2004 s-10 four wheel drive tries to engage while moving

SOURCE: 2001 Chevy Blazer 4 wheel drive

The four wheel drive systems in these vehicles are simple. The push button controls the four wheel drive computer. The computer tells the encoder motor (on transfer case) to shift. When the transfer case shifts there is a vaccum switch on the transfer that is activated which sends vaccum to the accuator under the battery. The accuator pulls a cable to lock the front axle in. This covers all s series trucks and suv's with push button four wheel drive but not with auto or all wheel. Now to answer some questions. If your push button is lit up but will not go in to four high you should try to reset the four wheel drive computer. To reset pull the courtesy light and atc fuses for sixty seconds install fuses then cycle key on and off 5 times. If your transfer case shifts but your front end does not lock in check for vaccum at the switch on the transfer case in and out. If no vaccum out replace switch motormite number 49315 at parts store. If you have vaccum out check accuator.

SOURCE: 1994 chevy s10 blazer 4x4 push button type

small sylinoid on the top of the transfer case needs replaced. easy to do. it has three vacumelines going to it just trun out and replace like a bolt.

SOURCE: four wheel drive wont engage

If you have push button 4-Wheel Drive, it is recommended that you use it every once in a while, in order to keep gunk, rust, and corrosion to build up on moving parts. The mostly likeley (though not definite) reason would be that you let the 4-wheel drive unused for so long that corrosion has built up on the parts and the actuator that engages the 4-Wheel Drive doesn't have the power to engage it past the corrosion. You'll need to take it in to be cleaned, or to have parts replaced. In the future, every month or so, engage 4-Wheel Drive and drive around in some mud, grass, sand, or any other loose ground for a bit, just to keep the parts moving and clean.

The service Four wheel drive light is to alert the operator the system is not being read properly by the ECU.

If the ECU loses contact with or position of the Transfer case actuator motor the service light will come on. Same thing goes for the front diff actuator.

So it may be a bad switch, sensor, or an actual problem in the 4WD linkage. This is not a Oil Change light that you can ignore a few extra weeks - it indicates a problem that should be taken care of ASAP to avoid costlier problems down the road.
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Harvey N Tawatao

• 3854 Answers
• Posted on Apr 08, 2009

SOURCE: 4 Wheel Drive Problem

Put the key in the run position and turn your 4wd on and off to listen for the electronic acuator to engage and disengage. If your can hear it then it's macanical and a Quick fix. On top of the transfercase on the driver's side, your going to find three vacuume tube connected to a cauume switch that may have gone bad. There common to go bad and there not the bad of a price at the Auto Zone. Check for any cracks on the vacuume line first then get your hands dirty. Good luck and keep an extra switch in your glove box.

SOURCE: My 1999 chevy silverado 1500 four wheel drive

You probably have a bad encoder motor.It is located on the side of the transfer case on the drivers side.It is black.The other problem they had with these was the switch but you have already replaced this so your next thing is the encoder motor.Hope this helps.Good luck.