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