Transcript:
In some cases transmissions are replaced when the problem is not actually in the transmission. Instead the malfunction could be caused by an external sensor, solenoid, or engine miss fire.
Prior to removing the transmission it is essential to perform an accurate diagnosis. Always connect a diagnostics scan tool to the vehicle to look for a diagnostic trouble codes. If codes do exist research exactly what they mean. In addition monitor the vehicles parameters to ensure that they are reading correctly.
For example a manual level position sensor, or MLPS, can cause erratic shifting if parameters are not reading correctly.
The next step is to perform a voltage system check to ensure the battery voltage is correct, as well as all grounds, this includes battery, computer, and body grounds.
Finally check the level and condition of the fluid to ensure that the level is correct, and verify the condition of the fluid. Pull the transmission dip stick out, wipe it off, and insert it back in the tube. Now remove it again and check the dip stick. Be sure to check both sides of the dip stick. The lower side is your correct reading.
If everything checks out ok externally you can feel confident in your diagnosis that the problem is inside your transmission.