Four Wheel Drive  is not working?

Another tech tip from Clutch & Transmission Technicians.

Modesto Ca

Have you ever gone to the snow or mud and find out to late that your Four wheel drive is not working?

Not Now!!! Does your 4wd work?

Not Now!!!
Does your 4wd work?

Most people that have a four wheel drive vehicle, only use it about once or twice a year in California.  Many times, they find themselves stuck when they get there as there 4wd is not working. Unlike the old days where you manually locked the hubs and could get under the vehicle and put the transfer case in 4wd if you had a problem. Now you have a computer system, fuses, wiring, motors and switches that run the 4wd. Therefore when you need it most, it is unlikely that you will get it working if it fails without visiting a shop.

The first thing that everyone should check before leaving on a trip to the snow or mud is that it is working.  This can be done on your street at home. Must be on a concrete  or asphalt road, not dirt.

Just because you feel it engage the transfer case and the light says 4wd, does not mean that the front hubs are locked. It will gear down and feel like everything is working until you get there and have no front wheels driving.

!!! Last year, we had an older gentleman walk out of the woods 5 miles after getting stuck while hunting because his front hubs were not working. This can be avoided by doing a simple check before leaving on that trip!!

We will start by explaining how it operates.

When you actuate the 4wd. It puts the transfer case in the range you selected. It also locks your front hubs to give power to your front wheels. You can feel if the transfer case is engaged as the vehicle may clunk as it engages and you will notice the vehicle is in a lower gear as driving. The best way to check and see if the hubs are engaged is to turn your wheels all the way and drive forward. You should be able to feel the vehicle bind and not roll smoothly. If you can not feel  a bind. Then your hubs are probably not working. (Be carefull driving in 4wd on pavement as the vehicle will not steer the same and is very difficult to turn sharply)

Other common 4wd complaint

We have a carwash close to our shop which brings up another common problem we see. We get quite a few customers come in with a complaint that there vehicle is shuddering and vibrating and hard to turn.  The first thing we ask them is if they just had their car washed. When having their car washed, they wipe down the dash and often hit the 4wd button engaging the four wheel drive. So if you have recently wiped or had the dash wiped down. Check to make sure the 4wd has not been activated

2003-2007 Chevy/Gmc Trucks

This type of switch is the most common to fail. Notice the N for neutral.

This type of switch is the most common to fail.
Notice the N for neutral.


If you have one of these 4wd trucks and loose all gears or find it putting the transfer case in 4wd randomly. There is probably a problem in the transfer motor. This can be very intermittent which can make it hard to diagnose. If you loose all gears and it feels like neutral but there is a loud grinding noise when you try and put the vehicle back in park. Try this simple trick. This may help having to tow the vehicle. I will first explain what might be happening. When you turn your ignition on. The computer checks the 4wd switch. If the encoder ring in the transfer case motor is failing, the transfer case can be placed in neutral during this process. Try cycling the key on and off a few times and retry. The 4wd light on the switch should go to 2wd or auto instead of the neutral light. Try a few times as this will usually work to get the vehicle to move again. Sometimes the motor can fail completely and this will not work. If this works, take it to a shop to have checked and repaired as it will probably happen again.

Thank you

CTT Transmissions blog.