Step 7 |
| 7 | Is the fluid level high on indicator? | Go to Step 12 | Go to Step 8 |
| 8 | Is the fluid level low on indicator? | Go to Step 9 | Go to Step 4 |
| 9 | Check for any external leak or leaks. Refer to Fluid Leak Diagnosis . Did you find an external leak or leaks? | Go to Step 10 | Go to Step 11 |
| 10 | Correct leak or leaks as needed. Are any leak or leaks still present? | Go to Step 9 | Go to Step 11 |
| 11 | Add fluid until level is in middle of "X" pattern on the level indicator. Is the level OK? | Go to Step 19 | Go to Step 6 |
| 12 | Drain fluid until level is in middle of "X" pattern on the level indicator. Is level OK? | Go to Step 19 | Go to Step 6 |
| 13 | Replace oil cooler and flush lines. Is the replacement complete? | Go to Step 15 | |
| 14 | IMPORTANT: A small amount of "friction" material in pan bottom is a "normal" condition, but large pieces and or metal particles will require complete transmission overhaul. Drain fluid and remove oil pan to inspect.Is there sign or signs of internal component damage noted in bottom of transmission oil pan? | Go to Step 16 | Go to Step 13 |
| 15 | Replace the filter and fluid. Refer to Automatic Transmission Fluid/Filter Replacement . Is the replacement complete? | Go to Step 6 | |
| 16 | Flush oil cooler and lines. Refer to Automatic Transmission Oil Cooler Flushing and Flow Test (J 45096) Automatic Transmission Oil Cooler Flushing and Flow Test (J 35944-A) . Is the Automatic Transmission Oil Cooler Flushing and Flow Test complete? | Go to Step 17 | |
| 17 | Overhaul the transmission. Is the Transmission Overhaul Procedure complete? | Go to Step 18 | |
| 18 | Add new fluid. Is the procedure complete? | Go to Step 6 | |
| 19 | Check the fluid level and correct as necessary. Is the fluid level satisfactory? | Go to Step 20 | |
| 20 | If equipped, reset the oil life monitor to 100 percent. Are all of the reset procedures complete? | System OK | Go to Step 1 |
| IMPORTANT |
|---|
| Fluid may turn a dark brown in color from normal use. This does not always indicate an oxidation or a contamination issue. |
| IMPORTANT |
|---|
| A small amount of "friction" material in pan bottom is a "normal" condition, but large pieces and or metal particles will require complete transmission overhaul. |
Transmission Fluid Checking Procedure
Possible Points of Fluid Leaks
Transmission Oil Pan
- Incorrectly tightened oil pan bolts
- Improperly installed or damaged oil pan gasket
- Damaged oil pan or mounting face
- Incorrect oil pan gasket
Case Leak
- Damaged or missing fill tube seal
- Mislocated fill tube bracket
- Damaged vehicle speed sensor seal
- Damaged manual shaft seal
- Loose or damaged oil cooler connector fittings
- Worn or damaged propeller shaft oil seal
- Loose line pressure pipe plug
- Porous casting warped torque converter housing
Leak at the Torque Converter End
- Converter leak in the weld area
- Converter seal lip cut. Check the converter hub for damage
- Converter seal bushing moved forward and damaged
- Converter seal garter spring missing from the seal
- Porous casting of the transmission case or the oil pump
Leak at the Vent Pipe or the Fluid Fill Tube
- Overfilled system
- Water or coolant in the fluid. The fluid will appear milky
- Transmission case porous
- Incorrect fluid level indicator
- Plugged vent
- Drain-back holes plugged
- Mispositioned oil pump to case gasket, if equipped
Scheme 462
| Callout | Component Name |
|---|---|
| 1 | Wiring Harness Pass-Through Connector O-ring Seal |
| 2 | Transmission Vent Assembly |
| 3 | Converter Housing to Case Joint (Pump to Case Oil Seal) |
| 4 | Line Pressure Plug |
| 5 | Case Extension to Case Seal |
| 6 | Manual Shaft Seal |
| 7 | Case Extension Oil Seal Assembly |
| 8 | Torque Converter Assembly |
| 9 | Pump to Case Oil Seal |
| 10 | Pump Oil Seal Assembly |
| 11 | Internal Transmission Speed Sensor to Case O-ring Seal - Some Models |
| 12 | 2-4 Servo Cover O-ring Seal |
| 13 | Oil Fill Tube Seal |
| 14 | Oil Cooler Pipe Connectors |
| 15 | Transmission Case |
| 16 | Transmission Oil Pan Gasket |
Cooler Flow Check and Flushing Steps
- Machine Set-up
- Determine Minimum Flow Rate
- Back Flush
- Forward Flush
- Flow Test
- Code Recording Procedure
- Clean-up
Tools Required
- J 35944-200 Cooler Flushing Adapter
- J 45096 Transmission Oil Cooling System Flush and Flow Test Tool
- Shop air supply with water/oil filters, regulator and pressure gage - minimum 90 psi
- Eye protection
- Rubber gloves
Scheme 463
- Verify that the main power switch (1) is in the OFF position.
- Place the main function switch (2) in the IDLE position.
- Connect J 45096 to the vehicle 12-volt 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.
- Turn the main power switch to the ON position.
- Fill the supply tank with Dexron®III/Mercon®, or equivalent, through the fill port.
- Install and tighten the fill cap.
- Connect a shop air supply hose to the quick-disconnect on the rear panel marked SUPPLY AIR.
