..on my wife's 2002 Tracker ZR-2. We found out that she had no 4WD, either low or high. The transfer case shifter seems to work OK and the 4WD dash light illuminates. I crawled under the vehicle to check it out. With the ignition off and the t-case in 4 high, I could turn the front drive shaft by hand. With the ignition on, the front axle engaged and I could not rotate the front driveshaft.  This simple test tells me the t-case is not operating. It doesn't make any noises in 4 high when you're going down the road, we found it didn't work when she got it stuck.

I t/t my local Chevy dealer and they have had no problems with Tracker t-cases. My guess is that is may be something simple inside the case, but I'm going to have to pull it to find out. She may have forced the shifter and bent something internally.

Has anyone had a similar problem? Has anyone had one of these cases apart? Any suggestions?

I don't think you're necessarily correct about the T case being at fault.  When you engage 4WD, the front driveshaft is connected via the T case gears to the rear driveshaft and the input shaft, so it will not be able to be turned by hand. 

Although you said the front axle engaged, try again with ignition on and T case in 4H; this time try to turn the front wheels (jacked up).  If the axle has engaged, the wheels will turn in opposite directions, because the front driveshaft  is connected to the axles, but cannot turn.  If the wheels rotate in the same direction, or only one turns, the axle clutch has not operated.

1st place i would start would be the air pump inside the front bumper on the pass side, with the ignition on, in 4wd hi or low you should hear it cycling, you'll have to put your ear beside the bumper, if you hear nothing at all the pump is not running.    i'm sure others, will chime in here...

Thanks for the replies, I appreciate it. To clarify, I was under the car with the ignition off and the t-case in 4 HI, and I could turn the front driveshaft easily. I then had someone turn the ignition switch to on, I heard a click from the front axle, and I could no longer turn the front driveshaft. I'm still thinking it's the T-case; however, I will listen for the air pump to activate.

 

My fault for not reading your post carefully.  In 4Hi (and 4Lo) you should definitely not be able to turn the front driveshaft (this is the shaft from the TC to the front diff - yes?).  It should be in mesh with the rear shaft and the drive from the transmission,

When  the ignition was turned on, you couldn't - that proves the front axle clutch was engaging, but the TC had not - you had it right.  Must be something broken inside the TC.

A couple of friends and I took the case out the vehicle and disassembled it. We found small pieces of metal in the oil when we drained the t-case. Once the front of the case was removed we could slide the synchronizer to the front drive clutch and engage the front driveshaft. We were still finding small pieces and metal and couldn't figure out where they were coming from, as all the gears, synchronizer and drivechain were fine. We had to totally disassemble the case into its 3 sections and remove the gears. etc. We found that the shaft that moves the shift fork to engage the 4WD has a spring, clip and washer to give a smooth shift between 2Hi and 4HI. The shaft on the other side of the shiftfork was missing its washer and clip, and we believe that accounted for the metal we were finding. The missing washer and clip were allowing the shaft too much play and didn't move the fork far enough forward to engage the front drive clutch. We're not sure if there should be a small spring on the other side of the fork shaft. We figured my wife must have forced it into 4WD too hard, forcing the shiftfork shaft to the point where it broke the retaining clip. It also looks like the end of the of the shift handle, where it engages the shift shaft in the case, is slightly bent.

I'm not a technical writer, so I hope my explanation is helpful.

Yowch...


...mental note: remind wife to be gentle with the 4x4 lever...

Hope this helps: