Originally Posted by eagleclaw

Hey Ricky. Thanks for the additional info. I will definitely check for hairline cracks in the vacuum lines. I am also going to check the Transmission Range Sensor Switch part # 4L3Z 7E440 AB located on the left front of the transfer case. I saw that JackPiner57 had a similar problem but the opposite of mine. His truck stayed in 4x4 drive when hot and would shift back to 2x after the truck sat and cooled down.
I normally work on my own truck but this time I was told by several people that I need to find a mechanic who could rebuild the transfer case. The mechanic I used came highly recommended. I would tackle just about any job but this called for a lift that I did not have.
He looked at the transfer case and shift linkage and informed me that he did not feel that the transfer case was the problem. He stated that the linkage was sloppy and was not engaging the shift fork all the way. I did have some binding problems with the linkage from time to time. I hit it several times in the past with white lithium grease. While he was working on the linkage, I had him change the automatic tranny fluid, filter and gasket. I also had him replace the rear transfer case yoke seal. (starting to leak slightly). After he changed the linkage, he took it for a ride and everything seemed to work smoothly. I asked him to drive the truck for while and then he noticed that the truck would not shift back into 4x4 when hot. That's when he swapped out the 2 vacuum switches on the firewall. I don't know if he checked for vacuum leaks on the lines. I will ask him and then check them myself. I am really hoping that it is the Transmission Range Sensor Switch part # 4L3Z 7E440 AB . After this, I am going to tackle the Blend Door. (This door stopped working several years ago. I just got the improved door from Dorman). Thanks again for your help. I will keep you posted on my findings.
RC

Originally Posted by DIYer...

First off... THANK YOU for this post. I followed your advice on replacing the solenoids because they weren't clicking. After replacing both, they still didn't click. I have power to both of them and the SOTF switch also has power but nothing happens when i turn the switch. Is it possible that the 4x4 switch is broken? Otherwise, maybe there is a wiring problem from the switch to the GEM or from the GEM to the solenoids?

Any one else have problems with this?

(Nothing at all happens when i turn the switch, no light, no click in the solenoids, no change in vacuum)

Thank you

Originally Posted by Ewlsu

Hey guys I'm new here !!! I have a 2000 ford f150 4×4 and I need help!!! When it's raining or I wash it it runs horrible, also when dry and I put it in gear it dies if I don't give it a bit of gas ! And as well it spits out a manufacturer code any suggestions

Originally Posted by Peckerpage

I have a 1997 ford f150 my 4x4 is not working. 4x4 light dose not come on when I turn the switch to 4hi or 4 low . I have removed the actuator in the transfer case and put it in 2hi by hand but as soon as I turn the key on the transfer case goes back in 4hi again. l have changed gem, switch, vac actuator on firewall transfer case actuator and still nothing. Front diff is not engaged but it does work I have engaged it manually. I really need some help I'm starting to lose my mind thanks

Originally Posted by Rob_Schu

Problem solved
I replaced the interior fuse box and the gem module with used ones I picked up from a salvage yard. 4wd is working again. There were some very small signs of corrosion on both units.