How to attach Honda S300 unit to OBD1 Honda ECU

The Hondata S300 is one of the most advanced OBD1 Honda tuning systems available on the market. The S300 has the ability to operate VTEC or non-VTEC D, B, F, or H series Honda engines, and its advanced boost control features make it one of the most versatile Honda tuning systems. .. The only drawback of the Hondata S300 is the difficulty of installation. The S300 is more complex than a typical “piggyback” tuning system because it is actually installed inside an ECU where a typical performance chip is installed. Another drawback of this system is that when you buy the S300, you only buy the Hondata unit and software. It’s up to you to arrange to install it. However, this step-by-step tutorial will allow you to successfully install the Hondata S300 on your OBD1 ECU.

The first step to a successful installation is to make sure you have everything you need. This is a rather complicated process, but with the right equipment and components, it should go smoothly. The Honda S300 (part number S300) is designed for rectangular or “large case” OBD1 Civic / Integra style ECUs on the US market (USDM). Honda’s part number S300J is designed for JDM (Japanese Market) Square Case OBD1 Civic / Integra Style ECUs. These are not compatible, so make sure you have the right S300 unit for your ECU. This installation guide applies only to USDM variants. Honda ECUs that can be used with the S300 are P06, PR4, P28, P30, P61, P72, and P75. Non-vtec ECUs are intended to be used only in non-vtec applications. If you use a P06, Pr4, or P75 ECU, you must also perform a non-vtec to vtec ECU conversion in your Hondata S300 installation for the VTEC engine to work properly.

let’s start. Loosen both the top and bottom lids from the ECU and set both covers aside. There is a small Phillips screw on the side of the ECU where the wire harness plug is located. Completely remove this screw and the small metal fixture that secures inside the ECU case and set it aside. Turn the computer over, remove all the screws that secure the circuit board to the ECU case, and note that it is slightly different from the screws on the ECU cover. The ECU board can now be removed from the bottom of the ECU casing. If you need a little extra persuasion to release the board from the case, be especially careful not to damage the ECU board or its connectors.

Now that the board has been removed, you can start with the fun part. Use a desolder tool or desolder blade to desolder 28 solder joints marked 27c256, 24 joints marked 74hc373, and 4 holes in the space labeled CN2. To do. There are 5 holes in the CN2 section of the board. The solder joint farthest from the ECU connector is not used and can be left filled. Most boards have two solder joints labeled R54. These also require solder removal. Ignore this step if the ECU does not have an area labeled R54 directly above the 28-hole area marked 27C256. Clean all areas of the flux-soldered ECU to make sure there is no loose solder on the board or in the way of the desoldered holes. To enable the data logging feature of the Hondata S300, amputate one leg of the resistor at the location labeled j12. For a clean look, remove the solder completely and remove the resistors, if necessary.

Next, move on to installation. The best way to ensure that the complete solder adheres to the joint is to apply a thin layer of flux to the back of the desoldered joint before proceeding to the next step. Start by installing two rows of 14-pin strips in the empty holes associated with the area labeled 27c256. Make sure the pins are facing up on the ECU board and that you are soldering the pins to the back of the board that protrudes from the desoldered holes. Then attach the 24-pin tip that came with the S300 to the space labeled 74hc373. Make sure the tip’s half moon notch points toward the ECU plug before soldering in place. Insert the 4-pin strip into the perforated hole labeled CN2 and solder it in place. The CN2, which is farthest from the ECU plug in the previous step, should have one empty hole left. If the ECU has a space labeled R54, solder the included resistors in place. Polarity doesn’t matter. It can be installed in either direction. Then push the Hondata S300 circuit board firmly into place in two rows of 27c256 pins 14 and CN2 pins 4. Take great care not to bend or break the pins. After installing the Hondata S300 board, carefully slide the ECU board back into the ECU case. Mark the area blocking the S300 USB plug on the ECU casing. Carefully remove the ECU board from the casing again and use a grinder or hacksaw to cut out the marked area so that the USB cable can be connected to the S300 USB port.

Thoroughly clean the ECU casing and circuit board with a high quality electrical component cleaner to remove debris and residual solder flux. Reinstall the ECU board in the casing, being careful not to damage the components. Install the screws that secure the circuit board, the small screws and metal clips next to the plug, and the ECU covers on both the top and bottom. Carefully attach the new flashy Hondata sticker to the ECU for proper operation.