I was out of town and left my car at home for about three weeks. Upon returning home, I started my 2001 Mitsubishi Galant ES (4 cyl, automatic transmission)
and the check engine light came on. The vehicle tends to rev at around 2500 to 3000 rpm before the car moves and does not get out of third gear. I took it to auto-zone and plugged in the engine code scanner. It stated "P0715 Input/Turbine Speed Sensor, A Circuit Malfunction." I'm in need of any help which can remedy this problem.

MALFUNCTIONING
ITEM
JUDGEMENT
CONDITION
CONTROL CONTENTS DURING MALFUNCTION
Input shaft speed sensor No output pulse from the
input shaft speed sensor is
detected for one second or
more when the vehicle
speed is 30 km/h (19 mph)
or more.
The diagnostic trouble code is displayed when the
judgement condition occurs once. When the judgement
condition is met four times, the transaxle holds
3rd gear or 2nd gear depending on speed as a failsafe.
Output shaft speed sensor
Output from the output
shaft speed sensor is continuously
50 % or less of
the output from the vehicle
speed sensor one second
or more when the vehicle
speed is 30 km/h (19 mph)
or more.
The diagnostic trouble code is displayed when the
judgement condition occurs once. When the judgement
condition is met four times, the transaxle holds
3rd gear or 2nd gear depending on speed as a failsafe

hi, im having the exact problem...may i ask, what happend to the car>? and how did you fix it?

thanks,
- ilovemygalant

Some squirrels chewed my sensor wiring harness off of the top of the transmission right below the battery platform (acorns everywhere). This cause the transmission to jerk into second gear. Check engine light came on. Once seeing the bare copper, I went to Wal-Mart and got a wire splice kit. An hour of splicing later, everything worked fine and the check engine light went off.
I'm going to have to re-inspect my splice job. When driving on a downhill grade matching transmission speed with the momentum caused by the downward slope is causing my transmission to sporadically slip from 3rd to 4th.