[AdamAnt316]

Originally Posted by MadMan

I read that, and most of the problems were electronic. Gotta remember, the A604 was an entirely electronic transmission, with computer control on par with (better than some) today's cars - some THIRTY years later. 1989 was still really early for anything (let alone a complicated mechanical apparatus) to be completely computerized. Especially with an almost-AI that learns how you drive to adapt itself.

No wonder it had some teething problems. Regardless, it's a great transmission. I wish I could work on more of them, but they are starting to not be around anymore, the late 2000's was about the last of them.

I've heard multiple theories on what ails the A604. One is that using any transmission fluid besides Mopar ATF+3 (or +4?) is a very bad thing, unlike the earlier A413 3-speed which wouldn't implode if you used Dexron/Mercon. Several guides (like this one) imply that Dexron/Mercon is an analog for ATF+3, which apparently is not true for the A604. When I thought the transmission was going in my Spirit, I bought five quarts of ATF+3, which I gave to the local shop (along with a replacement filter) when I couldn't figure out how to drop the transmission pan myself to install said filter.

Another thing I found out about A604s is that sometimes they just glitch. One day, while driving home from college, I got on the highway and discovered that the transmission had dropped itself into "limp home mode", limiting me to first and second gear. After several harrowing miles with the engine screaming at 55MPH, I drove it directly to my local shop, expecting the worst. Instead, I ended up returning a few hours later to pick up the car, as the transmission was now shifting fine, and they couldn't figure out a cause for why it had dropped into limp-home mode.
-Adam