On both selective four wheel drive and full time four wheel drive vehicles, the transfer case needs to be shifted between two wheel drive and four wheel drive modes. On push button models, this is achieved by an electronic motor referred to as an encoder motor. The front axle actuator is an electronic motor that locks the front axle to gather for four wheel drive operation. Both of these are controlled by a computer called the Transfer Case Control Module or TCCM.
In addition to providing four wheel drive and two wheel drive, the transfer case also has the capability to provide additional gear reduction to help in severe conditions. This function is referred to as low range four wheel drive.
Now that you know more about what happens when you push the four wheel drive button, you may ask yourself what it takes to ensure it is working when you need it. Both front and rear axles simply need the fluid changed and inspected for leaks or excessive play. The transfer case also needs its fluid changed, inspected for leaks and a functional check of the shifting mechanism. Front and rear drive shafts should have the splines and joints lubed and inspected for free range of motion.
Everett’s service staff will be glad to service your four wheel drive system; however, we are committed to more than just service. Our service staff not only has the knowledge to fix your vehicle, we also want to help you understand your vehicle. That’s the Everett Advantage and that’s what makes us better.
David Gibbs
Certified Service Technician
Everett Chevrolet Buick GMC