I have a 93 f250 4x4 with the 7.3 idi non turbo that wont shift out of first till its over 3000 rpms. I read the sticky on the tps adjustment and have it set at 1.2 at idle and I could only get it to go to 3.8 at WOT. The truck shifted perfectly before I put it in 4lo, then it got stuck in 4lo. I was able to get it back into 2wd, but I still cant seem to get it out of first till over 3k. I just put a new TPS on and adjusted it to the above readings. Any help would be greatly appreciated.

 

oh wow.interesting.so you need to suspect the sensor in the t-case.it's just a basic little bugger that tells the trans if your in 4lo or not.you can't miss it.the only electrical plug there.inspect the plug/wires and if ok,pull the sensor.replace if needed it has a little ball on it.it might be frozen up.see if you can free it up.
you should grease up your 4wd linkage every year or two and shift it once a month to keep her shifting smooth.might want to check/flush the fluid while your here.it's a couple quarts of ATF.
tip; a gear lube cap screws right onto an atf bottle for easy access/pour for the fill hole.

 

When you finally got it out of 4LO, did the "LOW RANGE" light go off?

 

Thank you for the replies! I will check the t-case sensor, and the I filled up the t-case right before this happened. The 4x4 light on the dash did go out when it finally came out of 4lo. On a side note, I did notice it was wierd that the truck would go into 4lo but not 4hi.

 

nice catch 250, 25 year old switch stuck, trans thinks its in low range and changes shift points to extreme rpm...

 

yeah but the 4wd light turned off.so it told the light to go out,but not the trans control unit? this is an odd one.

 

im leaning more that way myself, I checked the VSS(cleaned and re-installed), the electrical connector where the shift cable goes, all the relays. Im kinda at a loss... I think im going to change the transfercase sensor and see what happens. I also dont know what that sensor is called.

 

im at a total loss as well brother.the problem happened exactly at the time your t-case was shifted and got stuck.it's got to be related to that switch/connection.maybe you'll see the clip that goes on the sensor is screwy or something.it's making the 4wd indicator function properly though.keep us posted.very interesting.
are there any codes?

 

No codes that I could pull, the OD light is not blinking, everything is running perfectly, except this.....

 

Disconnect that switch on the t-case first, just to see what happens. I **THINK** with it disconnected, it's the equivalent of an open circuit, so the PCM would interpret it as NOT in low range. Worth a shot anyway.

 

Good call....(i wish I thought of it) I will give it a shot in the am. Its too dark and nasty out right now. I appreciate all the help!

 

Well no change with the sensor unplugged, so it looks like I might have to take the transfercase off and see what is going on inside it, unless someone else has a better idea.

 

So i pulled the tcase off and opened it up and the shift forks seem to be slipping out of the metal bracket that moves them into 4hi,4lo and so on. One thing i noticed is when you shift it into neutral i could still drive fwd and reverse, any ideas?

 

well since you know the t-case isn't any good, replace it and go from there.