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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 first. On modulated transmissions make sure they have enough vacuum.

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A340H
The transmission above is a rear wheel drive 4 speed automatic transmission. It's 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 or output speed sensor 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. On most of these models, they have a diagnostic box you can retrieve codes with. The location of this box should be in your owners manual.

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4L60E / 4L80E 
The transmissions above are rear wheel drive 4 speed automatics that are all computer controlled. Common problems are: Check engine light comes on. The transmission shifts erratically, slips or does not shift at all.

These problems can be caused when the external sensors on the vehicle go bad. The input and output speed sensors, throttle position sensor or vehicle speed sensors need to be checked. Always run a scanner first to see if a sensor is causing your problem.

 An ignition switch that goes bad can cause a false shift solenoid code that comes up on a scanner. So be careful.

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A40 / A44DL 
The transmissions above are rear wheel drive 4 speed automatics and shift timing is controlled by the computer and a throttle pressure cable that connects from the transmission to the carburetor or throttle body.  

Always check these items first before your purchase a transmission. Common symptoms are transmission shifting erratic, slipping or not shifting at all. Also the check engine light can come on.
On most Toyotas, they have a diagnostic box you can retrieve codes with. The location of this box should be in your owners manual.

Make sure your clutch fan on the front of the motor is not starting to seize up. This causes the engine to sound unusually loud almost like the transmission is not shifting into 4th gear.

 

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200C
This transmission is a rear wheel drive, 3 speed automatic.  Common problems are: The transmission shifts early and soft. It shifts late and hard. It does not shift at all.

Always check the throttle pressure cable that goes from your transmission to your carburetor or throttle body depending on the configuration of your engine. This controls the shift points and sometimes the heat causes the little plastic connector that holds it on to become brittle and break, causing erratic shifting.

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MPJA / MDWA
The transmissions above are front wheel drive 4 speed automatic transmissions. They are computer and throttle pressure controlled.  Common symptoms are transmission shifting erratic, slipping or not shifting at all.

External sensors like the throttle position sensor, vehicle speed sensor or output speed sensor quite often go bad, causing these symptoms. Always run a scanner first to see if a sensor is causing your problem. Check the shift solenoids that attach to the transmission casing, sometimes they can go bad.

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JR403E / JF403E
The transmission above is a rear wheel drive 4 speed automatic transmission. It's 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 or output speed sensor quite often go bad, causing these symptoms. Always run a scanner first to see if a sensor is causing your problem. Check the throttle pressure cable adjustment that goes from your transmission to your throttle pedal under the dash.

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4L30E
The transmission above is a rear wheel drive 4 speed automatic, that is all computer controlled. It uses a microcomputer to judge operating conditions while monitoring the throttle position sensor and vehicle speed sensor and many others. 

Common symptoms are trans shifting erratic, slipping or not shifting at all. external sensors on the vehicle like the winter mode switch, throttle position sensor and vehicle speed sensor, quite often go bad causing these symptoms.

Always run a scanner first to see if a sensor is causing your problem. I recommend that you change the transmission fluid on this style transmission about every 12,000 to 15,000 miles.

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F3A
This transmission is a front wheel drive 3 speed automatic. Common symptoms are erratic shifting, hesitating going into gear and losing transmission fluid without a trace of a leak. 

You have a modulator on this style transmission. Pull the rubber line off the modulator and see it trans fluid comes out of the line.  Now, if it does your modulator is no good. It can cause any of the above symptoms.

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