tackepj

Update: Thanks for the help! It was the actuator. I got the new part from NAPA, it was $96. Sure was an easy repair, and 4WD works fine now. Interesting that GM would use a heated actuator. I just figured it was a little solenoid in there. Oh well--I know it's the original, and it lasted 12 years and 140k+, so that's pretty good life. Probably the only time I'll ever have to replace it. Thanks again.

dgilfillen, Thanks for your help. I checked voltage at the connector near the front diff, and it's getting 12 volts when in 4WD. I also went and re-checked the driveshaft, and I was wrong, it's definitely turning when in 4WD. The truck still isn't engaging into 4WD though. The hubs aren't locking, and I can drive in 4WD for a while and it never goes in. Looks like the T case is fine after all, so it's probably the actuator, right? Is that hard to replace? Any tips? Thanks, Phil

Just an update. I know for sure that the hubs aren't locking and that the front driveshaft isn't turning. I put the truck in low range out in a field and let it creep in 1st gear, and I hopped out and the shaft is definitely not turning. Same thing in reverse. Kind of surreal to watch your truck drive along without you in it... The only fuse (25 A) I could find is in the dash panel by the steering wheel, labelled 4WD or something, and it's fine. There is a space for one labelled "transfer case" but it's empty. Must be for the push-button T case or something. I called the shop that did the clutch and they're not sure, but asked me to bring it in. Any idea how the system works? Do the hubs lock with a solenoid or something or do they need input power from the front axle?

I have a 95 K1500 W/T, 142k, with Insta-trac and the lever on the floor. I tried 4WD-hi yesterday on a dirt road, going about 15 MPH, but it never engaged. The lever moves fine. I tried while stopped, too, and it never engaged. Tried forward and reverse. The light never went on, and I could tell it never engaged (still could spin the rear tires). It shifts fine into low range, but still not into 4WD. I can tell the hubs aren’t locking either. There’s no clunk or noise or anything, it just won’t engage. No binding around corners. I never had this problem before, and it worked fine in the snow all winter. Any ideas? The only thing I can think that’s changed is I had the original clutch replaced a few weeks ago. Not sure where to start. Thanks