4wd low ok, no 4wd hi

stikxs · June 12, 2006

1998 Sierra Z71 auto

Short story: press the 4wd high button and the hi and low both flash together a few times then it goes back to the 2wd light. Press 4wd low and you can feel/hear it engage and the light turns on correctly. Press 2wd when already in 2wd and the 4wd lights flash the same way they do when pressing 4wd hi.

Long story: about 5 months ago I engaged the 4wd hi since I hardly ever use it and just wanted to get all the parts moving a little bit. Well it turns out someone had been under there before and some of the wires weren't routed correctly when they were done. The driveshaft on the drivers side to the front grabbed the o2 sensor wire loom that was there and tore that right out of it's connectors. It also pulled one out the side of the transfer case, not positive which (driver side connector, about 6 or 8 pins), I know it did make my speedometer stop working. After plugging that back in it did let me switch back to 2wd and I can go to 4wd low, but it won't go into hi. I never got a light/code from it I don't believe. It drives fine in 2wd and seems ok in 4wd low, though I haven't really driven much more than idle in 4wd since.

Also last night I was listening to it while pressing the buttons, and when you press the 4wd hi you can hear something I assume is the actuator moving, it doesn't sound like anything gets 'engaged' just sounds like a rod moving out or a servo arm turning or something like that, not anything near what 4wd low sounds like. Also when I press the 2wd button when it's in 2wd already, I hear the same noise and both of the 4wd lights flash the same as if I pressed the 4wd hi button. Another odd thing is that even though I can press the 4wd hi button and it will flash a bit then go back to 2wd, it won't do it in gear like how you're supposed to be able to switch to 4wd hi in gear, it will only do something in neutral for both hi and low. I replaced the switch already, but that didn't fix anything. Haven't checked the actuator since it wil shift into 4wd low I figure that is doing it's job, but I guess I should check it anyway. It seems like there is some logic controller box somewhere that is not working right since it won't do anything in gear. When I press a button I can hear relays or something clicking that sounds like it's in the dash.

stikxs · June 13, 2006

I unscrewed the front actuator and it wasn't moving at all. Unplugged the 2 connectors on the tcase and saw a bunch of wires with insulation worn off. Taped them up, and put everything back hoping it was the wires, but it still behaved the same. Came inside to type this post up and thought about something to go back and look at real fast, and d**n if the 4wd didn't start working. All I did was turn it off, come inside, and go back out, and it magically fixed itself...

ChevyTech007 · June 13, 2006

Kool.

HyperBuzzin · June 13, 2006

saw a bunch of wires with insulation worn off. Taped them up .... and put everything back .... but it still behaved the same .... go back out, and it magically fixed itself...

<{POST_SNAPBACK}>

I need to get me some of that magic tape !!!!

Glad things worked out for ya !!