Civic 97 EX Keyless Need Reprograming?

I swapped the engine for a newer one and now keyless disabled. Engine swapped was exactly the same and was just dropped in. No need to rewire, replace harness or add/delete connections.
I understand that the brain for this keyless is in the OEM radio which I can't find anymore. Do you need absolutely OEM radio or there's another way? Don't want to find an old 97 EX radio just to reprogram the keyless.

The keyless worked for more than "six years" with an aftermarket Sony radio. For six years there was no OEM radio left connected in the car and it worked fine with ONLY the Sony radio. Furthermore I have disconnected that battery for many other service jobs and it was all fine. From the engine swap I understand the radio lost all memories but it should not be able to "brain" the keyless since it is a Sony.
Logical reasoning conclusion is to deduct that there's another "Brain" since the Sony could not have for all the years.
Worse comes to worse, I will find an OEM 97 EX radio but I know for a fact the Keyless worked fine for six years without the old Honda radio still connected and hidden somewhere in the car.

Anyone? Anyone?
Thank you for any "Input" in this logical mystery. Really any input. The fix is easy with the old radio but my brain does not function that way.

I'm afraid so. You'll have to find any original radio re-connected to the car in order to program the remotes. The keyless entry works off of a radio signal that it sends to the control unit for the keyless entry but on that year Civic the programming is done through the valet/disarm button on the original radio. If the original radio was replaced because it didn't work (won't turn on) then you're out of luck with the remote programming unless you can find another original radio to do this with.

That's make me wonder the old unit should be in the dash somewhere, unless the Civic has an after market remote start system, the installer who is a pro will bypassed the old unit and make it worked. So back tracing your work on the wiring itself.

This is the procedure to program the remotes using any of the original radio.

Programming the Transmitter
Notes:
- The system accepts up to four transmitters. Do all, the one left out will not work after programming end.
- Entering the programming mode cancels all learned transmitter codes, so none of the previously
programmed transmitters will work. You must reprogram all the transmitters once you're in the
programming mode.

1. Turn the ignition switch to ON (II).

2. Press and hold the Valet-Disarm button on the radio (between the AM/FM and CD/TAPE buttons) to
enter the programming mode. Continue to hold the button during this procedure, or programming will be cancelled. The power door locks will cycle to confirm that you're in the programming mode.

3. Within 5 seconds, press the "Lock" or "Unlock" button on the transmitter. Check that the power door locks cycle to confirm that the code was accepted.

4. Within 10 seconds, press the "Lock" or "Unlock" button on each of the remaining transmitters.

5. After all the transmitters have been programmed, release the Valet-Disarm button to exit programming mode.

Can you borrow any original radio from friends or from somewhere? If you have to buy one (It's cheap) then just use this harness adapter, most people leave the remote connector plugged into the stock radio and tuck it behind the new radio (hiding the old radio in the dash) this will allow you to keep factory keyless entry:

http://www.ebay.com/...0139093962

If no original radio found, try these sites: Very informative information, just do your reading then ask the question(s):

http://www.the12volt.com/
http://www.installdr.com/

Edit: I heard people can do it without the original unit by using the door switch for the dome light, I never asked them how to do it. Sorry.

Thanks my friend "liverhuyen2003".
This is the best answer ever.
I only want to reiterate that I did the engine swapped and the installation of the Sony radio, seven bands Kenwood EQ, four channel amp, 1800watts Kenwood Class "D" sub amp and two 12" Kicker Pro and know every inch of this car I' ve had for the last 11 yrs. No Hidden OEM radio and Keyless worked fine last 10yrs until swap without it. (Had to rip seats, floor and half of the dash for this)

I can find one OEM but thinking at this point now, may install antitheft system and forget about Honda keyless.

Again, thanks so much I will save all this great info on how to program Honda keyless and wish you great day/rest of the week man.
Love the exact & precise directives to the programming.