Hard downshift but on 5R55S

[Phantom]

Just noticed hard downshift when nearing a stop as I very rarely drive it. I found the TSBs for the 6 speed tranny but didn't see one for the 5 speed, or just missed it. The symptoms are basically the same, a clunk or thud just prior to stopping. Any help is appreciated.

 

[Flag Gibby]

How many miles on the vehicle and when was the last time the tranny was serviced?

 

[Phantom]

It had 99,000 when a new transmission was put in just before I bought it. Mileage now is about 145,000 so it is due for service.

 

[Flag Gibby]

Okay, definitely start with a fluid change and then if that doesn't fix it I would start looking at other possibilities. Make sure that the correct fluid is used for the transmission when it gets changed. FYI, at 145k you are due for a new PCV valve if it has not been changed yet as a part of basic maintenance.

 

[Phantom]

Any idea if there were any PCM updates for the 5R55S like there was for the 6R60? PCV and all other normal tune-up/maintenance times have been done. Thanks.

 

[Flag Gibby]

There have been some minor tweaks for the 5 speed, but nothing for a hard downshift like the six speed.