I have been researching the web looking for answers to my issue and they are all telling me different ways to fix the problem or what it could be.

When I am accelerating the transmission shifts normally no noise or thuds, but after the trans is up to operating temp the problem begins. Only when decelerating with normal use of the break, when I hit 35MPH there is a thud when the transmission down shifts. I am not showing any codes, the trans fluid is at its normal level, and is a healthy pink.

Im sorry if this is a repeat post but I was 9 pages in on searching transmission problems on this site and nothing helped. Guys Please Help!!

 

mine started doing that as well and i changed the plugs and it stopped. smoe how the plugs mess with the tranny

 

Possibly a speed sensor issue, input or output, or the brake interconnect.

What year, has it been serviced at all?

 

I just changed the plugs about 6 months ago and I do the service myself. Is a 2004 1500 Quad Cab.

 

Specifically I was asking if the tranny had ever been serviced, sorry it wasn't clear. Have you ever had the fluid & filters changed? Ever had a tranny related cel? What's your miliage at now?

 

Im not sure if the tranny has ever been serviced, I never did. The truck has 103,000 on it. Could the fluid and filters not being changed make a thud like hitting a pot hole. It always happens decelerating at exactly 35 MPH after the truck warms up.