1997 Ford Explorer XLT Generic Electronic Module

I am having trouble with my 4WD as follows: Upon starting the vehicle the 4WD is engaged and cannot be turned off. The 4WD dash warning lights flash intermittently. I have traced the problem to what the Haynes Manual calls the "Generic Electronic Module". However, I cannot find a replacement part on the web. Is the part called something else. Any help would be appreciated.