Gerhard

Ok, here is the deal:

The 5th Gen Prelude has several components to prevent the car from being hot wired and stolen.

The parts are:

1) The ICU (ignition control unit ). The ICU functions to read the stored code in the ignition keys and send that information to the ECU, enable the starter circuit, and the fuel pump.

2) The Black and Grey Keys . Each key from a Prelude has a code stored into it that can be assoicated with an ICU/ECU combo.

3) The Red Key . The Red key is a key specifically coded to a specific ICU. This key tells the ICU wipe the ECU's memory of currently acceptable car keys that are allowed to start the car, and to prepare to be reprogrammed.

4) The ECU (electronic control module - a.k.a. computer). The ECU is the car's brain. It also stores the key codes (eletronic tags embedded in each ignition key) that are premitted to start the car.

What does this mean to you when doing an SS Auto 5 Speed swap?

During a 5 speed swap you need to replace the SS Auto ECU with a 5 Speed BASE model computer (make sure you are getting a BASE model ECU and not an SH ECU!). Once you swap out the computer... your keys will no longer start the car. The reason is that your current ICU is not associated with the new ECU.

You have two options to correct this problem

1) Have Honda reprogram the ECU/ICU to play nice.

2) Install the ICU and ECU from the wreck you got the 5 speed computer out of, and have Honda use it's new T5 key system to copy a key from the wreck.

Option 1 - Reprogramming the ICU and ECU to work together.

The Prelude was Honda's most stolen car in the early 1990's. (I had a friend who's 4th gen was stolen, used in a drive-by shooting, used to store a dead body, and burnt down to the ground. The insurance company gave him $2000.00 more than he paid for the car because the prices had risen due to demand.) Honda decided to implement a key system where a computer chip was embedded into the key and would be coded to the car for the purposes of starting it.

Originally, the entire system needed to be reprogrammed during the following conditions:

- Swapping out the ECU for any reason.
- Replacement of keys (for any reason).
- Failed ICU
- Loss of the Red key (required for any of the above) with also requires replacing the ICU.

So, if you need to reprogram the ICU/ECU combo, you need to take your car to a Honda dealer. Honda will ask you for the RED learning key. They will then reprogram the ICU/ECU system. This process involves the following:

1) Insert the RED learning key.
2) Call Japan and recieve a special programming code.
3) Attach the Honda PGM-Tester and reprogram ECU.
4) Provide the car with all of the black/grey keys that are allowed to start it.

You will generally be charged for an hours labor to accomplish this task. At this point the new ECU and old ICU (or new one if you lost your RED learning key) will be able to start your car.

Option 2 - Honda's T5 key system.

After a while Honda noitced that they had a problem. People we getting pissed off every time they needed a replacement key and it was costing them $100.00. ($25 for the key, $75 for the hour) [I actually bought the remote entry system / alarm for the car because it was $250.00 as opposed to wasting the cash when my primary use black key started to wear from unlocking the driver's door...]

Now they have a system where they can copy you current Black or Grey keys:

The T5 version of the keys allows them to take you key code (that should be attached to the Red Learning Key box if you are the original owner) and internal chip code, then duplicate the key completely. In order words, you can now have the key cut to your ignition switch / lock cylinder format, but have the electronic signature that the another ICU/ECU combo is current programmed for to a new T5 key.

For example I go to a junk yard and get the ICU / Ignition Switch (w/ key) / ECU out of a wrecked 5th Gen Base Model 5 speed. I decide I want to be able to drive the car right away after the swap, but don't want to deal with Auto ECU idling problems. Therefore, I go the the Honda dealer and ask them if they've got the new T5 key system? I then ask them to use my key code to cut the key for use with my current ignition key pattern. However, I give them the key from the wreck. This results in my key pattern for my original ignition switch and the wreck's ECU/ICU codes being programmed into the a new T5 key. The important thing to remember is that you need replace both the ICU and ECU in your car with the wreck's ICU and ECU. Once you determine it is actually working, you go back and get as many keys as you need cut. (I'd wait in order to verify that the junk yard gave you everything from the same wreck... as you need the ICU / ECU / Keys from the same exact wreck.)

-Gerhard

PS a very few folks have indicated that it may now be possible for some dealers with the right equipment to teach the ICU and the ECU to work together without the Red Key. This seems to be equipment related: Some dealers may have the latest honda eletronic gadgets that will perfrom this feat, but most don't!