1996 Isuzu Rodeo speedometer quit working

1996 Isuzu Rodeo 3.2L V6 mileage: 65,000. My wife was driving her '96 Rodeo 3.2L V6 and the speedometer quit working. Oddly enough, the CHECK ENGINE light came on about 2 minutes later. When she restarted the CHECK ENGINE indicator came on immediately. I pulled the ECM fuse to reset the computer and drove the car for a few minutes. The CHECK ENGINE light did not come on, but the speedometer still doesn't work. Should I be thinking loose connection (already looked and didn't find any), faulty ECM, or the unlikely coincidence of speedometer failure combined with failure of another component that would trigger CHECK ENGINE?