bad odometer/speedo after tranny fluid change

[sparks]

This is a weird one. I changed my tranny fluid and replaced the filter about a week ago. The first time I turned on the truck the odometer started rolling forward and the speedometer started going up when I was parked. It seemed to calm down for a couple of days, but today it was acting really weird. The odometer was going forward and backwards, and the speedometer is way off. I guess if the odometer was going backwards the whole time I might not mind as much. I filled my tranny fluid a bit to high and blew it buy not putting in a cover with a drain bolt. I've been to lazy to drain some back out. Other than that, it seems to run pretty good. I was wondering if anyone had seen something like this one before.

[daredevil350]

In theory your problem is possible, the speedo is a magnetic/electric sensor rather than actual gears. So if you have an open wire/sensor you could see this problem, fluid level will not affect this though. Check your wires for any obvious faults, check the sensor, disconnect the battery for awhile. Pull the speedo sensor out of the drivers side of tranny, 10 mm bolt, clean it and re-install.

[robertfoster]

Does the needle drop back to zero if you hold the engine speed at 1500 or 2000 rpm?