4WD problem - getting desperate

I've got a '99 Passport, automatic SOTF 4WD, about 90K miles. It started to spontaneously shift into 4WD, mostly when slowing down. A high pitched grinding noise starts near the front passenger side and the 4WD indicator light begins blinking, like it is trying to engage. The only way to get it to stop is to push the auto 4WD button, let it ride in 4WD drive for a moment, then shift back out.

The Honda dealer cannot figure it out. They've already replaced the SOTF motor and solenoids, and have spent numerous days now driving it around and calling the Isuzu dealer. Nobody's heard of this problem.

I've had luck in the past reading the threads on this site...was hoping somebody out there might have an idea. Help!!

Sounds like a bad switch or relay. Just a suggestion.

thanks. dealer just called and said it was a switch.