TransferCase Disengages Under Load!?

Question

I own a 2004 F-150 New body style. I can engage 4wd and it works until it's needed. As soon as a load is put on the transfercase (whether it be the slightest grade or high rpm wheelspin) it will disengage the front end. The front driveshaft disegnages and does not spin. It's either switch related or tcase related. I am siding towards transfercase related, I imagine its the electric shift motor (it's Shift on the fly). Does this sound like the shift motor is not engaging all the way or what? The shift motor is only $100 used.

I am out of warranty guys. I also know it's not my IWE's, there is proper vacuum and the front driveshaft is what disengages...if the front driveshaft was engaging and the front tires not spinning then it would be the IWE's. Also, the 4wd indicator light stays on when the front driveshaft disengages.

Answer 1

Probably not the shift motor. I have seen more problems on these from the front Independant wheel end hubs. The front hubs on your truck are vacuum actuated when you switch the transfer case to 4wd. These can develop a vacuum leak in the line or at the solenoid on the front axle, which will cause the from locking hubs to unlock when vacuum is lost. A loss of vacuum upon acceleration or load furthur makes me think you have a vacuum leak in the front hub locking system. Have it checked at the dealer or a reputable shop that knows about your 4wd system. A quick check of the lines and solenoid can be done under the truck on the passenger side, in the area under the starter.

Answer 2

You are probably right about the shift motor but before you spend any money you should get this diagnosed by a good shop. There could also be wear on a gear or pin that is causing your problem. You could do the repairs yourself to save money but the diagnosis should be done by someone competent to do so as this may save you money in the end.

Answer 3

Who cares what it is, it should still be under warranty