ok have no clue what is going on here. First I have an AWD/4hi/4lo T-case on a 99 Expy. For awhile for some reason the front would not engage. I know this because while on snow I had the back wheels spinning and nothing from the front. Then I got waylaid in the barrow pit and spinning the tires and moving forward and backward finally got back on the road. (12 inches of snow so lots of tire spin) anyway the front acted like it was locked up or had a spool in it. I put the vehicle on a lift started it put it in gear and all 4 wheels were spinning. So now it won't go out of 4hi. There is no dash light saying it is in 4x4. The light worked before the problems started. I have removed the front driveshaft so we can still drive it. Any suggestions?

Thanks
Robert

 

Does your shift motor appear to be operating correctly ?

 

in awd and it's on a lift all 4 wheels should spin, in awd if there is a lot of snow good chance the wheels won't spin, that is what 4x4 high or low is for, leave the driveshaft in there is a good chance you'll burn up your transfer case letting it free spin, does the light come on when you turn the key on? does the light come on in 4x4 low and you say it acts like there is a spool in the front? how so explain what it's doing

 

Sounds like a shift motor problem.

This is not an AWD transfer case. This is an automatic 4wd transfer case. There is nothing different about this t-case excpet that it can be set to automatically engage 4wd when a front to rear wheel speed difference exists.

You can not damage the t-case or axle by removing the front driveshaft.

I think the "fight" in the wheel you feel is the t-case being stuck in 4wd now. That would probably be because of a shift motor malfunction.

You absolutely should have had some front wheel drive with all of the spinning you report. Could be the faulty shift motor again. I would remove it from the t-case and test its operation.

When wheel speed sensors, detect front to rear differences, they engage the front drive in a somewhat variable fashion. More often with a bit of a thunk as most of us owners can attest to. There is no center differential like AWD that could allow the rears to spin and not the fronts. It is a locked front to rear connection when engaged.

 

While we're on the topic, is it a good idea to engage the 4x4H and 4x4L every once in a while to keep it all lubed and such? I hardly ever use my little 4x4 switch on the dash as my truck is used to tow my TT down the asphalt.<O</O

 

Your front end components are always spinning as you drive down the road in the A4WD setting. No need to engage 4H or 4L to lubricate things.

 

That's true but it's a good idea to work the motor and transfer case once and a while, I do.

 

I was guessing the shift motor as well. How do I test it? Don't know if the light comes on when I turn the key on, will check when I get home. As far as acting like a spool I think that may not be totally correct but it is definately binding and pops and bangs when I go around corners or into parking spots.

 

the binding and popping is normal going around turns if the parking lot is dry

 

One thing you might try is disconnct the battery, give it 10-15 min then rehook it up. My expy has a weak shift motor in it and I did not get it changed out before winter, and with 15* below the old is working for now. This is not a permanent fix, but it may get you going for a while. You may also have toback the truck up quite aways to get it to come out of 4 x4 hi.

 

Are your tirs all the same size. It was just talked about on here on another post. If you have different ties on your truck front to back or what ever ten the speed of your drive shafts are not the same and the transfer case will try to engage. Just some thing else to look at. Instead of pulling yur drive shaft just pull the fuse. This disengages the auto 4 x 4 andwill give yo better insigt to what is haqppening.

 

Somebody asked if the lights came on when the key is first turned on. The 4X4 Low light comes on but not the 4X4 light. (edit: Both lights come on)

Drive shaft is already removed as I know driving around on dry pavement in 4 hi will ruin things. I tried the backing up thing backed all the way down my street (about 1/4 mile) this did nothing.

Didn't know there was a fuse. I am guessing this is not a fuse like under the dash but one under the hood?

 

The fuse is under the hood in the black box, driver side in front of the windshield. Look in the owners manual and it will tell you which fuse is for 4x4. I have had to pull mine out because whenever my A4WD kicks in or I put it into 4x4H or L it sounds like the front end is binding up and clunks like crazy. The problem you are going to have is getting it out of 4x4H before taking the fuse out. If you remove the fuse you basically take away the electronic mechanism for turning on and off the transfer case shift motor. You need to get it into A4WD before removing the fuse. I'm going to take my transfer case shift motor off this weekend to see if it is defective since some say it might not be fully engaging.