Scheme 464
- From the machine display, identify the temperature of the automatic transmission fluid that is stored in the supply vessel of J 45096 .
- Determine whether the transmission oil cooler is steel or aluminum by using a magnet (1) at the cooler flange (2) at the radiator.
- 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: 24°C (75°F) Cooler type: Steel The MINIMUM flow rate for this example would be 0.8 GPM.
- 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.
| Temperature Range | Steel | Aluminum |
|---|---|---|
| 65-66°F | 0.6 gpm | 0.5 gpm |
| 67-70°F | 0.7 gpm | 0.6 gpm |
| 71-75°F | 0.8 gpm | 0.7 gpm |
| 76-80°F | 0.9 gpm | 0.8 gpm |
| 81-84°F | 1.0 gpm | 0.9 gpm |
| 85-89°F | 1.1 gpm | 1.0 gpm |
| 90-94°F | 1.2 gpm | 1.1 gpm |
| 95-98°F | 1.3 gpm | 1.2 gpm |
| 99-103°F | 1.4 gpm | 1.3 gpm |
| 104-108°F | 1.5 gpm | 1.4 gpm |
| 109-112°F | 1.6 gpm | 1.5 gpm |
| 113-117°F | 1.7 gpm | 1.6 gpm |
| 118-120°F | 1.8 gpm | 1.7 gpm |
Minimum Flow Rate in Gallons Per Minute (GPM)
Scheme 465
Scheme 466
- Connect the J 45096 adapters (1) to the vehicle's transmission oil cooler supply and return lines at the transmission, may require J 35944-200 .
- Connect the black supply hose (1) to the return line, top connector of the transmission, and the clear waste hose (2) to the feed line, bottom connector of the transmission, to the vehicle cooler lines. This is the reverse flow-backflush direction.
- Turn the main function switch to the FLUSH position. Allow the machine to operate for 30 seconds.
- Turn the main function switch to the IDLE position and allow the supply vessel pressure to dissipate.
Scheme 467
- Disconnect the supply and waste hoses from the vehicle cooler lines. Reverse the supply and waste hoses to provide a normal flow direction.
- Turn the main function switch to the FLUSH position and allow the machine to operate for 30 seconds.
Forward Flush
- Disconnect both hoses (1 and 2) from the oil cooler pipes and connect them to the opposite oil cooler pipe. This will allow the oil cooler and pipes to be flushed in the normal flow direction.
- Repeat Step 6 and 7 of the Back Flush.
- Release the trigger (1) of the J 35944-A and allow water only to rinse the oil cooler and pipes for 1 minute.
- Turn the J 35944-A water supply valve (3) to the OFF position and turn OFF the water supply at the faucet.
- Attach the shop air supply to the flushing system feed air valve (2) on the J 35944-A and blow out the water from the oil cooler and pipes. Continue, until no water comes out of the discharge hose.
Secondary Fluid Pump Overheats (M33 Only)
| Checks | Causes |
|---|---|
| Inspect transmission fluid level. Refer to Transmission Fluid Checking Procedure . Transmission bottom pan damage. | Low or high fluid level. |
| Restricted Secondary Fluid Pump filter or pump inlet. Pump motor high current draw. Worn secondary fluid pump motor bearings or worn pump gears. | Secondary Fluid Pump. |
Secondary Fluid Pump Overheats (M33 Only)
High or Low Secondary Fluid Pump Pressure (M33 Only)
| Checks | Causes |
|---|---|
| Inspect transmission fluid level. Refer to Transmission Fluid Checking Procedure . | Incorrect fluid level. |
| Restricted Secondary Fluid Pump filter. Pump motor overheating. Worn or leaking pump. Valve body check valve stuck or sticking. Secondary Fluid Pump relief valve stuck open. Oil circuit restriction. | Incorrect pump volume. |
High or Low Secondary Fluid Pump Pressure (M33 Only)
No Secondary Fluid Pump Pressure (M33 Only)
| Checks | Causes |
|---|---|
| Secondary Fluid Pump Diagnostic trouble code (DTC) set. Refer to DTC P2796 (M33 Only) and DTC P2797 (M33 Only) . Poor Secondary Fluid Pump electrical connection. Loose Secondary Fluid Pump. Secondary Fluid Pump leaking. Secondary Fluid Pump seized or pump damaged. | Secondary Fluid Pump. |
No Secondary Fluid Pump Pressure (M33 Only)
Whine Noise Varying with RPM or Fluid Pressure
| Checks | Action |
|---|---|
| DEFINITION: In all ranges, a whine which may be sensitive to RPM load, or which ceases when the TCC engages, or which is sensitive to the oil pressure | |
| Torque Converter (1) | Verify that the noise is internal to the torque converter by placing your left foot on the brake with the gear or selector in Drive. Momentarily stall the engine. Torque Converter noise increases under load. |
| Oil Pump System | Verify that the noise is internal to the oil pump during a preliminary oil pressure check. An increase in line pressure will vary an oil pump noise. |
Whine Noise Varying with RPM or Fluid Pressure
Secondary Fluid Pump Noise (M33 Only)
| Checks | Causes |
|---|---|
| Inspect transmission fluid level. Refer to Transmission Fluid Checking Procedure . Transmission bottom pan damage. | Incorrect fluid level. |
| Secondary Fluid Pump contracting oil pan due to damage. Secondary Fluid Pump is loose. Secondary Fluid Pump overheating. Pump motor high current draw. High transmission fluid temperatures. | Secondary Fluid Pump. |
Secondary Fluid Pump Noise (M33 Only)