Using the HSD-4 High Side Driver

HSD-4 High Side Driver Module Overview

The HSD-4 high side driver module provides four high side drivers for solenoids that need 12 volt power instead of ground. Wire a ground triggered output from an MS3-Pro, MicroSquirt, or MegaSquirt to the HSD-4’s input, and it will supply a 12 volt output with up to 8 amps of current. Use it for medium current solenoids that have to be switched faster than a mechanical relay and require a 12V signal. Usually, solenoids that need a high side driver ground through the solenoid housing and have a single wire connection.


HSD-4 wire colors

Function Connects to HSD-4  wire
Input A ECU or TCU Yellow
Output A Solenoid White
Input B ECU or TCU Orange
Output B Solenoid Pink
Input C ECU or TCU Dark green
Output C Solenoid Light green
Input D ECU or TCU Blue
Output D Solenoid Purple
Power Switched 12V Red

The red wires should all be grouped together and connected to a single fuse to 12 volt switched power. The fuse should be rated for the total current draw of all outputs being used, up to a maximum of 30 amps.

ECU connections

The inputs need a ground signal to trigger their outputs. Here are what outputs you can use to trigger the HSD-4 high side driver with DIYAutoTune engine or transmission management.

MS3-Pro: High current, PWM, injector, or tach outputs

MSPNP Gen 2: Output 1, output 2, boost, or tach outputs

MicroSquirt (transmission control): Shift solenoid, TCC, or EPC outputs

MicroSquirt (engine control): ALED, WLED, FIDLE, or tach outputs

MS3X: Mid current, tach, or injector outputs

MS1 or MS2: Relay control outputs or FIDLE (MS2 only)

GPIO board: General purpose, PWM, or high current outputs