Chevrolet Repair: 4x4 chevy trck, chevy info, differential assembly

Question
Van
   I have a 1988 chevy k2500. The truck has not been driven much lately. We plow with it. The four wheel is engaged with the shifter on the floor. It would go to the 4x4 position but the front wheels did not engage. The light in the shifter display didn't come on. Later it just engaged, then went out, the driver told me it came on a couple times but then went out. This seems to be some kind of connection. The front hubs are automatic, if that is important. Any info would be great.        Thanks    Jim

Answer
Hi Jim,
Actuator is the word you need to know.
It is a thermal expansion gizmo, located on the front side of the right front axle tube, where it connects to the differential assembly.
Those actuators are pretty dependable, but are the most common problem on those trucks.
It screws out...nothing falls loose inside, and hardly any oil is lost.
There is a spring loaded yoke inside that the actuator pushes against, and connects the axle shaft to the diff, and turns on the 4X4 light.
You can check the 4X4 fuse, and it may or may not be blown, but the actuator is what will probably need replaced.
I will send a few links to a site that sells aftermarket manual operated systems. I haven't seen one, but they sound like a good possibility.
Or you can get the updated replacement from Chevy parts, but ask about the wire harness adapter if there is one for yours.
One of the links I am sending has a pretty good troubleshooting page, but disregard the refference to the driven axle, cause neither is driven till that actuator connects them.

www.4x4posi-lok.com/PDFs/troubleshootguide.pdf

offroadltd.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=ORL&Product_Code=PSL600

www.4x4posi-lok.com/

And here is a site for a great deal of Chevy info. To ask a question you need to sign in, but it is free, and you will love it.
www.chevytalk.org/

Van