Tweet
Installation
Wiring the megasquirt into the vehicle is a unique challenge. I highly recommend using a factory engine harness and tapping into the factory ECM plugs. Leave them intact in the event you ever need to go back to stock. The following diagram will help you get started.
GM DIS
- Module pin B or C - white wire - DB37 #36 (V3 main board, ignition output signal pin for V2.2),
- Module pin A - tan/black wire - Connect to a bypass relay as shown for the HEI modules
- Module pin E - purple/white wire - DB37 pin #24 (tach),
- Module pin F - red/black wire - ground,
- Module separate connector - black/white - ground,
- The module also has connections for power (pink), the crank position sensor (yellow & purple), and tach (white).
Note on the bypass relay http://www.megamanual.com/ms2/GM_7pinHEI.htm
I installed this relay but never needed it. I did not have a problem starting the car with this relay not installed. If you are unable to start the car, install this relay.
GM DIS needs a dwell setting of 25ms. To set the dwell to 25.0, you'll have to change the megasquirt-II.ini file which can be found at C:\Program Files\Megasquirt\MS2-MicroSquirt BG 2.890. Edit the following line with Notepad.exe (installed on most Windows systems, look under 'Start/All Programs/Accessories') or a similar text editor:
max_coil_dur = scalar, U08, 4, "ms", 0.10000, 0.00000, 1.00, 8.00, 1 ; * ( 1 byte)
to
max_coil_dur = scalar, U08, 4, "ms", 0.10000, 0.00000, 1.00, 25.50, 1 ; * ( 1 byte)
Fuel Pump Relay
After you've wired in your MS and key on, the megasquirt should turn on. When it turns on you should hear the fuel pump relay click and the fuel pump should run. If it does not, it's because your GM ECM triggered the fuel pump relay with a + signal. The megasquirt uses a - to trigger the relay. So you may need to switch pin 86 to a 12V+.
Using a non-electric trans with a Torque Converter Clutch (TCC)
You can wire the TCC to pin 30 (fast idle) on the DB37. Settings for software will come later.
If you have any problems wiring in your MS, refer to http://www.megamanual.com/v22manual/mwire.htm
