V3.0 / V3.57 External wiring

This is a general external wiring layout. See the ignition hardware manual for details on controlling different ignition systems and the DIY options for multiple spark outputs. SPR1,2,3,4 and IAC1A,1B,2A,2B are not connected to anything as standard - there are solder-pads on the circuit board inside the case that you can DIY connect to input and output circuits of your choice. Remember that Megasquirt-1 does not support stepper idle, so those pins are always free for DIY.
V3.0 board requires a DIY modification to directly control a 2-wire PWM idle valve as shown. V3.57 is ready to use.

V2.2 External wiring

This is a general external wiring layout. See the ignition hardware manual for details on controlling different ignition systems and the DIY options for multiple spark outputs. X11,12,13,14 are not connected to anything as standard - these are solder-pads on the circuit board inside the case that you can DIY connect to input and output circuits of your choice. A DIY modification is required to directly control a 2-wire PWM idle valve as shown. With some careful soldering directly to the DB37 pins, pin36 can be utilised too (e.g. ignition output)

Harness Adapter / DIYBOB
DIYautotune offer a harness adapter that can be used to more easily integrate the Megasquirt wiring loom to your existing loom. A range of adapters are available that plug into your stock loom connector. Soldering is required to join the loom pigtail to the adapter, but your stock loom is typically unchanged.
See the DIYautotune DIYBOB page

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No part of this manual may be reproduced or changed without written permission from James Murray and Ken Culver.