Have an 89 manual ECM.  Want to install an auto.  I realize the loom will need some work but are the ECMs interchangeable?

With an 89, is this a Samurai or a Sidekick/Tracker?  You could switch to the Volvo automatic, since it does not require a separate TCM (Transmission Control Module).

You can run the auto ECM, the loom should be the same you'll just have to add any extra wiring to the trans and the lock up relay. If the loom is different then its no big deal as there are only a few wires to add.

Thanks all.  And Bret at TT says my manual ECM will work as long as I don't care if the lockup works.

I have read about people wiring up the lockup to a switch so they can turn it on while on the highway.

Thanks all.  And Bret at TT says my manual ECM will work as long as I don't care if the lockup works.

I guess you are putting in a 3 speed auto?  If so, then what Brent told you is correct.

Yep, should have said 3spd.