1989 TBI 350 swapped in place of 1989 TBI 454- IAC wiring & ESC/knock sensor question

**lionelhutz** · 05-12-2015

I think the TH400 downshift solenoid and the 700R4 converter lockup use the same PCM output.

**Mr. Bowtie** · 05-12-2015

Originally Posted by lionelhutz

I think the TH400 downshift solenoid and the 700R4 converter lockup use the same PCM output.

So I can swap ECM's? I'm not sure that they are interchangeable like that because of the engine programming.
Thanks again.

**lionelhutz** · 05-13-2015

You could do that and fix the transmissions but then the engines won't run right. Does one vehicle have a 700R4 and the other have a TH400 or not? If you answer yes, you have to either find the right chip or do some programming to fix it.

**Mr. Bowtie** · 05-13-2015

Thank you for your reply. That is exactly what my fear issio I figured that I had nothing to lose so I put the original ECM back in & ran it. Shift problem is resolved & it appears to run perfectly. I didn't run it at WOT however. Maybe I'll do that tomorrow. The big thing I was concerned about is over or under fueling. I guess I'll see tomorrow. Thank you for your input & help. I'll update as to what I find.