I discovered that my 4wheel is not working the hard way when I got stuck in the snow recently. Today I put the truck in 4wheel and then tried to turn the front drive shaft by hand and it spun freely. It did so in both 4 hi and 4 low. The truck does however go into the lower drive ratio when its in 4low, but no movement from the drive shaft. Any ideas on why its not working? It's a 91 V6 Auto. Thanks .

 

Any Ideas?

 

does it have manual locking hubs on the front wheels? if so u need to lock them ,move the dial from free to engaged.

 

The truuck has ADD. Like I said, the front drive shaft won't engage, so its a problem with the T-case. It spins freely while in 4wheel with the truck stopped.

 

Is your dash light on which shows "4WD"?

 

Yeah the light goes on when I shift it in. I traced the leads for that light and it goes to the front diff. The 4wd light would seem to indicate that the ADD is working. I am wondering if it may be something simple before I tear out my t-case.

 

Does it have push button 4wd, like the newer automatics, if so I think there is a solenoid that switches from 2-4. I'm not an expert on autos, mines a 5 speed, not that I'm an expert on them either but I know a little more

I do have a factory manual I can email to you if you want to look at that. If so send me an email address.

 

It's a floor lever shift for 4wheel. That would be killer if you could send a scan my haynes is not very helpfull.

stephenskis@hotmail.com

 

Check the vacuum lines for any leaks. ADD won't engage fully if there is a leak in the lines.

George

 

Here is the 93 FSM, it should be about the same as the 91: http://personal.utulsa.edu/~nathan-b...fsm/index.html

 

thanks man!

 

Your t-case should be the chain drive (VF1A).

 

Thanks again for th FSM. Based on the drawings I'm guessing it's the linkage to the front drive shift fork or the fork itself. It's a seperate linkage for the hi/low so thats why it can shift into low and not 4wheel. I'll take a look tomorrow.

 

I've heard the chain drive t-cases are weaker but I've never seen a failure first hand. Let us know what you find out. Good luck.