QuestionJust got my 99 elantra tranny rebuilt a week ago, and car was fine. But now the reverse has all but stopped working. When it will go into reverse, the car lurches abruptly, and goes sporadically. It also shows these symptoms in first gear, though not as bad. Mechanic says this is a electrical/computer issue, not a transmission issue at this point. This makes no sense to me. They are saying the next step would be to replace the computer, as all the sensors are new. Is this a possibility? I can't believe a computer makes the car go into first or reverse...
AnswerThe transmission in your vehicle is indeed computer controlled. A complete diagnosis will need to be done to determine for certain whether the issue is computer related or in the transmission. This should be possible with a scan tool that will read all the data from the transmission computer.
The logic of the mechanic's diagnosis is a little flawed, however. Just because the transmission had been overhauled and all the sensors are new (which they probably aren't), that doesn't indicate that the problem is in the TCM.
For what it's worth, it's my gut instinct that the problem is within the transmission. But I don't have much to go on other than my experience with the various causes in the cases I've seen and the horror stories I've heard from people that have had their transmissions rebuilt.
You car was fine for a week, and now the transmission isn't working properly. What makes the mechanic so sure that the problem is the TCM? What diagnosis did he do to determine that was the case? What reason is there to believe that the issue isn't in the transmission? Since he rebuilt the transmission and it's not fixed, shouldn't he be providing warranty service?
How about this as a suggestion. The mechanic gets the computer and puts it in the car. If it fixes the car, you pay for it. If it doesn't, he pays for it, he finds the real problem, and he fixes it under warranty since it was something that wasn't fixed right to begin with.
