The Chevrolet Avalanche four-door pickup truck comes available with either two- or four-wheel drive. Four-wheel drive Avalanches have a transfer case added to the transmission in order to power not only the back wheels but also the front wheels when needed. All Avalanches, whether two- or four-wheel drive, come with automatic transmissions as standard equipment. There is no manual transmission option available for the Avalanche.
The Chevrolet Avalanche comes with a five-speed automatic transmission with an overdrive sixth gear. The Avalanche also comes with a traction control system that adjusts power between the drive wheels to maintain optimum contact with the road. The 2001 through 2003 models had only five-speed transmissions with overdrive, but the linkage and transmission/engine assembly are the same for all models.
The most common problem with Avalanche automatic transmissions is fluid loss or contamination. Transmission fluid both lubricates and cools the transmission case. When the fluid level is low, the ability to carry away heat is reduced. Contamination in the fluid can lead to poor gear lubrication.
Four-wheel drive Chevy Avalanches have a transfer case located forward of the transmission to transfer power on demand to the front wheels. The transfer case is also sealed and filled with fluid that must be kept at specified levels. Transmission problems related to the Avalanche's transfer case can be detected if, when selecting four-wheel drive, there is no appreciable gain in traction from the front wheels. Also, transfer case problems are noticeable when there is an acrid burning smell when engaging the four-wheel drive. Although the chance of fire is very slight, the smell indicates the transfer case fluid is being overheated by a poorly performing gear or shaft. When this happens, the problem will need immediate attention.
Just like a standard gearshift transmission, all automatic transmissions also have a clutch and clutch plates. If there is a noticeable lag in performance during acceleration, this could indicate a clutch problem. In this case, the Avalanche's automatic transmission is not able to seamlessly change gears. The only possible repair for clutch problems is replacement of the failed or failing plate or linkage.
Individual gears in the Avalanche's transmission case can fail. When this happens, you'll notice grinding sounds, poor gear changes and even a slight burning smell. This is because the gears are not spinning correctly and are overheating the transmission. Although a transmission rebuild can be expensive, the only repair option is to pull the failed gear and associated shafts and replace them with new components.
