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 AECU or TCUYellow
Output ASolenoidWhite
Input BECU or TCUOrange
Output BSolenoidPink
Input CECU or TCUDark green
Output CSolenoidLight green
Input DECU or TCUBlue
Output DSolenoidPurple
PowerSwitched 12VRed

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