My '96 powerstroke is having ISSUES. First off, the E4OD transmission was just rebuilt after deciding it didn't want to go forward. Apparently some gear cylinder had a hairline crack. The garage I was dealing with removed the transmission, then it went to a specialty rebuild center, then the garage put it back in. They didn't do the tranny work, in other words.
Anyway, as I'm picking up the car, I drive it down the road and immediately notice that the speedometer is freaking out--it is jiggling back and forth, in about a 20mph range, with the bottom-middle range being about where the actual speed probably is. I promptly turned around and went back to the garage. I figured the speedometer cable was loose, and found out that it isn't a cable, but a sensor on the rear differential. They said they didn't have a sensor in stock, but that it should solve the problem, and wasn't related to the transmission work. I bought that, sounded plausible to me.
I headed home from the shop, as I didn't have the option of leaving it there-I needed the truck! I just was careful with my speed and went pretty slow. I realized that the tranny was having issues keeping itself in 3rd/4th/overdrive in between 35-45mph. The VSS (variable speed sensor) problem really made sense to me, and sounded like it was the issue, as it seems that it controls the OD function of the tranny??? (I've read that somewhere here on this site). At some point the next day, as I have to get a load of firewood or risk being cold this winter, I realized that when I pushed the trip odometer button, the problem seemed to instantly vanish. The transmission shifted fine, stayed in the right gear, speedometer was smooth. Then, a couple days later, same deal. Dancing speedometer. Same fix, except that the next time it happened, the third or fourth time, the odometer button didn't seem to fix it.
I bought a new VSS and installed it; no change in the problem. I also dismantled the dash and checked that the connections were all tight as best as I am able to check-nothing is loose or obviously disconnected. I had changed some light bulbs a while back and thought that I might have loosened something, but everything appears normal. The guy at the shop where I got the part said their shop truck, a GMC, does the same thing, and it has a motorized speedometer, not unlike the Powerstroke Ford. It is clear to see when you have the dash apart and look at the circuit board.
So now I'm confused about what I do now?? Will replacing the whole gauge cluster reset my odometer ?? Not doing anything isn't an option, due to the tranny shifting funny when the speedometer is between 35-45mph. What kind of electrical problem am I missing???