Was helping my brother in law with his newly acquired 95 GMC suburban
4x4. No 4wd lights on the floor shift, no front axle engagement. was blowing the 4wd fuse.Did some research on the interest and found these units have some thermally engaged front actuator on the front drive axle that is problematic.
Got under the truck and inspected the unit (about the size of a larger O2 sensor) The lead wires into the sensor where literally melted together (that explains the fuses blowing) and the wires were loose and pulled out of the actuator.
New ones were $70+. Went down to the Upull yard to see if we could get lucky. went through 6 trucks or so, all had the actuator pulled, or was the wrong one. Truck 7 we got lucky.
Put it in, and the fuse does not blow. Lights on the floor shift light, and the 4wd works now. Got real lucky on that one.
I found there is a update kit for these that uses a newer actuator that is more reliable. It was a lot more money and requires a wire harness modification. Since he is not going to keep the truck long, we decided NOT to go that route
bob