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These recommendations do not cover all possibilities. They are some things to check before you have your transmission rebuilt. Always check transmission fluid level first. Always run a scanner on any computer controlled transmission. On modulated transmissions make sure they have enough vacuum.

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F4A / KM SERIES TRANSMISSIONS
The transmissions above are front wheel drive 3 & 4 speed automatic transmissions. They are computer and throttle pressure controlled.  Common symptoms are transmission shifting erratic, slipping or not shifting at all. Also the check engine light can come on.

External sensors like the throttle position sensor, vehicle speed sensor, output speed sensor and inhibitor switch quite often go bad, causing these symptoms. Check the throttle pressure cable that goes from your transmission to your carburetor or throttle body depending on the configuration of your engine. Always run a scanner first to see if a sensor is causing your problem.

Most of these style transmissions have sensors called pulse generators that plug into the top of the transmission. Two things can happen, the sensors can go bad, or a lot of people mix up the two sensor wire connectors by not marking them. They plug them in wrong, because they look identical. These two things can cause the transmission not to shift. Keep this in mind.

There are many variations to these transmissions. Many of the units above have an transaxle identification number located on the fender shield in the engine compartment. The transaxle case housing usually has a identification number located on it also. 

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