C70 Auto Tranny

dfrenzy2 · Post by **dfrenzy2** » 06 Oct 2016, 20:02

Hi, my 2002/3 C70 tranny is fine for a while, but when it heats up in traffic, stop start etc. it starts to clunk, search for gears, and stops talking to the EMS...I believe there are temp and engine speed sensors on the tranny wiring loom, could this be the problem?? When the tranny has cooled, it works fine again for a while..any feedback is welcome, Thanks

Post by **cuhfs** » 07 Oct 2016, 11:24

Does car stop moving completely once it heats up? How do you know it stops talking to the EMS? How many miles on car?

Post by **kahl** » 07 Oct 2016, 14:17

I would first evaluate the level and condition of your transmission fluid. Is level correct? Color of fluid. When was the last time it was changed?

Post by **precopster** » 07 Oct 2016, 14:54

If the problem's totally not there when cold then fitting a transmission cooler would be the way to go. These AW55-50s suffer from poor solenoid valve clearances in the SLT, SLU & SLS solenoids when they warm up. One solution is to open up the valve body and re-clearance them. Trans Go have a kit for this that costs about $140. This is a large project because it means partially dropping the subframe.

The fluid temp sensor is located in the valve body behind the cover and both speed sensors are on top of the transmission. Without codes from a garage reader or from Vida-Dice I wouldn't be looking at sensors if I were you.

As mentioned fluid can be contaminated. Drain and fill over to a quality synthetic JWS-3309 compliant one and that may help somewhat.