OD off turned on by itself?

[94cummins]

Is there any condition the pcm can see that will shift the truck into OD off on its own? I was driving my truck, empty on flat ground, when the trans downshifted on its own. Creeped me out so I went to neutral and did a guage check and noticed the OD OFF light on. Trans temp 150, engine 160, boost 7, pyro 850, volts 14, oil pressure 40, nothing out of the ordinary. I just turned the OD OFF *off* and put it back in D and went on my way. It didn't do it again after that. I smacked, flicked, and generally messed around with the switch to see if it was flaky. Seems to be OK. Any ideas?

[Joe G.]

There is a grimlin in these things that does that. Nobody knows how to fix it either. It drops out of OD just for the hell of it. Might not do it again for a couple of years. Or it might do it again the next time you drive.