GM Delco to Megasquirt on the cheap - 2012-2016

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. 


Not scared? Let's get started!


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.

IDLE CONTROL:

Microsquirt IAC kit

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

ASSEMBLY!

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 humpers. 

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  Dist Ref LO (GROUND)             SENSOR GROUND    33                       Provides ground for dist module
B4  NOT USED
B5  Dist Ref Hi                      Opto In (-)      21                       
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                      IGN1            48                        Ignition control
D5  EST Bypass                       IGN2            44                        "set timing" connector, +5v 
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 19 on the J2 connector to Pin 15 on the J2 connector. Pin 19 is Opto+ IN. What this will do, is allow
the software to provide +5 volts on pin 44 to tell the distributor that the ECM is controlling timing. 


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. 


Fully assembled. A more skilled electronics geek could do a better/neater job on the jumpers:

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. The links below contain a starter project
for TPI. Please go over all of the settings and make changes as 
needed for your application. 


Starter project files you need these!

Wiring docs and schematics you might want

GM VSS converter you might want


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