Granddaughter just bought my nephews 2010 Mazda 3 wagon, he got rid of it because AT light came on and not shifting. Dealership said it had communication codes to trans stored, they sent TCM off because could not get one but that did not fix it, said it needed transmission. Been parked for a year, son-in-law said when cold it goes into gear and shifts up to 5th gear then down ****s to lower gear after AT light comes on. Turn car off and it will manually shift into all gears then let off an AT light comes on and it down shifts to a lower gear but keeps on moving just to higher RPM, any suggestions

 

Welcome ot the forum
Take it to a specialized transmission service shop.

Do not replace any parts before they have shown to have failed. Nothing showed me that the diagnostic was done correctly and there was an assumption (GUESS) to have the TCM rebuilt???

When was the last transmission service done and what was it before the transmission started to have problems?

If you don't know and no one kept service records then expect you are going to get an estimate for a rebuilt transmission.


BTW you already started one thread about this problem I posed in it and copied and paste for this thread same responses. LOL