Classic MegaSquirt Relay Cable

Pre-assembled, shielded cable for connecting your Classic MegaSquirt ECU to the Relay Board.

The Classic MegaSquirt Relay Board Cable is a high-quality, 4-foot DB37 cable that links your MegaSquirt ECU to the Classic MegaSquirt Relay/Power Board. Designed for reliability, this cable features metal AMP hoods, a shielded tach wire (pin 24) for noise reduction, and includes all necessary connections—including idle, ignition, and spare I/O pins (3–6) for full MS1, MS2, or MS3 compatibility.

If you've ever tried to build one of these cables yourself, you know how time-consuming and error-prone it can be. This pre-built version saves hours of labor and delivers superior shielding and build quality right out of the box.

Key Features:

• 4′ DB37-to-DB37 relay cable

• Works with MS2, and MS3 ECUs using the standard main board

• Fully populated, including IAC, ignition, and spare pins (3–6)

• Shielded tach wire on pin 24 (grounded at one end for noise suppression)

• Rugged metal AMP-style DB37 hoods for EMI/RFI resistance

• Pass-through design: remove one hood to route through a 1.25″ firewall hole

• Clean, professional-grade construction for long-term reliability

Compatibility Notes:

• This cable is designed only for use with the Classic MegaSquirt Relay Board.

• It is not compatible with the standard MegaSquirt wiring harness—these two systems are mutually exclusive.

• For wiring sensors and injectors to the Relay Board, use our Wire Bundle for a clean installation.

Pro Tip: Use this cable when you want to keep wiring centralized and easily serviceable at the Relay Board screw terminals.