I have a 2008 f150 4x4 and electric shift transfer case. The t-case is in 4 wheel drive but the 4x4 switch is off! Solenoid bad?? If I unplug it will it default back to normal? Going to screw with it tomorrow morning, 10:30pm now and trying to get an answer before tomorrow.

Thanks
John

 

I think you have a vacuum leak. The 4x4 system in that model year truck depends on vacuum to keep the system in 2WD. If there is a leak, it defaults to 4WD.

- Jack

 

Partially correct, Jack. The IWE's (hubs) are controlled by vacuum, but the transfer case itself is controlled electrically.

https://www.f150online.com/forums/ar...then-some.html

 

That's the story of my life - I know just enough to get in trouble. Still, wouldn't a vacuum leak cause the problem he's describing? I recall another thread many years ago where the truck was stuck in 4WD and the problem was traced to a vacuum leak.

- Jack

 

We actually need more details - are the IWE's engaged or is the transfer case engaged, or both?

It's all electrical at the core - the transfer case motor engages the front driveshaft electrically, the IWE solenoid allows or blocks vacuum and is also engaged electrically. Lack of vacuum at the IWE engages it, vacuum retracts it.

Here's a better thread at a sister forum that describes system operation:

http://www.f150forum.com/f72/how-dia...m-esof-186872/

 

That makes sense, glc. I think you've given John the information he needs to figure out the problem.

- Jack

 

Thanks for the info all, this is what I found so far.

Taser is ok, took driveshaft off and case works normal.

Front axles are engaged"lock in", so as I'm driving the rear is turning like the hubs are locked. I had this problem a couple months now (on and off) and now as of yesterday is steady!


I replaced that little vacuum solenoid behind the battery about two years ago, is this the problem? Or something else?


Thanks again

 

Read the linked threads for specific troubleshooting. You are saying that the transfer case is working properly but the IWE's are staying locked? That's an IWE issue, you have to do the vacuum tests.

 

I did read the write up which was very good, doing vac test tomorrow.

Thanks

 

Did the vacuum test and all looks good and the 4x4 system works fine non (for now)! Had vacuum at the valve on firewall and at hubs, did the bypass test and all worked. I don't now what the problem was, guess I keeps my eyes on things for a while.

Thanks all