98 Odyssey with Check Engine On Computer / PCM failure code; desperately seeking advice!

My 98 Odyssey with 105k miles needs to get a clean emissions bill in the next 30 days or my registration gets suspended. The problem is that the computer is throwing a P1607 code for a general PCM or
computer failure. I would like to avoid buying a new (or used) PCM until I can be reasonably certain that that will fix the problem. Anyone know if either: 1. I can swqap out my parents' PCM from their 97 Accord to see if it fixes my problem?, OR 2. where on the web to buy an inexpensive PCM unit and how to know which part my particular vehicle needs?, OR 3. have any other ideas?
The background:
About a month ago I first started seeing an inconsistent transmission-related problem: occasionally the car goes into "limp home" mode (4th gear?) and I either have to drive it in low gear till I get to highway speed and put it back to D4, or pull over and turn the car off and then on again and the problem goes away. I brought it to a transmission guy who read both a torque converter problem code as well as the PCM failure code (P1607) and he recommended I see the dealer before making any tranny investments. I went to the dealer and they sold me an expensive tranny flush saying they thought my dirty fluid might have fouled a sensor. Dealer said not to be concerned about the PCM code (!)
So now I have to somehow clear the code and make sure it doesn't come back so I can at least have a registered vehicle in the good graces of the state DMV.
Any advice here would be appreciated! Thanks for your time!
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Wrecking yards are a good source of computers; I bought an ECU for my son's old Accord (flood damaged - water just barely touched the ECU and killed it) for $75 with a 30 day warranty. 30 days may not sound like much, but if it doesn't give you trouble in 30 days it probably never will.
Mike
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grassyhillatsymbolgmail wrote:

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Have you checked your invoice to see that the Honda dealer put Z! Honda ATF in your tranny when they were through? Honda trannies are NOT supposed to be 'power flushed' and only Honda Z1 should ever be put in them. I'd do a 4 quart drain-n-fill just to be sure. As for the PCM, I'd do like Michael said. Be sure to disconnect the battery :-(
BTW: Have you tried just resetting the thing by pulling the backup fuse (15 seconds) with the keys out?
'Curly'
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Thanks Curly Q. Links for the advice on resetting the PCM with the backup fuse. That may work, though I need to know how long I need to drive before the car returns to a state of "Readiness". Does anyone know? If I reset it, I have to drive some number of miles/amt of time or else when I go back to emissions they will see too many "Not Ready" readings.
I need to be sure that I clear it, drive it long enough to get it "ready", and go directly to emissions. My experience with this code being thrown is only when it's a completely cold engine.
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