i was up at pismo last weekend, me and a buddy were pulling out our friends stuck trailers [sand]. smelled burning rubber on the last pull, guess i was bouncing too much, shredded the boot on my output shaft to the front diff. was checking to see if anything was damaged, everything looked ok but it would'nt spin the front wheels. sounds like the transfer case is engaging, and when i put it in low the rear gets the reduction. with the 4x engaged you can't turn the front shaft by hand, in 2x you can. when tying to shift into 4lo in gear the neutral light used to come on, now it does'nt. hard to trouble shoot with all this auto/electonic crap. anyone have a link to manual ? i've tried to get one for awhile, found out today haynes is about 5 miles away but thy're doing inventory this week, so i can't get one till next monday. going out to jack it up and try to turn the front wheels while it's engaged see if it's the front diff. any ideas or links let me know. e

 

well with 4wd engaged and you can't turn the front shaft that means that it is engaging in the transfer case, you said you were in sand maybe some sand got in there and caused some binding, unlikely but something happened or that boot would not have been shredded...I would go check out your front diff...on a side note when going into 4lo, my neutral light never comes on. Doesn't bother me just so long as I hear that locker engage that is all I care about. Good luck with finding the problem, your truck sounds sweet!

 

thanks, it was the hero of the day until it broke, oh well we got everyone unstuck first. i jacked it up last night, both front wheels are engaging when in 4x. without the ability to unlock the hubs, it's hard to tell what's going on. everything seems right, except the boot of course. have to get it on a rack to see if the t-case is getting power to that shaft. did'nt hear anything let loose, no grinding noise's when engaged. guess i'll take it to the shop and let them have a look, need a trans fluid change anyway. thanks, e

 

Did you check the engager on the diff they will stick some times.It has wires going to it, on top of the chunk passenger side.

 

Which t-case is this? Regular, or the AutoTrac?

Correct me if I'm wrong... but my Auto-Trac case would engage/disengage the front driveshaft from the t-case, AND the front differential. Here is something I dug up from the Avalanche guys: (AutoTrac)

2HI: Front axle disconnected, transfer case provides no power to front, lock solenoid de-energized.

AUTO 4WD: Front axle connected, transfer case routes power to front, but energized lock solenoid prevents power transmission. When slippage detected, solenoid de-energizes, providing power to front.

4HI: Front axle connected, transfer case routes power to front, solenoid denergized allowing power to front.

4LO: Same as 4HI, but an extra stage of gearing is enabled in transfer case, providing lower speed but more torque to front and rear.

NEUTRAL: Front axle disconnected, transfer case shifted to disconnect front and rear properller shafts from transmission.

Here's an exploded view of the front diff on 1500 trucks.

 

Shop manual quote:

 

thanks for the info, i do have the autotrac case. i unplugged everything cleaned the plugs and replugged everything, seems to be engaging. after reading that info it still seems like if you put it in 4hi/lo or auto, it still engages the front axle which spins the input shaft while moving. unlike my other truck with manual hubs, where i can disconnect the wheels to see if the t-case is spinning the shaft. can you think of another way to test it other than lifting the whole truck, or punching it on a loose surface and watching the tires ? what do you think about unplugging the black engager on the front axle ? think the t-case will still engage ? like i said before the t-case goes into low, i can hear it clunk, and the ratio drops. when i jacked up the front while in 4x the front axle is engaged [can't turn wheel], at this point i just need to be able to test to see if it is working. that disintigrating boot may have hit a wire hard enough to knock it loose without unplugging it, and the plug unplug may have fixed it. e

 

i just reread that info, any idea where that lock solonoid for the auto trac is ?