GM TPI and TBI cars and trucks use a 56 pin delphi connector assembly. (two actual connectors) Racetronix and others sell a cheap connector soldered to a board which can be installed in an old GM ECM case using a pair of standoffs. For the Megasquirt we have chosen the Microsquirt MODULE for it's low cost and number of features. It is used in a number of commercial PNP megasquirt ECU's. The purpose of this project is a cheap plug and play Delph56 ECM that retains the factory ECM case for a stock look, and is under $400. EMISSIONS DISCLAIMER: Megasquirt does NOT have out of the box is Emissions logic built in. The Megasquirt does NOT have a special system of beeping 'codes' to you if a fault exists. Such things must be programmed using logical outputs or CAN.
First we start with the Delphi 56 connector from Racetronix. Part # RHCA-001
Next we purchase the Microsquirt Module http://www.microsquirtmodule.com/ from DiyAutotune.
You will need a Tuner cable. Straight thru DB9
And a surface mount female DB9 connector.
Wiring a 4 wire GM Stepper IAC (Click here)
I purchased TWO microsquirt header kits, mainly because I wanted to use the standoffs in my '747 ECM case. You can also purchase the 4-40 x 7/16" standoffs on ebay and source screws locally.
Microsquirt Header kit
The following chart is how you need to pin your Microsquirt 2.2 MODULE to the reacetronix adapter board. This is based on a GM 1227165 ECM. I used 22 awg wire for my jumpers. The pins listed as "'165" are the Racetronix module side, and the pins listed as "MS" are the Microsquirt J2 side. The IAC pins come from your IAC board. GM PIN GM Circ Desc MS DESC MS PIN NOTES ---------------------------------------------------------------------------------------------------------------- A1 Fuel pump Relay Requires inline relay (see below) A2 AIR VALVE PORT SOLENOID A3 CANISTER PURGE A4 EGR SOLENOID A5 SES LIGHT A6 IGNITION SWITCH Battery Power 1,2 Splice to boath + IAC adapter A7 TCC Lockup ALED/GPIO 7 Accel led, general purpose I/O A8 ALDL Connector DATA A9 ALDL Connector DIAG A10 VSS INPUT A11 MAF GROUND (TERMINAL B) +5 Vref 15 Provide +5v to MAP (SPLICE) A12 SYSTEM GROUND GROUND 37 B1 BATTERY always on B2 Fuel Pump Sense (CONTROL) B3 NOT USED B4 NOT USED B5 NOT USED B6 VATS (passkey sytem) B7 ESC Module (knock) Spare ADC 1 17 Spare 0-5 volt ADC for knock read B8 A/C INPUT Request B9 NOT USED B10 PARK/NEUTRAL (Grounded in Drive) B11 NOT USED B12 MAF INPUT (Terminal C) MAP 3 MAP sensor 0-5 volt ADC C1 Cooling Fan Relay WLED/GPIO 11 Warm led, general purpose I/o C2 AIR VALVE CONVERTER SOLENOID C3 IDLE B LO IAC 1B Connect to IAC adapter module C4 IDLE B HI IAC 1A Connect to IAC adapter module C5 IDLE A LO IAC 2A Connect to IAC adapter module C6 IDLE A HI IAC 2B Connect to IAC adapter module C7 NOT USED C8 4th gear switch Can be used wit relay for TCC C9 NOT USED C10 Coolant Temp Sensor Coolant 5 Coolant temp 0-5v C11 NOT USED C12 Manifold Air Temp Sensor MAT 9 Manifold air temp 0-5v C13 Throttle Position Sensor TPS 13 TPS signal 0-5v C14 +5 VREF +5 VREF 15 Voltage for 5 volt sensors C15 EGR Diagnostic switch C16 BATTERY always on D1 GROUND Ground 35 Engine block D2 TPS,CTS, MAT Ground Sensor ground 33 Return ground for all 5v sensors D3 SYSTEM GROUND Ground 39 Engine block D4 EST CONTROL Opto In (+) 19 "PIP" for EDIS Box D5 EST Bypass IGN1 48 "SAW" for EDIS box D6 o2 GROUND Ground 41,43 Engine Block D7 o2 Sensor o2 27 Wideband preffered, 0-5v D8 NOT USED D9 NOT USED D10 SYSTEM GROUND Ground 49 Engine Block D11 A/C Pressure switch D12 MAF Burn Off Relay D13 NOT USED D14 NOT USED D15 