OBD1 Honda ECU PWM Boost Control Kit Installation Instructions

We sell the components required for this conversion as a complete kit here: OBD1 DIY PWM Boost Control kit

This guide covers the installation of components required to add PWM boost control functionality to a USDM OBD1 Honda/Acura ECU. This modification provides a PWM output on A11 for controlling a 3‑port MAC valve directly from the ECU, commonly referred to as “Boost by Gear.” After performing the hardware installation, you must use an EEPROM or emulator with tuning software that supports PWM boost control (e.g., Hondata S300v3) to configure and activate the feature.

Required Components

  • 3055T NPN transistor (Q29)
  • 1N4002 diode (D14)
  • 220Ω resistor (R70)
  • 330Ω resistor (R71)
  • PNP transistor (Q20) – install only if missing
  • ECU harness pin for A11 (to connect to boost control solenoid)

All components are included in our PWM Boost Control kit.

Installation Steps

1. Install 3055T Transistor at Q29

  • Solder the 3055T transistor into the Q29 location.
  • Ensure proper orientation by following the footprint markings on the board.

2. Install Diode at D14

  • Solder the 1N4002 diode to location D14.
  • Align the stripe on the diode with the stripe indicated on the PCB silkscreen.

3. Install resistors

  • Solder the 220Ω resistor at position R70.
  • Solder the 330Ω resistor at position R71.

4. Install PNP Transistor at Q20 (If Not Present)

  • Check if Q20 is populated. If missing, solder the PNP transistor into this location, matching the orientation to the board silkscreen.

5. Add ECU Harness Pin to A11

  • Insert the provided ECU harness pin into location A11 of the ECU connector to output the PWM signal to the MAC valve.

Final Notes

  • Once these components are installed, the ECU hardware will support PWM boost control.
  • You must configure boost control within your chosen tuning software (e.g., Hondata SManager).
  • A properly wired 3‑port MAC valve is required (typically 12V supply and ECU PWM ground control via A11).
  • Refer to the highlighted board diagram for exact component locations.