2008 GMC Sierra 1500 Pickup Owner's Manual - Page 332

Automatic Transmission Fluid When to Check and Change Automatic Transmission Fluid It is usually not necessary to check the transmission fluid level. The only reason for fluid loss is a transmission leak or overheating the transmission. If you suspect a small leak, then use the following checking procedures to check the fluid level. However, if there is a large leak, then it may be necessary to have the vehicle towed to a dealer/ retailer service department and have it repaired before driving the vehicle further. Notice: Use of the incorrect automatic transmission fluid may damage your vehicle, and the damages may not be covered by your warranty. Always use the automatic transmission fluid listed in Recommended Fluids and Lubricants on page 6-12. Change the fluid and filter at the intervals listed in the Maintenance Schedule. See Scheduled Maintenance on page 6-4. Be sure to use the transmission fluid listed in Recommended Fluids and Lubricants on page 6-12. Too little fluid could cause the transmission to overheat. Be sure to get an accurate reading if you check your transmission fluid. Before checking the fluid level, prepare your vehicle as follows: 1. Start the engine and park your vehicle on a level surface. Keep the engine running. 2. Apply the parking brake and place the shift lever in PARK (P). 3. With your foot on the brake pedal, move the shift lever through each gear range, pausing for about three seconds in each range. Then, move the shift lever back to PARK (P). 4. Allow the engine to idle (500 - 800 rpm) for at least one minute. Slowly release the brake pedal. 5. Keep the engine running and press the Trip/Fuel button or trip odometer reset stem until TRANS TEMP (Transmission Temperature) displays on the Driver Information Center (DIC). 6. Using the TRANS TEMP reading, determine and perform the appropriate check procedure. If the TRANS TEMP reading is not within the required temperature ranges, allow the vehicle to cool, or operate the vehicle until the appropriate transmission fluid temperature is reached. How to Check Automatic Transmission Fluid Notice: Too much or too little fluid can damage your transmission. Too much can mean that some of the fluid could come out and fall on hot engine parts or exhaust system parts, starting a fire. 5-20