Gerhard

I've noticed that the original post on the EFI forums no longer exists.

So, if you are swapping from a 5th Gen Auto to a Manual transmission, you have two options:

1) Install an ECU from the same model year car as yours, and make sure you have a key for the imobilizer unit [There have been many discussions of this over the years, but basically, there is at least a 50% chance that you can not simply put in a new ECU from an another Prelude and be able to start the car].

2) Take out your ECU and the TCM, then simply convert your ECU by taking the Auto P5M from your 5th Gen and changing it to Manual operation by moving the RP13 000 Ohm resistor (jumper basically) to RP14.

[You need a fine soldering iron to do this...]

This will remove the communication to the TCM module (or at least the expectation from the ECU that it should be getting a signal from the TCM) and the car will not longer experience a rolling idle.

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Allude2Prelude9

There is a thread on Honda-Tech about this. The English is a bit hard to follow so I rewrote it here.

Auto to manual ECU conversion:

1. Disconnect the battery, negative terminal first.
2. Locate the ECU. It's underneath the rug under the passengers feet.
3. The Ecu is underneath a protective cover, which has 4 10mm nuts holding it in place. You will need to use a 10mm deep socket to remove it.
4. Unplug the harness.
5. Unbolt the Ecu from it's protective cover.
6. Remove the cover/lid from both sides of the ECU.
7. Locate the 000 resistor that is labeled RP13.
8. In addition, locate the target area RP14 on the other side of the circuit board.
9. Very carefully de-solder the resistor from RP13. Use tweezers or a small screwdriver to remove it while the solder on both ends is melted.
10. After successfully removing the 000 resistor from RP13, flip the board over and place it on the RP14 spot.
11. Re-solder both ends of the resistor.
12. Screw every thing back together in the reverse order of removal.
13. Put the ECU back in the car and reconnect the battery.
14. Start the car, everything should be good.

You do not need to keep the TCM connected or in the car after this. I would secure the end of this harness so it doesn't bounce around and make noise while driving.

pIERCE

Resource resource resource.

Gerhard

I've added the pictured to the thread.