MS Harness Assembly

Let's start with the harnesses.

You'll wanna use these pinouts:


Full size:


Full size:


Full size:

The '95.5-'05 Standalone users require a Tach output circuit.


The IAC— I/Os on the MS are connected to these DB37 pins:

IAC1A -DB37 pin 25
IAC1B -DB37 pin 27
IAC2A -DB37 pin 29
IAC2B -DB37 pin 31

Just in case you need to know this for a CAS install in an NB or for whatever reason, this is the CAS pinout:
CKP- Pin 24
CMP- Pin 25


You'll build your DB37 connector like this:


There are three options to install the MS:

First, being a boomslang. This allows you to plug your MS wiring in between the ecu and factory wiring so the installation can be completely reversible without damage to the factory harness. This method should stop being utilized.

to build yours you'll need to follow parts:

  • (1) 64 Pin Male connector (174518-7)
  • (1) 26 Pin Female connector (174516-6)
  • (1) 22 Pin Female connector (174515-6)
  • (32) .040" Contacts (175061-1)
  • (16) .070" Contacts (173631-6)

96-97 add:

  • (16) .040" Contacts (175061-1)
  • (1) 16 Pin Female connector (174514-6)

all part numbers are tyco / amp, and can be purchased at places like See for more vendors and availability. this should run you $20-$30.

TRY for no minimum purchase amount or add an extra DB-37 to offset the minimum

*(1) DB37 Solder Cup (5-747017-2)
*(1) AMP cable clamp kit (5749916-2)



Option #2

the second option is running standalone.

The only part you'll need to make your harness is the 64 pin connector. Wire the db37 harness directly to the connector and then just plug it in the factory harness.


On 90-95 installs, a 1K 1/4 watt resistor should be installed in the diaganostics box across B+ and IG- Without this resistor the dash tach will not be functional because the stock ECU provides this pull-up; since we remove the stock ECU, we must replace the pull-up.

On 95.5 and up installs, the tach output circuit must be built into the MS and sent to the labeled pin on the harness as shown above.

The 3rd option is wiring the DB37 harness directly into the factory harness.

An option here is wiring switch for the ignitor and injector paths so you can have either the MS or oem ecu control them at will.

Here is a stand alone wiring diagram from miatamoxie on Thanks!


thanks Joe

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