Automatic transmission wont shift unless battery disconnected 2006 fwd 2.5

racertim · Post by **racertim** » 08 Mar 2019, 10:08

It was suggested that I post in the s60 forum since drive trains are the same as my XC90. Here is my post: I have a 2006 XC90 fwd 2.5t with 150K. Long story needed to have engine replaced. Local mechanic shop (son-in-law but that's another long story) replaced engine with a good used one. Took him forever to get it done so car sat for months at a time. Finally done, engine runs great BUT when you shift it into Drive, it will go forward and shift through the gears. When you come to a stop and want to put it into reverse it will not go into reverse. If you disconnect the battery and then reconnect it, it will then shift into reverse. Same story going back into drive. You have to disconnect the battery and reconnect and then it will shift into drive. So he takes it to local AMCO shop to look at it. All they can say is that the transmission needs rebuilt. The transmission worked flawlessly before the engine was replaced. I am thinking so did they not hook up a wire correctly or what? I find it hard to believe that it was working great before the change out and now it just isn't. I called the local European Motors shop and they said $3000 to replace the transmission with a used transmission. But I am not convinced that is the issue. Does anyone have any advice on how to diagnose what might be happening? The car is in great cosmetic shape, but need to get the mechanical stuff right!
Thanks!

Post by **xHeart** » 08 Mar 2019, 11:53

racertim wrote: ↑08 Mar 2019, 10:08 ... engine runs great BUT when you shift it into Drive, it will go forward and shift through the gears. When you come to a stop and want to put it into reverse it will not go into reverse. If you disconnect the battery and then reconnect it, it will then shift into reverse. Same story going back into drive. You have to disconnect the battery and reconnect and then it will shift into drive. [...]

Does anyone have any advice on how to diagnose what might be happening? The car is in great cosmetic shape, but need to get the mechanical stuff right!
Thanks!

I had similar issues after 3 weeks of unplugged battery due to maintenance and repair.

To help get started. What is the age of fluid, level, and make?

racertim · Post by **racertim** » 08 Mar 2019, 12:12

Haven't touched the fluid since before the engine change-out. Only checked the level.

Post by **xHeart** » 08 Mar 2019, 12:58

Unless you're certain it is an electrical issue, fluid change is a good first step. Mobil ATF 3309 works for AW55-xx transmissions.

IslandV70 · Post by **IslandV70** » 08 Mar 2019, 14:49

Doesn't this sound more like software than fluid?????????

Post by **xHeart** » 09 Mar 2019, 07:17

It does. There could be any number of things.

In our situation, a FULLY charged battery and several drive cycles brought gear shifting back to normal. ATF getting HOT is important for transmission adaptation.

Any stored DTCs?

Some variables viewtopic.php?f=9&t=75828&start=30

racertim · Post by **racertim** » 09 Mar 2019, 07:21

No codes

IslandV70 · Post by **IslandV70** » 09 Mar 2019, 07:58

My car went into a mode where it would barely drive due to a low battery. Just driving it and restarting it fixed it.

racertim · Post by **racertim** » 09 Mar 2019, 09:15

I put a new battery in, no change

IslandV70 · Post by **IslandV70** » 09 Mar 2019, 09:22

I think you need VIDA to see what is what.