Will not engage 4 wheel drive
Verify that the vacuum actuated soleniod under the battery is getting vacuum, that pulls the cable to the front diff that actuates 4WD
SOURCE: chevy s10 4 wheel drive will not engage
There is a vaccuum operated switch located on the transfer case that sends vaccum to the accuator that pulls a cable that locks the front end in. Check for vac coming in and out of this switch if no vac out replace it. This switch is a very common problem. You can find them at most parts stores in the help section #49315. please rate.
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: 1998 Chevy S10 front axle will not engage when put into 4 wheel
Normal thing that happens as long as onone (worked) on it, is the vacume hose going to the engage sevevo under the battery box has fell of on either end or is brocken on the way there. Then the once or now leaky battery acid ate up this same servo. then the cable going to the front axel breaks sticks falls off or even someone needing one climbed under your truck while parked somewhere to get one to replace their brokeen one now you don't have one then theaxel engage arm or gearset is damaged
SOURCE: 4 wheel drive service light is on, wont engage
On the full size, the front actuator is electric, not vacuum.
When in 4wd mode, a switch on top of the transfer case conducts 12
volts out to the actuator. Wire #50 (brown) is the 12v feed, and it
conducts to the light blue wire (#900) to the actuator.
When shifted out of 4wd, the switch opens up and no voltage goes to the actuator.
Check voltage at the connector for the front actuator (at the
front differential - it looks like a large bullet that threads into the
front diff.) If it has 12 volts, the actuator is the problem. If it
does not have 12 volts, check the transfer case switch and the power
feed to the transfer case.
I'll assume it is the actuator, if the plug to the actuator is getting 12 volts when in 4wd.
The way this actuator works, is it is a sealed chamber that gets heated
by voltage. When it heats, the pin in the end swells and pushes a shift
fork in the front differential. The shift fork engages a spline on the
passenger side of the differential, and boom! you have 4WD.
GM offered an upgrade to this actuator that is a motor instead of a
heated device. However, it requires a small harness addition, a spacer,
and a new actuator. It is about a $150 to $200 option.
If I were you, I would buy a new heated actuator. They are available at
most auto parts stores, and are about $90. They are also on eBay for
about $55 plus shipping. These are very easy to change - just thread out the old one, and thread in a new one.
Good luck, That actuator is usually the problem 90% of time but check the fuse first in your fuse box.
SOURCE: 2000 blazer 4 wheel drive problem
It's most likely the "four wheel drive actuator" This is located on the front differential housing. It's cylindrical shaped and has a large hex (about
1-1/4") and two wires coming out of it. Usually they short out and blow the fuse but, I've also seen where they just quit working and sometimes they just get slow to work. The "actuator" has a heating element in it and it warms up, some sort gas, causing it to expand thus engaging the front wheels. In cold weather it may take a minute or so for it to engage, so put in four wheel drive and wait for a bit and see what happens.
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