GM Service Manual Online
For 1990-2009 cars only
  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. Apply the parking brake and block the wheels.
  3. While the engine is idling and with your foot on the brake pedal, move the shift lever through each gear range, ending in Park.
  4. Check the fluid level, color and condition (transmission fluid conditions are diagnosed by color). The fluid will be higher on the fluid level indicator when the transmission is cold. Conversely, the fluid level will drop when it is checked at operating temperature.
  5. If it is necessary to add fluid, DEXRON®-III Automatic Transmission Fluid is preferred. DEXRON®-IIE is an acceptable substitute.

Transmission Fluid Checking Procedure

Step

Action

Value(s)

Yes

No

1

Check the fluid color.

Is the fluid color red?

--

Go to Step 2

Go to Step 11

2

Is the fluid level satisfactory?

--

Go to Step 20

Go to Step 3

3

Check the fluid.

Is the fluid foamy?

--

Go to Step 8

Go to Step 4

4

Check the fluid level. The proper fluid level should be in the middle of the X-hatch.

Is the level high?

--

Go to Step 9

Go to Step 5

5

Fluid will be low.

Add fluid to the proper fluid level.

Is the fluid level satisfactory?

--

Go to Step 6

--

6

Check for external leaks. Refer to Fluid Leak Diagnosis.

Did you find any leaks?

--

Go to Step 7

Go to Step 20

7

Correct the leak condition.

Did you correct the leak condition?

--

Go to Step 20

--

8

Is the fluid level too high?

--

Go to Step 9

Go to Step 10

9

Remove excess fluid to the proper fluid level.

Is the fluid level satisfactory?

--

Go to Step 20

--

10

  1. Check for contaminants in the fluid.
  2. Drain the fluid to determine the source of the contamination.

Did you drain the fluid?

--

Go to Step 15

--

11

Is the fluid color non-transparent pink?

--

Go to Step 12

Go to Step 13

12

Replace the cooler.

Is the replacement complete?

--

Go to Step 15

--

13

Important: Transmission fluid may turn dark with normal use. This does not always indicate oxidation or contamination.

The fluid color should be light brown.

Is the fluid color light brown?

--

Go to Step 14

--

14

Drain the fluid to determine if the fluid is contaminated.

A very small amount of material in the bottom pan is a normal condition, but large pieces of metal or other material in the bottom pan require a transmission overhaul.

Was the fluid contaminated?

--

Go to Step 15

Go to Step 18

15

Overhaul the transmission. Refer to Unit Repair.

Is the overhaul complete?

--

Go to Step 16

--

16

Flush the cooler.

Has the cooler been flushed?

--

Go to Step 17

--

17

Add new fluid.

Is the procedure complete?

--

Go to Step 19

--

18

Change the fluid and the filter.

Is this procedure complete?

--

Go to Step 19

--

19

Is the fluid level satisfactory? If not, correct as necessary.

--

Go to Step 20

--

20

Perform the Functional Test Procedure.

Is the Functional Test completed?

--

System OK

--