transmission problem

[Crvett69]

have a 91 geo metro with a automatic transmission issue. takes off in second gear?? and doesn't seem to up or downshift. you can take it up to about 30 mph and let up on gas, its like it goes into neutral and you have to rev the engine up quite a bit to get it to start going again. if you unplug the computer you can shift it manually into 1st, 2nd to 3rd and it works just fine so think tranny is good. i replaced the transmission computer and it does the same thing. all the printed numbers on the computer are the same and its supposed to be out off a 91 metro. the 4 digit stamped number on the tag is different, mine says 1D04 other one says 0I14 but rest of the numbers are the same. anyone run into a issue like this before or have any ideas?

[Woodie83]

The shift solenoids go bad all the time, plus, our cars (really, any 20 year old car) are notorious for bad grounds and bad connections. Lay 12 volts on the solenoids and see if you can hear it click. If not, check the resistance of the solenoid.

[Crvett69]

think i found the problem, speed sensor on top of the transmission has a open (no continuity). waiting for friend to snag one out of one of the cores and will see if that fixes it

[Woodie83]

That would have caused a check engine light with an error code 24.

[Crvett69]

speed sensor on top of tranny, not the one built into the speedometer

[91 ragtop]

Does this speed sensor go right in front on top of the transmission and plugs into the harness by the speedo cable ? If so I should have one. Ken....

[Crvett69]

my friend has about 6 core automatic so i think he has one he will give me but thanks for the offer

[Woodie83]

Manual transmission cars use the one in the speedometer, automatic cars use the one in the transmission. A problem with whichever one applies to your car will cause a 24 error.

[Crvett69]

car has no error codes, the transmission computer operates independant of the main computer in 91 and problems with it or auto tranny will not kick out any obdI codes. even with the sensor unhooked and no pulse still no codes. sensor tests open with no continuity so i know its bad, will start with replacing it before i look any further if it doesn't fix the problem

[Crvett69]

replaced the sensor and now car shifts like its supposed to. forgot how sluggish the automatics were but at least it works

[doug2060]

Mine went bad once too. I didn't throw a code either. It was a bit more obvious than your problem though. The needle was going crazy. Good luck with your metro.

[Woodie83]

Well, I'm horribly wrong then. Maybe it's just the OBD2 cars where the entire powertrain is controlled by one box.