I had a problem about a month ago while cruising on the highway at about 70mph with my overdrive. 4th gear completely died, and swapped into 3rd. A minute later, it hopped back into 4th. It repeated this several times, until I started going "what the hell is my car doing" and pushed the overdrive button. The overdrive light came on, and then began flickering -- at the same time that the overdrive gear was shutting on and off. Hence, something is telling the car that the overdrive switch is being pushed repeatedly I believe.

It popped out 2 engine codes. One was ECU was having trouble communicating with the transmission, and the second was Inhibitor switch. Someone in the thread mentioned that when their inhibitor switch went bad, they had the exact same symptoms I was having -- a flaky overdrive gear. I forked over the dough and changed the inhibitor switch the following weekend, and the problem went away....

Until today! It's come back, and it also did afew odder things that I thought were strange. Driving along, it started hiccuping, and then proceeded to drop into 3rd gear again. 3rd, 4th, 3rd, 4th, I pushed the overdrive switch, and it stayed only in 3rd. I was about an hour away from home at this time and was not thrilled that I would have to do the whole trip in 3rd gear. So I'm cruising along, and I push overdrive again, it pops back into 4th, and 2 minutes later, pops back into 3rd -- and stays put for a fair while. This is where the strange part comes in.

I notice the heat gauge says my car is 3/4 of the way up the gauge, and it's normally 1/2way through the gauge. I said "****, it's overheating, greaaaat." I immediately popped the air conditioning off, turned off the stereo and as I did this, 4th gear came back, AND the temperature shot immediately down to 1/2, where it's suppose to be.

This is the only time I've ever seen the temperature gauge go above half. Can a faulty thermostat in any way affect the overdrive switch? Or is it possible a loose connection on the overdrive button assembly itself can cause it to flip on and off at random? This problem is driving me nuts, and after finding out I spent $100US for nothing on the inhibitor switch, I'm really wanting to figure out what the hecks wrong with it. There are currently no engine and/or transmission codes. Help!