GM Service Manual Online
For 1990-2009 cars only

With this feature, engine power is sent to all four wheels all the time.

This is like four-wheel drive, but there is no separate lever or switch to engage or disengage the front axle. It is fully automatic, and adjust itself as needed for road conditions.


Object Number: 870536  Size: A3

The transfer case buttons are located to the left of the instrument panel cluster.

Use these buttons to shift into and out of four-wheel drive.

You can choose among three driving settings:

(Stabilitrak): This button is used with the Stabilitrak system and is also used to shift the transfer case into Neutral (N). For more information on using Stabilitrak see StabiliTrak® System .

(All-Wheel Drive): This setting delivers power to all four wheels as needed depending on road and driving conditions.

(4LO): This setting delivers extra torque. You may never need this setting. It sends maximum power to all four wheels. You might choose 4LO if you are driving off-road in deep sand, deep mud, deep snow and climbing or descending steep hills.

Caution: Shifting the transfer case to N (Neutral) can cause the vehicle to roll even if the transmission is in P (Park). You or someone else could be seriously injured. Be sure to set the parking brake before placing the transfer case in N (Neutral). See Parking Brake .

NEUTRAL: Shift the vehicle's transfer case to NEUTRAL only when towing your vehicle. See Recreational Vehicle Towing or Towing Your Vehicle for more information.

Indicator lights in the buttons show 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 to your dealer for service. An indicator light will flash while shifting the transfer case. It will remain illuminated when the shift is complete. If for some reason the transfer case cannot make a requested shift, it will return to the last chosen setting.

If the SERVICE 4WD message stays on, you should take your vehicle to your dealer for service. See SERVICE 4WD under Driver Information Center (DIC) .

Shifting into 4LO

To shift to the 4LO position, the ignition must be in RUN and the vehicle must be stopped or moving less than 3 mph (4.8 km/h) with the transmission in NEUTRAL (N). 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 switch. You must wait for the 4LO indicator light to stop flashing and remain illuminated before shifting your transmission in gear.

Notice: Shifting the transmission into gear before the Four-Wheel Drive Low indicator light has stopped flashing could damage the transfer case. To help avoid damaging the vehicle, always wait for the Four-Wheel Drive Low indicator light to stop flashing before shifting the transmission into gear.

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 less than 3 mph (4.8 km/h) and the transmission is in NEUTRAL (N). After 30 seconds the transfer case will return to the setting last chosen.

When in 4LO, the vehicle stability is disabled. For more information see StabiliTrak® System .

Shifting Out of 4LO

To shift from 4LO to All-Wheel Drive your vehicle must be stopped or moving less than 3 mph (4.8 km/h) with the transmission in NEUTRAL (N) and the ignition in RUN. 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 All-Wheel Drive button. You must wait for the AWD indicator light to stop flashing and remain illuminated before shifting your transmission into gear.

If the All-Wheel Drive button is pressed when your vehicle is in gear and/or moving, the All-Wheel Drive indicator light will flash for 30 seconds but will not complete the shift unless your vehicle is moving less than 3 mph (4.8 km/h) and the transmission is in NEUTRAL (N).

Shifting into NEUTRAL

To shift the transfer case to NEUTRAL do the following:

  1. Make sure the vehicle is parked so that it will not roll.
  2. Set the parking brake.
  3. Start the vehicle or turn the ignition to RUN.
  4. Connect the vehicle to the towing vehicle.
  5. Put the transmission in NEUTRAL (N).
  6. Shift the transfer case to All-Wheel Drive.
  7. Simultaneously press and hold the Stabilitrak and 4LO buttons for 10 seconds. The red NEUTRAL light will come on when the transfer case shift to NEUTRAL is complete.
  8. Shift the transmission to REVERSE (R) for one second, then shift the transmission to DRIVE (D) for one second.
  9. Turn the ignition to LOCK.
  10. Place the transmission shift lever in PARK (P).
  11. Release the parking brake prior to towing.

Shifting Out of NEUTRAL

To shift out of NEUTRAL:

  1. Set the parking brake and apply the regular brake pedal.
  2. Shift the transmission to NEUTRAL (N) and turn the ignition to RUN with the engine off.
  3. Press the button for the desired transfer case shift position (All-Wheel Drive or 4LO).
  4. After the transfer case has shifted out of NEUTRAL the red light will go out.
  5. Release the parking brake.
  6. You may start the engine and shift the transmission to the desired position.