Injectors 1,3,5,7 INJ1 24,26,28,30,32 Injector Driver #1 D16 Injectors 2,4,6,8 INJ2 34,36,3,40,42 Injector Driver #2 Splice Pin 21 on the J2 connector to Pin 35 or 49 (Ground) on the J2 connector. MAP SENSOR: Unplug both MAF relays and discard. Remove the MAF plug, and replace it with a MAP sensor plug wiring as follows: MAF PIN C -----> MAP PIN B (SENSOR OUTPUT) MAF PIN B -----> MAP PIN C (+5 vref) MAF PIN A -----> MAP PIN A* MAF PIN A could potentially pick up electrical noise since it is a common ground to D1. You could instead splice MAP PIN A to the sensor ground (D2) leading to the TPS. Do NOT try to do this in the ECM case, as MAF PIN A is spliced to D1 in the wire loom. Fuel pump control is NEGATIVE, not POSITIVE like GM. A second relay MUST be added. I used a small 40 amp relay found in any auto parts store and stuck it inside the ECM case. Here is how I wired mine: 30 to Battery (B1 on D56 connector) 87 to FACTORY Fuel Pump relay (A1 on D56 connector) 86 to swiched ignition (A6 on D56 connector) 85 to pin 22 on microsquirt If you have done it properly, on power up, the MS will engergize the relay for 5 seconds. So you will hear CLICK count to 5, CLICK again. This will give you the +12 volts you need on pin A1. Other optional features you may need: Pin 7 is tied to A7 above. It is a grounded output and can be used for a shift lamp, TCC clutch, or any other device that requires a ground to enable. In the software you can ground this pin under just about any running condition. (nitrous, alky injection, etc) If you are going to use it for a TCC, make sure you wire it through a relay that is only on when in 4th gear!!! Pin 11 in the above chart is used for your cooling fan. It has the same logical control as pin 7. You can use it for the cooling fan, or some other purpose. Pin 16 is an ADC channel, which takes in a +5 signal. It can be used for a voltage MAF or any other device that gives a 0-5 volt signal. (VSS, GPS, whatever) Pin 17 is another ADC channel. The chart above uses it for Knock sensor control. It can be used for any purpose that checks a +5 input just like pin 16. EXTRA PINS: Pin 10 is CAN H, and pin 12 is CAN L. These are used to communicate with other devices (Such as a transmission controller, heads up display, etc) using the CAN BUS protocol. If you would like to use these, extend them to some free pins on the D56 connector. Pin 18 is for a FLEX FUEL sensor. Can be used for Nitrous control, Launch control. Pin 20 is the FIDLE pin. It can put out a variable frequency, for example to use with a boost control solenoid for electronic boost control. J1 Pin1 - PA0 Can be used for boost control, launch control, I/O extension. J1 Pin2 - PE1 Table switching. Can be used for manually selecting between street / race / valet tunes.
On the above picture, the yellow board is the IAC circuit. The relay is for the fuel pump.
Complete closed case with serial port:
Once you have completed assembling the board, you will need to upload the firmware over your serial cable. This is very simple. *** MAKE SURE YOU USE MS2EXTRA CODE *** 1) Download either pre-compiled firmwhare, or compile your own ms extra _us.s19 file 2) Run the MS firmware utility 'ms2loader_win32.exe' 3) Select 'Microsquirt', and your comm port settings 4) Ground pin 8 on the Microsquirt and power up the unit. (bootjumper) 5) Follow the on screen directions. Once firmware is uploaded, power down the unit and remove the ground from pin 8.The latest firmware can be found here
You are now ready to open Tunerstudio and tune.
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