Anyone who off-roads for a hobby knows that four wheel drive is a must have. Unlike two wheel drive cars, vehicles equipped with four wheel drive (4WD) have a transfer case that takes the power from the engine and sends it to the front and rear wheels. Most four wheel drive vehicles also have a low and high range depending on the situation. Even though there is a button or shifter that is used to activate four wheel drive, auto makers include a light on the dash to let the driver know what setting is being used.
What the four wheel drive indicator light means
When you engage the four wheel drive, a corresponding light is illuminated on the dash. Vehicles with multiple gear ranges will also indicate what range has been selected. High and low are commonly abbreviated to “hi” and “lo” respectively. Some vehicles may only have an indicator for low range as high range is the default. Refer to the owner’s manual of your vehicle for specific information on your four wheel drive system.
Newer model vehicles have started using electronics to control the four wheel drive. Some of these electronically controlled systems have a 4x4 automatic mode. This mode keeps the vehicle in two wheel drive mode for most of the time until extra traction is necessary. The car’s computer monitors the wheel's rotational speeds and if it notices any slipping, it will send the power to all four wheels to keep the car moving.
Vehicles that have four wheel drive systems tend to have a separate light to indicate an issue with the system. Usually labeled “Service 4WD”, when this light comes on, a code will be stored in the computer’s memory to help identify any issues. Depending on the problem, the four wheel drive may be disabled temporarily. Sometimes if you haven’t used four wheel drive in a while, the computer may think that the transfer case isn’t lubricated properly. If your Service light turns on, try engaging the different gear ranges and driving around a little bit to move the oil around. Hopefully, the next time you start the engine, the light will be off.
Is it safe to drive with the four wheel drive indicator lights on?
Using four wheel drive in slippery situations makes a huge difference to the vehicle's driveability. You should never engage four wheel drive on dry pavement. Four wheel drive requires some slippage to occur between the front and rear wheels which is why it’s perfect for gravel, snow, and sand. On dry pavement, the grip prevents any slipping from happening and enabling four wheel drive will overstress the drivetrain. Vehicles equipped with automatic four wheel drive switch between the modes on demand so you don’t need to worry about switching it yourself.
If your service light is on or if your four wheel drive system doesn’t seem to be working properly, ask one of our certified technicians to help you diagnose any problems.
This article originally appeared on YourMechanic.com as What Does the Four Wheel Drive Warning Light Mean? and was authored by Spencer Cates.