Hi, I have a 2000 F-150 auto with 4 wheel drive switch on dash. Sometimes it will not go into 4 wheel drive, doesn't matter whether it's moving or stopped. When it does work you can hear the relays under the dash clicking, and when it doesn't work those relays don't click. If I disconect the battery and then hook it back up it will always start to work again. Has anyone had problems with the generic electronoic module (GEM) ? Any input would be greatly appreciated.
Thanks in advance, Rick

 

There are quite a few GEM posts on the topic ( which I guess you already found, due to your question ), but if this is the only symptom I would not jump to a GEM problem.

When you have this problem, what is the indicator lamp on the ESOF switch ? Does it show the selection, or is it dead ( not even a 2H lamp ).

With the search you seem to have done, have you taken a look at the GEM ? Usually there would be signs of water on the firewall, carpet might be discolored, or the area around the Central junction box / GEM would have water marks.