How to Test a Four-wheel Drive

by Thomas Springer
itstillruns article image
military truck image by Ian Danbury from

A four-wheel drive vehicle can get you safely where you need to go though rain, mud or snow. Before testing the four-wheel drive, check as you would on any vehicle that the brakes are working, the tires have the recommended pressure and the engine fluids are at the correct levels. Search for rust around the doors and underneath the vehicle. Excessive rust will give you an indication of how often the previous owner used the vehicle off-road and how well he maintained it.

Step 1

itstillruns article image

Locate the four-wheel drive high button on the dash. It might also be a second shifter to your right. It will be marked 4Hi.

Step 2

itstillruns article image

Drive the vehicle as normal and press the button or shift into 4Hi. You can engage 4Hi at any time and speed. You might hear a slight "clunking" sound as the transfer case underneath and to the front of the driver side engages the four-wheel drive system; this is normal. However, any continuous grinding noises are a warning of damage to the four-wheel drive system.

Step 3

Turn the vehicle to the left and right while moving. On a loose or wet surface, it should turn normally. If you are on dry pavement, you may feel the tires grab a little as if they were catching against the ground; this is fine. However, popping noises from any wheel may be a sign of damage to the constant velocity joints or boots. The CV joints and boots are the mechanisms that allow a wheel to turn.

Step 4

Locate the four-wheel drive low button on the dash or shifter. It will be marked 4Lo.

Step 5

Stop the vehicle. You cannot engage the 4Lo until you are stationary.

Step 6

Engage 4Lo by pressing the button or shifting.

Step 7

Drive the vehicle forward. You will not be able to drive at speeds much above 5 mph. You use 4Lo when you climb steep hills or need heavy power.

Step 8

Listen for the same warning noises you did when testing the 4Hi. Turn the vehicle to the left and right while in 4Lo.

Step 9

Stop the vehicle and turn off or shift out of four-wheel drive to return to two-wheel drive. Continue to inspect as you would any other type of vehicle.

More Articles

article divider