Question about Cars & Trucks
You need a OBD scan tool to get the codes. You can get a basic one that will show engine codes for fairly cheap. Abs codes etc will be on a better model. Garages will check them for cheap too. The 4wd actuator is prob siezed from not being used for months at a time. Take it out and see if you can free it up. It should be fairly easy to get at.
Posted on Nov 20, 2014
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Posted on Jan 02, 2017
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. The actuator is usually the problem 90% of time but recheck all of the wire harness just to maker sure there is no short before replacing any parts.
Posted on Jan 02, 2010
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Yeah your right about waer but you might be blaming the wrong part. With the truck up on jack stands ( all wheels off the ground) have a helper drive the truck at the speeds that make the most noise you'll find it in the front axel or fround U joints or drive shaft splines ( drive shaft jumping ) You watch the parts moving and the joints or the cable that shifts the ront axel in and out not moving all the way it uses a vacume motor under the battery that has a cable going to the front axel. the clutches that are in the front axel have clips on them that hold the side gears that engage and disingage as you turn it on and off the clips break get lost fall off were out and let the side gears do as they please and they runinto each other a click and pop/ the cable and the shift fork that move them also fail but not htat much as the cable fails and the vacume leak pulls on a spring in two wheel and it may not be pulling hard enough/
Posted on Sep 17, 2010
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There is a clip on the pumpkin (front diff) that the 4wd cable connects to that is common to break. Easy fix, inspect the cable where it connects to the pumpkin and repair any damages found.
Thank you for using fixya and keep us posted.
Posted on Nov 17, 2010
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