GM Service Manual Online
For 1990-2009 cars only

Transmission Fluid Checking Procedure (Diagnosis)

Step

Action

Value(s)

Yes

No

1

  1. Start the engine and allow the engine to idle until the transmission fluid temperature has reached the value specified.
  2. Depress the brake pedal and move the shift lever through the gear ranges, pausing a few seconds in each range. Return the shift lever to the PARK range.
  3. Raise the vehicle on a hoist. The vehicle must be level, with the engine running and the shift lever in the PARK range. Refer to Lifting and Jacking the Vehicle in General Information.
  4. Caution: The engine must be running when the transmission fluid fill plug is removed, or excessive fluid loss will occur. Transmission fluid may be hot. Since the actual fluid level is unknown, stand clear when removing the fill plug. Have a container ready to capture any lost fluid. Do not turn the engine off with the fill plug removed, as you can be injured by hot transmission fluid being expelled out of the oil fill opening.

  5. Remove the transmission plug.
  6. Important: The transmission fluid may darken with normal use and does not always indicate contamination or oxidation.

  7. Check the fluid color. If necessary, use a small screwdriver as a dipstick.

Is the fluid color clear red or light brown with no burnt odor?

At least 40°C

(At least 104°F)

Go to Step 4

Go to Step 2

2

Does the fluid have a burnt odor or a dark brown color?

--

Go to Step 8

Go to Step 3

3

Does the fluid have a cloudy or milky appearance?

--

Go to Step 7

Go to Step 8

4

Check the fluid level. The fluid level should be even with the bottom of the threaded plug hole.

Is the fluid level low?

--

Go to Step 5

Go to Step 11

5

Add DEXRON® III automatic transmission fluid in increments of 0.5L until the fluid drains from the plug hole.

Did you add more than 1.5L to the transmission?

--

Go to Step 6

Go to Step 11

6

The transmission may have a leak. Refer to Fluid Leak Diagnosis .

Was a transmission fluid leak found?

--

Go to Step 9

Go to Step 11

7

The transmission fluid is contaminated with engine coolant. Repair or replace the transmission cooler in the radiator.

Is the transmission cooler repair complete?

--

Go to Step 9

--

8

  1. Drain the fluid by removing the bottom pan.
  2. Important: A very small amount of material in the bottom of the bottom pan is a normal condition.

  3. Check the bottom pan for any excessive debris.

Was excessive debris found?

--

Go to Step 9

Go to Step 10

9

  1. Repair the transmission if required (in some cases, overhaul may be required).
  2. Flush the transmission oil cooler and pipes and check flow. Refer to Transmission Fluid Cooler Flushing and Flow Test .
  3. Add enough DEXRON® III automatic transmission fluid to bring the fluid level to the bottom of the threaded plug hole.
  4. Start the engine and allow the engine to idle until the transmission fluid temperature has reached the value specified.
  5. Depress the brake pedal and move the shift lever through the gear ranges, pausing a few seconds in each range. Return the shift lever to the PARK range.
  6. Raise the vehicle on a hoist. The vehicle must be level, with the engine running and the shift lever in the PARK range. Refer to Lifting and Jacking the Vehicle in General Information.
  7. Caution: The engine must be running when the transmission fluid fill plug is removed, or excessive fluid loss will occur. Transmission fluid may be hot. Since the actual fluid level is unknown, stand clear when removing the fill plug. Have a container ready to capture any lost fluid. Do not turn the engine off with the fill plug removed, as you can be injured by hot transmission fluid being expelled out of the oil fill opening.

  8. Remove the transmission plug.
  9. If needed, add DEXRON® III automatic transmission fluid in increments of 0.5L until the fluid drains from the threaded plug hole.
  10. Allow fluid to finish draining out of the plug hole. Install the plug and tighten to specified value.
  11. Wipe any excess fluid from the transmission with a rag or shop towel.

Is the repair complete?

At least 40°C

(At least 104°F)

12 N·m

(9 lb ft)

Go to Functional Test

--

10

  1. Change the fluid and the fluid filter. Refer to Automatic Transmission Fluid Filter and Seal Replacement .
  2. Start the engine and allow the engine to idle until the transmission fluid temperature has reached the value specified.
  3. Depress the brake pedal and move the shift lever through the gear ranges, pausing a few seconds in each range. Return the shift lever to the PARK range.
  4. Raise the vehicle on a hoist. The vehicle must be level with the engine running and the shift lever in the PARK range. Refer to Lifting and Jacking the Vehicle in General Information.
  5. Caution: The engine must be running when the transmission fluid fill plug is removed, or excessive fluid loss will occur. Transmission fluid may be hot. Since the actual fluid level is unknown, stand clear when removing the fill plug. Have a container ready to capture any lost fluid. Do not turn the engine off with the fill plug removed, as you can be injured by hot transmission fluid being expelled out of the oil fill opening.

  6. Remove the transmission plug.
  7. If needed, add DEXRON® III automatic transmission fluid in increments of 0.5L until the fluid drains from the threaded plug hole.
  8. Allow fluid to finish draining out of the plug hole. Install the plug and tighten to specified value.
  9. Wipe any excess fluid from the transmission with a rag or shop towel.

Is the repair complete?

At least 40°C

(At least 104°F)

12 N·m

(9 lb ft)

Go to Functional Test

--

11

  1. Allow fluid to finish draining out of the plug hole. Install the plug and tighten to specified value.
  2. Wipe any excess fluid from the transmission with a rag or shop towel.

Is the repair complete?

12 N·m

(9 lb ft)

Go to Functional Test

--