My educational background is in computer science. I took my car to the dealer and they said that transmission fluid had leaked into the transmission control unit and the unit needs to be replaced.
Many people would just have the service done. The difference in the thoughtful approach is what questions you ask. How does transmission fluid leak upwards? (Capillary action through the electrical harness). Can the transmission control unit be repaired? (They said no, the answer is yes). What is the root cause of the problem? (They said "it happens sometimes").
If you stop to ask the questions and think about the answers, you realize that transmission fluid does not spontaneously leak twelve inches upwards in a functioning car. I had a mechanic find and replace a leaky bushing, clean out the transmission controller with electrical contact cleaner, and flush out the electrical harness, all for less than the cost of replacing the controller (which wouldn't have fixed the problem).
Many people would just have the service done. The difference in the thoughtful approach is what questions you ask. How does transmission fluid leak upwards? (Capillary action through the electrical harness). Can the transmission control unit be repaired? (They said no, the answer is yes). What is the root cause of the problem? (They said "it happens sometimes").
If you stop to ask the questions and think about the answers, you realize that transmission fluid does not spontaneously leak twelve inches upwards in a functioning car. I had a mechanic find and replace a leaky bushing, clean out the transmission controller with electrical contact cleaner, and flush out the electrical harness, all for less than the cost of replacing the controller (which wouldn't have fixed the problem).