A518- A500 Transmission control question

I have a 1990 B350 Van with a 360 and 4 speed auto,(Not sure what model as of yet.) I had a problem with the ECM and changed it out with one from a 1990 Dodge W250 with a 4 speed Manual Transmission.. The van started right up and shifted fine, just wouldn't go into overdrive. So I took it for a drive yesterday,I have no reverse, and it wont coast in neutral.. Would this have anything to do with changing the ECM? As I said the one I replaced it with was from a Manual Trans Truck, so Im figuring it has no transmission control capability since it was from a manual truck.. It may be a coincidence that it happened not long after changing ECM.. What are your thoughts? Thanks

Yes, a manual trans ECU will not play well with an auto that needs the ECU to control the OD and torque converter lockup.

On a 1990 all the computer controls is overdrive and possibly lockup. 1st-3rd and reverse are still hydraulically controlled, exactly the same as a 727 or 904. It would run the 3 gears forward and reverse with no computer at all. You have bigger problems.

Might be in limp mode because of the mismatched ecm.

You can order the correct ECM from Solo Electronics in Florida.

Does it try to drive forward in Neutral and lurch forward in Park?

1990 is not computer controlled with the exception of OD and the converter clutch.
Unplug the connector at the trans and see if you still lose reverse. If so, its in the trans.

Pat

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Does it try to drive forward in Neutral and lurch forward in Park?

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Yes! That's exactly what it's doing John