Hello all! new member here,

I just purchased a really clean mostly garage kept 97ford f-150 lariat 4.6 auto ESOF 4x4 with 92,000 miles it was a one owner vehicle who iI am friends with .Everthing works in the truck like it should. The problem he had was he put the truck in 4 wd one day in the winter and it wouldn't disengage from 4wd, So he took it to the Ford dealership , they put a new transfer case motor and 2 quarts of transmission fluid in ,but it didnt fix the problem, they said its a gem module and on back order, well it sat there for 6 months and i just purchased it. When he left the dealership it was close to closing time on a Friday, he was going down the highway and now the transmission wont shift into overdrive and sort of bucks like it wants too, but doesn't go into overdrive. Never had this issue previously. The od button does work on the shifter with no flashes or anything . I'm curious about the 2 quarts of transmission fluid, is that needed when changing the transfer case motor? I still dont have a new gem but I did pull all the fuses and the #23 fuse 4wd actuator fuse was good but the pins were real dark colored compared to all other fuses, i cleaned it up, didnt really make a difference. the 4wd switch i really dont hear any clicks when i turn it , but it was stuck in 4 wd before i cleaned that fuse and after i put it back it was out of 4wd, but if i now put it in 4wd it doesnt do anything . Is it normal for the truck to whine when driving down the road? obviously its not going into od and only getting up to about 45 but it seems loud to me and not normal? I've never driven one of these at all so i dont no how they normally drive and sound. I'd appreciate any help

 

The t-case holds approximately 2 qts so I'm guessing they swapped the motor and replaced the fluid and didn't touch the actual trans-- point being your OD issues are likely completely unrelated to your 4wd issues.

The GEM gets blamed for anything and everything but if your only symptom is 4wd problems (I think your OD problem is self-contained) I'd be skeptical the GEM is unhappy

 

The first step to fixing it is to get the codes read. I recommend Forscan which is free at www.forscan.org. Otherwise, you'll need a good independent shop or a Ford dealer. The places that read codes free CANNOT read these codes.

 

Not too happy with the dealership so far they put a 454.00 transfer case motor on and that wasnt the problem. I'm not all about them throwing parts at it without knowing whats actually wrong, especially with their rates. How do i get this free forscan thing? I looked on website but not sure how it works?

 

This may not be your problem but one thing to consider is if your tire sizes aren't the same and the tread wear thickness even for each tire on 4x4's you can have shift problems especially if the tire diameter on rears are larger than front.

Just some info. The following fuses are in your system. Junction Box under dash; Fuse 13-15amp, Fuse 23-10amp, Fuse 29-5amp. In Power Distribution Box; Fuse 17-30amp.
There are 3 relays in the system; Transfer case electric clutch relay (in RPO relay block) with H2L and L2H in Transfer case shift relay module (behind center of dash).
There is a ground for the relay module in lower right kick panel.

 

Forscan is a program that can download to a laptop or a phone. Then you'll need an adapter to connect the laptop or phone to the OBDII port. The Forscan website tells how to select an adapter. I bought mine from Amazon for less than $30.

 

Also worth noting the GEM module from Ford is discontinued and has been for a long time. So your only chance for one is to have yours repaired.

 

A trip to the junkyard may be needed.

 

Well i found out what the problem was sort of, put another GEM module in from a junkyard and the 4 wd still didn't work, so the next day i replaced the 4wd selector switch on the dash and everything worked including the transmission problem and 4wd issue. so i was curious if old gem was good or not , so i put it in and it was stuck in 4 wd again, i didnt drive it to see if tranny was still not going into od, i should have. so i put the new gem in again and everything works. I don't know why it didn't work at first but, i'm sure happy I dont need a tranny. So check your 4x4 switch first and then maybe gem (hard to find and expensive). thank you guys for the help. there was a good you tube video on 4wd issues by macadoo or something , it really helped troubleshoot my issue