Several months ago I was experiencing hard shifts and rumbling at low speeds. My car currently has about 88K miles. I did a lot of research on the internet and came up with several possible causes. I decided to remove the valve body, completely disassemble, clean, and replace the following:
1. New conductor plate and adapter plug
2. Replaced all solenoids with re-manufactured parts
3. Installed aftermarket valve sleeve kits
4. and of course new filter, pan seal, and fluid
Torqued all bolts to factory spec and reassembled. refilled the fluid step by step and everything was perfect until I shut the ignition off and the trans puked up a puddle of trans fluid and coolant.

So no big deal, I bought a new radiator and had it in and running in less than 45 minutes. The car has run like new for the last few months and all of a sudden the hard shifts and rumbling is back. I'll add at this point I share this car with my wife and we have very different driving styles. So today I drove it to get up to temperature checked the fluid level and it was dead on. I have a DAS (not an advanced user but can do basics) connected it and ran a diagnostic, to my surprise there were no faults. I decided at this point to reset the adaptions. I disconnected and drove the car and once again runs good as new.

My question is: is it possible the TCU is going bad, maybe do to the two very different driving styles and the age of the vehicle? or is there something else I am missing that would cause this.

Thank you in advance any help.


What can happened and may have happened in your case is that coolant and transmission oil have mixed together. If coolant gets into the trans it will destroyed it within a few thousands miles. Yes you will not get any codes, until the car stops moving. 

If it was my car I would take a sample of transmission fluid and test it for glycol which is found in coolant. There are plenty of labs that you can send samples to. One that I have used is Blackstone. 

You should also check the 13pin connector at the side of transmission for oil contamination. Easy fix.

Plain text

  • Allowed HTML tags: <a href hreflang> <em> <strong> <cite> <blockquote cite> <code> <ul type> <ol start type='1 A I'> <li> <dl> <dt> <dd> <h2 id='jump-*'> <h3 id> <h4 id> <h5 id> <h6 id>
  • No HTML tags allowed.
  • Lines and paragraphs break automatically.
  • Only images hosted on this site may be used in <img> tags.
The content of this field is kept private and will not be shown publicly.

Disclaimer: Youcanic has made every effort to assure the accuracy of the information on this page. Neither Youcanic nor its affiliates assume responsibility for any loss or damage due to any errors, omissions, lack of information. You agree to hold Youcanic free from any liability arising out of the use of any information contained within. All pictures and references to trademarks and car names are for reference only and do not imply an association with the manufacturer. Consult your owner's manual or authorized factory manuals when performing repair procedures. By entering this site, you agree to our Terms & Conditions and Privacy Polity.