I have 97 F- 150 4X4 with 5.4L engine and have a problem with the transmission not shifting properly and no speedpmeter while drinving in heavy rain . After truck sits for at least a day truck transmission and speedpmeter is normal. Has any one had this happen to them? I have hadthe truck in shop and replaced the VSS sensor on transmission and rear axle speed sensor.
Thanks for any suggestions.

 

FWIW....As I recall sometime ago reports were water leaking into cab & caused lots of problems. Try checking under dash w/flashlight when its raining.

If not raining, use a hose to spray water across windshield etc. Best if two people do this. One sprays/one inside looking. Look for updates. Also try "search". Seems water also caused problems w/gem module, but dont recall what they were.

Good luck on the fix. OT

 

I did see their was a service announcement on the gem module . Where does this module mount on the vehicle ? Does this control any thing with the speeometer or transmission? Thanks Terry

 

T

On second thought, forget about GEM. I think thats for shifting/4WD, which is not your problem.

Did you try posting on tranny bd? Ask about the wiring harness to tranny. Its electrical & bad connection etc. causes problems. Sorry, I dont know for sure.

Good luck on fix. OT

 

I had the very same problem on my 97 4.6L. truck would stay running when turned off, Speedo quit, overdrive lights flash, and more....
Took it to the dealer, they replaced the Gem box....(fuse panel under dash)

Come to find out, my windshield had a small crack and allowed water to leak directly on the panel, so I replaced that also and problem fixed.

 

Correction...GEM stands for Generic Electronic Module and has everything to do with it...it's the electrical nerve center for your vehicle, not just for 4-wheel drive...

 

The windshield crack you refered to was this a factory defect? I had the same problem today , but this time after normal driving and during light rain. I had eariler to day took the truck thru heavy rain and lots of water on roadway no problem then.
Thanks for you reply it gives me a start . I think I will replace the Gem module that you also replaced. Oh yea my brother in law is having the same problem(he has 98 4.6L) I will relay the information that you gave me to him Thanks again. Terrry