The front axle on these trucks have a mechanical actuator that locks the front differential in. They have used vacuum, thermal and mechanical means for this. The mechanical is the most reliable. This is a common fail point on the Chevys/GMCs. It is located on the front axle next to the differential.
i have a 95 Chevy astro van.what would cause the all wheel drive to work sometimes but not all the time?
There are literally 100 different things that can cause your four-wheel-drive not to work. The most common cause is a disconnected wire on the four-wheel-drive selector switch.
When you drive over a clicking bettle.
if it is front wheel drive then you need new drive axels
A mosquito but i cant be sure because i am not a mechanic
Bad wheel bearing or defective brake pads.
The CV joint would have to be broke in 1/2 to cause the 4-wheel dr. not to work. 4-wheel drive would work BUT the front wheels would not pull.
I would say front wheel drive
Perhaps an out of balance wheel. If this is the cause it will be worse at a certain speed.
Not usually, the four wheel drive is hooked up after the transmission. If you are having problems with your transfer case it will sound like the transmission because the transfer case is bolted to the back of the transmission. The four wheel drive operates independently from the transmission. If you have a bad transfer case that would cause locking in the drive line it could cause problems, but your vehicle is designed to use the four wheel drive and typical use of your four wheel drive won't cause damage to the transmission. It would be advisable to only use it as necessary because it will decrease your fuel economy by about 20%.
it might be your drive shaft or transmission going out.