1994 GMC Sierra 4x4. Only drivers side rear wheel and passenger side front wheel seem to engage in 4 wheel drive. What could be my issue? No traction while plowing snow.
What could be my issue?
Maybe nothing. Despite what the name suggest, 4WD is only meant to power both axles.
The two wheels on an axle must be allowed to turn at different speeds (otherwise you wouldn't be able to steer). That's the job of the differential. That means one wheel on each axle can slip. And if you have a wheel with zero traction on each axle, then it can defeat a 4WD drivetrain and you get stuck.
Some vehicles have what's called locking or limited slip axles to mitigate this issue. This limits the amount of wheel spin and helps you get going. That can be an expensive proposition though.
But there's an easy trick that every 4 wheeler knows, and it can help you get out of a situation like you describe:
Apply a little bit of brake at the same time as GENTLE acceleration. The brakes will limit the amount of wheel spin, which allows the differential to apply some torque to the wheel with traction, and hopefully get you out of the snow/mud/whatever.
