GM Service Manual Online
For 1990-2009 cars only

The transmission fluid checking procedure is an important part of any mechanical/hydraulic system diagnosis. The transmission fluid condition can be a reliable indicator of the presence of problems within the transmission.

Step

Action

Value(s)

Yes

No

1

Was the Powertrain or Transmission On-Board Diagnostic (OBD) System Check performed?

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Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Warm the transmission to the operating temperature by driving the vehicle the specified distance, or by running the engine until the Transmission Fluid Temperature has reached the value specified.
  2. Raise the vehicle on a hoist. The vehicle must be level when removing the transmission fluid fill plug. If a hoist is unavailable, the vehicle must be lifted at both ends and suitably supported.
  3. Caution: Do not turn the engine off with the transmission fluid fill plug removed. The engine must be running when the fill plug is removed, or excessive fluid loss will occur. Have a container ready to capture any lost fluid. Stand clear when removing the fill plug since the actual fluid level is unknown. Transmission fluid may be hot. Wear gloves and safety glasses when removing the transmission fluid fill plug in order to prevent personal injury.

  4. Start the engine.
  5. With the engine running and the transmission at the normal operating temperature, remove the transmission fluid fill plug.
  6. Check the fluid color. If necessary, use a small screwdriver as a dip stick.

Important: The transmission fluid may darken with normal use and does not always indicate contamination or oxidation.

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

15 miles (24 km) 113-185°F (45-85°C)

Go to Step 5

Go to Step 3

3

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

--

Go to Step 8

Go to Step 4

4

Does the fluid have a cloudy or milky appearance?

--

Go to Step 7

Go to Step 8

5

Check the fluid level. The fluid level should be even with the bottom of the threaded opening in the transmission pan.

Is the fluid level low?

--

Go to Step 6

Return to Functional Test

6

  1. With the engine running, add only enough DEXTRON®-III Automatic Transmission Fluid to bring the fluid level to the bottom of the threaded opening in the transmission pan.
  2. Check the transmission for any external leaks in the following areas:
  3. • The transmission pan and gasket
    • The transmission lines
    • The case cover bolts

Refer to Fluid Leak Diagnosis.

Is the repair complete?

--

Return to Functional Test

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7

Replace the transmission cooler.

Is the repair complete?

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Go to Step 9

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8

Important: A very small amount of material in the bottom of the pan is a normal condition.

Drain the fluid. Check the bottom of the pan for any excessive debris.

Was a problem found?

--

Go to Step 9

Go to Step 10

9

  1. Overhaul the transmission if required.
  2. Flush transmission cooler and lines.
  3. Add enough DEXTRON®-III Automatic Transmission Fluid to bring the fluid level to the bottom of the threaded opening in the transmission pan.
  4. Start the engine.
  5. Continue to add fluid as the torque converter and other components fill with fluid. Allow the transmission to reach the normal operating temperature.
  6. Add enough DEXTRON®-III Automatic Transmission Fluid in order to bring the fluid level to the bottom of the threaded opening in the transmission pan.

Is the repair complete?

--

Return to Functional Test

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10

  1. Change the fluid and the fluid filter.
  2. Add enough DEXTRON®-III Automatic Transmission Fluid in order to bring the fluid level to the bottom of the threaded opening in the transmission pan.
  3. Start the engine.
  4. Continue to add the fluid as the torque converter and the other components fill with fluid. Allow the transmission to reach normal operating temperature.
  5. Add enough DEXTRON-III Automatic Transmission Fluid in order to bring the fluid level to the bottom of the threaded opening in the transmission pan.

Is the repair complete?

--

Return to Functional Test

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