This applies to the following Honda ECM computers: P0A, P0B, P0C, P0H (OBD-I), P11, P12, P13, and P14.
Installing a performance chip on 1993-1995 Honda Prelude and 1994-1995 Honda Accord is a simple procedure that consists of removing the stock chip, soldering a 28-pin DIL socket in its place, and inserting the performance chip on the socket.
Unlike the OBD-I Civic ECM and Integra ECM, the OBD-I Accord and Prelude ECMs do not require the installation of extra parts other than the performance chip. It has a stock chip that can be replaced, making it simpler in a way, but tougher at the same time in another way, because you will need to desolder the stock chip, which is held in place with soldering at the top and bottom sides of the multi-layered circuit board.
This job requires average skills in electronics soldering, but if you can not do it, you can always bring the computer along with the performance chip to any TV shop or electronics trained technician, so they can install it for you. All connections should be verified before and after soldering the 28-pin socket. Take care not to bridge connections with soldering or break circuit traces by overheating the circuit board with the soldering iron. The parts are mounted on a multi-layered circuit board, which is sensitive to excessive heat. Always clean the finished job with alcohol and inspect for potential connection problems before installing the 28-pin socket.
The Honda Accord and Prelude ECMs are located at the passenger’s side kick panel. After locating the ECM computer in your vehicle, remove the bolts that attach it to its place and carefully disconnect the wiring harnesses that are plugged into the ECM terminals. The wiring harnesses can be disconnected by pushing a plastic clip, located on top of each one of the connectors and pulling it back carefully.
This installation is needed only once. Then you will be able to pull out one chip and insert any other, every time you want to switch between “Stock” and “Power” modes. These instructions cover all 1993 to 1995 (OBD-I) Honda computers that are listed at the top of this page for Accord and Prelude.
For installing the chip, just find the 28 pin chip marked as “M38256AP-xx” (see the picture below). It must be unsoldered and replaced with the 28-pin chip socket, and then the new performance chip could be inserted into it. Make sure that you align the chip so pin #1 goes to the same place as the old chip (lower-left corner of the chip in the picture below). No other parts are needed on these models. After inserting the chip, just put the ECU back together and reinstall it in your car.
Note: The “xx” after the “M38256AP” is different on every ECU computer. It is the code of the program written inside the chip. The picture below is an example of the Honda Accord’s P0A-A51 (F4). For the P0B ECU, it will be “F5”, for P14 ECU it is “C8”, and so on. So before buying a performance chip, you should first open the ECM and check that number to make sure the chip will fit your model, as every ECM model could be different.
Every ECU has an identifier code. For example, the Prelude’s P13 has 4 different codes, which are “A6”, “E6”, “C2” and “C3”. On this case, the code depends on the Domestic Market of the ECU. So, A6 and E6 are Japanese (JDM) and both programs are different. C2 is for the USA ECU (USDM) and C3 is for the UK European ECU (UKDM).
One technique for removing the chip, though still requires patience, is soldering all the pins one by one by putting excess new solder. That way, the solder will come out easier when using any vacuum desoldering tool.
Never use soldering iron above 35 watts with these ECMs to avoid destroying circuit copper traces and connections or damaging the chip internally. Always apply soldering flux to the area to be worked out, before starting any job on the circuit. It will greatly help to do the job, as it cleans and rejuvenates soldering when heated.
After finally removing the old chip, you must clean the area with alcohol and remove excess soldering by using desoldering copper braid and then check the whole area for broken traces or potential connection problems before you solder the 28-pin socket in place.
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