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. Reinsert 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.

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 19

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 19

7

Correct the leak condition.

Did you correct the leak condition?

--

Go to Step 19

--

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 19

--

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

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.

Was the fluid contaminated?

--

Go to Step 15

Go to Step 18

15

Overhaul the transmission. Refer to Transmission Overhaul in the 4L60-E Section of the Transmission Unit Repair Manual.

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

Check and correct the fluid level as necessary.

Is the fluid level satisfactory?

--

System OK

Go to Step 1