GM Service Manual Online
For 1990-2009 cars only

If your vehicle has four-wheel drive, you can send your engine's driving power to all four wheels for extra traction. To get the most satisfaction out of four-wheel drive, you must be familiar with its operation. Read the part that follows before using four-wheel drive. See Off-Road Recovery .

You should use two-wheel high (2HI) for most normal driving conditions.

Notice: Driving on clean, dry pavement in four-wheel drive for an extended period of time can cause premature wear on the vehicle's powertrain. Do not drive on clean, dry pavement in Four-Wheel Drive for extended periods of time.

Electronic Transfer Case


Object Number: 809370  Size: A2

If your four-wheel drive vehicle has the electronic transfer case, the transfer case buttons are to the right of the steering wheel on the instrument panel.

Use these buttons to shift into and out of four-wheel-drive. You can choose among three driving settings:

2HI (Two-Wheel Drive High): This setting is for driving in most street and highway situations. Your front axle is not engaged in two-wheel drive. When this light is turned on, it is about one-half as bright as the others.

4HI (Four-Wheel Drive High): This setting engages your front axle to help drive your vehicle. Use 4HI when you need extra traction, such as on snowy or icy roads, or in most off-road situations.

4LO (Four-Wheel Drive Low): You may never need 4LO. This setting also engages your front axle to give you extra traction. It sends the maximum power to all four wheels. You might choose 4LO if you were driving off-road in sand, mud or deep snow and climbing or descending steep hills. Indicator lights in the buttons show you which setting you are in. The indicator lights will come on briefly when you turn on the ignition and one will stay on. If the lights do not come on, you should take your vehicle in for service. An indicator light will flash while shifting. It will remain illuminated when the shift is completed.

Shifting from 2HI to 4HI

Press and release the 4HI button. This can be done at any speed, and the front axle will lock automatically.

Shifting from 4HI to 2HI

Press and release the 2HI button. This can be done at any speed, and the front axle will unlock automatically.

Shifting from 2HI or 4HI to 4LO

To shift from 2HI or 4HI to 4LO, the vehicle must be stopped or moving less than 3 mph (4.8 km/h) with the transmission in NEUTRAL (N) in vehicles equipped with an automatic transmission or the clutch pedal engaged in vehicles equipped with a manual transmission. The preferred method for shifting into 4LO is to have your vehicle moving 1 to 2 mph (1.6 to 3.2 km/h). Press and release the 4LO button. You must wait for the 4LO indicator light to stop flashing and remain illuminated before shifting your transmission into gear or releasing the clutch pedal.

If the 4LO button is pressed when your vehicle is in gear and/or moving, the 4LO indicator light will flash for 30 seconds and not complete the shift unless your vehicle is moving slower than 3 mph (4.8 km/h) and the transmission is in NEUTRAL (N) or the clutch pedal engaged.

On automatic transmission equipped vehicles, if your transfer case does not shift into 4LO, your transmission indicator switch may require adjustment. With your transmission in NEUTRAL (N), press and release the 4LO button. While the 4LO indicator light is flashing, shift your transmission into PARK (P). Wait until the 4LO indicator light remains illuminated before shifting your transmission into gear. This will get you into 4LO, but you should take your vehicle in for service to restore normal operation.

Shifting from 4LO to 4HI or 2HI

To shift from 4LO to 4HI or 2HI, your vehicle must be stopped or moving less than 3 mph (4.8 km/h) with the transmission in NEUTRAL (N) or the clutch pedal engaged. The preferred method for shifting out of 4LO is to have your vehicle moving 1 to 2 mph (1.6 to 3.2 km/h). Press and release the 4HI button. You must wait for the 4HI indicator light to stop flashing and remain illuminated before shifting your transmission into gear or releasing the clutch pedal.

If the 4HI button is pressed when your vehicle is in gear and/or moving, the 4HI indicator light will flash for 30 seconds but not complete the shift unless the vehicle is moving slower than 3 mph (4.8 km/h) and the transmission is in NEUTRAL (N) or the clutch pedal engaged.

On automatic transmission equipped vehicles, if your transfer case does not shift into 4HI, your transmission indicator switch may require adjustment. With your transmission in NEUTRAL (N), press and release the 4HI button. While the 4HI indicator light is flashing, shift your transmission into PARK (P). Wait until the 4HI indicator light remains illuminated before shifting your transmission into gear. This will get you into 4HI, but you should take your vehicle in for service to restore normal operation.