In light of some people recently asking how to wire up there megasquirt, I figured I would make a dummies guide. I will be using my stickied thread from the 1st gen forum to help with this also. See my sticked thread for pcm pinouts.

Megasquirt Pin #/ 1995 Neon PCM Pin # Pin 1 - not used Pin 2 - not used Pin 3 - Shift Light Output / N/A Pin 4 - Fan Relay Control Output / Pin #19 K17 DB/PK - connect this wire to ms only if using it to control fans Pin 5 - Boost Control Solenoid / N/A Pin 6 - Tachometer Signal Output / N/A Pin 7 - Ground Pin 8 - Ground Pin 9 - Ground Pin 10 - Ground Pin 11 - Ground Pin 12 - not used Pin 13 - not used Pin 14 - not used Pin 15 - not used Pin 16 - not used Pin 17 - not used Pin 18 - not used Pin 19 - Ground Pin 20 - Mat Signal / Gm IAT or Pin # 6 K21 BK/RD - only connect to this pin if using stock IAT sensor Pin 21 - CLT Signal / Gm CLT or Pin # 28 K2 TN/DB - only connect to this pin if using stock CLT sensor Pin 22 - TPS Signal / Pin # 10 K22 OR/DB - send this signal to both ms and stock pcm Pin 23 - O2 Signal / Wideband Signal or Pin # 8 K41 BK/DG (upstream o2 sensor) - only connect to this pin if using stock o2 sensor Pin 24 - Tach Signal / Pin # 25 K24 GY/BK - send this signal to both ms and stock pcm Pin 25 - Knock Sense or Table Switching Input / N/A Pin 26 - TPS VREF / N/A - this is a 5v reference Pin 27 - EGT Sender Input / N/A Pin 28 - 12v To MS / Pin # 54 F18 LG/BK - this is 12v in start and run Pin 29 - Launch Control Input / N/A Pin 30 - Fast Idle / N/A Pin 31 - Ignition Output B / Pin # 1 K19 BK/GY - connect to ms only Pin 32 - INJ1 / Pin # 4 K11 WT/DB (Injector 1) - connect to ms only Pin 33 - INJ1 / Pin # 24 K14 LB/BR (Injector 4) - connect to ms only Pin 34 - INJ2 / Pin # 23 K12 TN (Injector 2) - connect to ms only Pin 35 - INJ2 / Pin # 3 K13 YL/WT (Injector 3) - connect to ms only Pin 36 - Ignition Output A / Pin # 21 K17 DB/TN - connect to ms only Pin 37 - Fuel Pump Output / Pin # 38 K31 BR - this is fuel pump relay ground

Megasquirt Pin #/ 1996-1999 Neon PCM Pin # Pin 1 - not used

Pin 2 - not used Pin 3 - Shift Light Output / N/A Pin 4 - Fan Relay Control Output / Pin # 54 C27 DB/PK (1996) - connect this wire to ms only if using it to control fans Pin 4 - Fan Relay Control Output / Pin # 18 K173 DG (1997+) - connect this wire to ms only if using it to control fans Pin 5 - Boost Control Solenoid / N/A Pin 6 - Tachometer Signal Output / N/A Pin 7 - Ground Pin 8 - Ground Pin 9 - Ground Pin 10 - Ground Pin 11 - Ground Pin 12 - not used - Pin 13 - not used - Pin 14 - not used - Pin 15 - not used - Pin 16 - not used Pin 17 - not used - Pin 18 - not used Pin 19 - Ground Pin 20 - Mat Signal / Gm IAT or Pin # 37 K21 BK/RD - only connect to this pin if using stock IAT sensor Pin 21 - CLT Signal / Gm CLT or Pin # 26 K2 TN/DB (SOHC) - only connect to this pin if using stock CLT sensor Pin 21 - CLT Signal / Gm CLT or Pin # 26 K2 TN/BK (DOHC) - only connect to this pin if using stock CLT sensor Pin 22 - TPS Signal / Pin # 35 K22 OR/LB - send this signal to both ms and stock pcm Pin 23 - O2 Signal / Wideband Signal or Pin # 30 K41 BK/DG(upstream o2 sensor) - only connect to this pin if using stock o2 sensor Pin 24 - Tach Signal / Pin # 32 K24 GY/BK - send this signal to both ms and stock pcm Pin 25 - Knock Sense or Table Switching Input / N/A Pin 26 - TPS VREF / N/A - this is a 5v reference Pin 27 - EGT Sender Input / N/A Pin 28 - 12v To MS / Pin # 20 F12 DB/WT - this is 12v in start and run Pin 29 - Launch Control Input / N/A Pin 30 - Fast Idle / N/A Pin 31 - Ignition Output B / Pin # 3 K17 DB/TN Pin 32 - INJ1 / Pin # 16 K11 WT/DB (Injector 1) - connect to ms only Pin 33 - INJ1 / Pin # 16 K14 LB/BR (Injector 4) - connect to ms only Pin 34 - INJ2 / Pin # 17 K12 TN (Injector 2) - connect to ms only Pin 35 - INJ2 / Pin # 7 K13 YL/WT (Injector 3) - connect to ms only Pin 36 - Ignition Output A / Pin # 2 K19 BK/GY Pin 37 - Fuel Pump Output / Pin # 74 K31 BR - this is fuel pump relay ground The Neon pin numbers are for the connectors at the PCM. I have also been thinking recently about making some plug and play super420a's but in order for me to do this I would need you megasquirt and an old PCM, Alternator Voltage Regulator, and I would need to know what all sensors you would be using. This would completely get rid of the stock computer and just leave the megasquirt as the only controlling device. Since this would be a complete standalone, if you needed to pass smog you would have to put a stock computer back in because the MS doesnt have OBDII compatability and would cause you to fail.