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.
  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 three 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 three 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.

Step

Action

Value(s)

Yes

No

DEFINITION: Diagnose transmission fluid conditions by color.

1

Check the fluid color.

Is the fluid color red?

--

Go to Step 2

Go to Step 11

2

Is the fluid level satisfactory?

--

System OK

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

The 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 .

Were any leaks found?

--

Go to Step 7

Go to Step 20

7

Correct the leak condition.

Was the leak condition corrected?

--

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. Refer to Automatic Transmission Fluid and Filter Replacement.

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.

Was the fluid drained?

--

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

Important: 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.

Drain the fluid to determine if the fluid is contaminated.

Is the fluid contaminated?

--

Go to Step 15

Go to Step 18

15

Replace the transmission. Refer to Transmission Replacement.

Is the replacement complete?

--

Go to Step 16

--

16

Clear TRANS ADAPT.

Are the reset procedures complete?

--

Go to Step 17

--

17

Add new fluid.

Is the procedure complete?

--

Go to Step 20

--

18

Change the fluid and the filter.

Refer to Automatic Transmission Fluid and Filter Replacement.

Is this procedure complete?

--

Go to Step 19

--

19

Are the reset procedures complete?

--

Go to Step 20

--

20

Is the fluid level satisfactory?

--

System OK

Go to Step 1