[dirtymazda]

Originally Posted by gromittoo

I believe the 2002 has the computer controlled transmission. If it does, then the TCM could have decided to put itself into "LIMP MODE". The TCM may decide that it can't trust the inputs it is reading, and Limp mode prevents it from destroying itself. Most code readers won't see that code, you may have to go to a dealer to read that code.

I had the same issue with a 2001 minivan which has a simular transmission. I had a weak battery, and I had left the doors open. The battery got so drained, I could not even jumpstart the van. I got a neghbor to jump it with a 200 AMP starter / Charger. After driving on the highway for 15 minutes, the van abruptly downshifted. I drove it to a Sears. After waiting 4 hours, they found nothing wrong.

I continued my trip, and the problem came back 15 minutes later. I eventually realized that I could reset the TCM every time I turned off and restarted the van. After a few hundred miles, the problem went away.

I think the very low battery voltage caused the TCM's lookup tables in its internal memory to get corrupted. After driving a few hundred miles, the TCM re-learned the data.

is there anyway to reset the tcm without driving it? this happened a few months ago and since i put maybe 100 miles on the car and no change. it had a brand new battery in it.