91-93 Turbo Swap Wiring Info
Updated 11-13-04

Step-by-Step Swap Turbo Swap Instructions can be found HERE

91-93 Mustang Turbo Swap Instructions (Updated 6-12-03...See Pin 49 Below)
by Igloo75 & Stinger (Me)

If you want a printable checklist while you are doing the swap, left-click or right-click/save-as here:
Turbo Swap Instructions

1. Intro

This is specific to the 91-93 LX cars receiving the '87-88 TC computer and VAM harness. 

These notes are for a 5speed car only, but should be close if you wanted to do an auto trans conversion. (who would do that)?
I have noticed elsewhere that others have had problems with their airbag systems and the IRCM wiring. With this wiring there is no problems with that.

First off try to use as many pieces as possible from an 87-88 Turbo Coupe, as it will simplify the conversion process. You do not need the whole wiring harness from the t-bird, only a few connectors. you will need the VAM harness connector, the knock sensor connector (I did not use a knock sensor), and you will also need the coil connector.

DO NOT remove the harness from the Mustang.  You ARE NOT using the Turbo Coupe harness in your Mustang.  There are many wires for sensors and modules in the Mustang harness that are not used with the turbo engine, such as the MAF wires and the DIS ignition wiring.

Read this article carefully and you should be set on how to wire the conversion. if you do not understand something feel free to study that area until you do understand. If you do not you could end up messing up something that could be costly to repair.
Also feel free to email me with any questions, or if you find any errors in this article. I will not accept responsibility for anything you might fry in the process of doing this swap. I advise researching all the wiring diagrams and EEC4 info you can get your hands on.



2. Re-pinning the computer

I am not going to explain how to remove and install pins from a connector, if you can't figure it out you might not want to do this swap.  I will give you a hint though, a small screwdriver or small razor knife works well.
SEE CHART BELOW FOR PINOUTS!!!!



3.How to Connect VAF Wiring

To do this part find the MAF connector and cut it off about an inch from the connector (4 wires). now splice in 3 of the wires from the VAF pigtail as follows: (soldering recommended)

Now at the computer move the ltblu/red wire from pin#14 to pin #43
next at the computer move tan/ltblu wire from pin#15 to pin #27
(Both of these steps are mentioned again when doing the rest of the ecu repinning)
note 1: For the 4th wire (or/wh) you need to run a wire from this to the brown/white wire at the BARO sensor. This is a 5v reference.



4. Wiring the ignition

The original harness section of the N/A engine is removable from the main portion of the wiring harness. I recommend laying it out on the bench to do this project as this is the worst of the wiring. There may be some questions about this part of the wiring as far as routing of a few of the wires you will need to figure out on your own. I will show you where to connect them.

Once you get the harness section out take all the wire loom and tape off the whole section of harness.

Find the two connectors that originally went to the DIS module (one is black, one is grey)

Now take the TFI ignition module connector from the T-bird wiring and use this as a wiring reference to get the order of the wires correct, as you will be repinning the grey DIS Mustang ignition module connector to match the TFI wiring harness of the turbo motor.

Wiring from the top of the t-bird connector:
dark blue ---------->(PIP)
yellow/light green--->(SPOUT)
red/light blue------->(crank signal)
red/light green------>(12V ignition)
white/light blue----->(tach, IDM)
black/orange------->(ground)

Now, for reference, the DIS connectors "should" be wired like this in stock form (the colors vary a bit year to year):

Grey connector from top:               Black connector from top:
orange/red (foil wrapped)               blue/yellow
tan/blue                                      tan (or pink)
tan/green                                    blue
tan/orange                                  grey/orange
tan/white                                    blue/tan (or red/light blue)
tan/yellow                                   red/light green

Now you need to remove the pins from both of the DIS connectors above and replace them in different positions into the grey connector as follows:

From top
grey/orange----->(PIP)
pink------------->(SPOUT)
red/light blue (or blue/tan)-->(crank 12v) this wire needs to be run to the location of the small wire on the top of the starter solenoid, just put a small ring terminal on the end of it and slide it onto the small post on the solenoid
red/light green---->(12v ignition) splice into this wire and run to positive side of coil (White)
tan/yellow------->(IDM wire) splice into this wire and run to negative side of coil (Green)
orange/red------>(ground)

When I did this there is extra wires such as the crank sensor and (leftovers) from the DIS wiring. You can remove the cranks sensor wires and the extra DIS wires. The extra DIS wires could be used for knock sensor wiring if moved to the correct pins at the computer. I opted not to use a knock sensor so I cannot get into details here.  You should be able to eliminate about 6-7 plugs when it's all said and done.  When removing the old coil pack plugs, be sure to connect all of the leftover red/green wires together.

When you are done wiring this little section wrap the harness up with new loom, and tape it up nice.

Note here I used the throttle body from the DIS engine to keep from having to change any TPS wires. If you want to use the T-bird throttle body you will have to change the connector.  They are both the same size.  If you choose to use the turbo throttle body (one advantage is it has an adjustable Throttle Position Sensor), here is what I've found as far as wiring goes:

Turbo TPS Plug/Stock 1991 Plug
From Top:
Orange------->Brown/White
Green-------->Grey/White
Red---------->Grey/Red

Be sure to mount the coil behind the battery with the factory mount from the thunderbird.
Also make sure the resisotor (black box inline of the coil wiring harness ~6" from coil) gets connected to the coil positive (rd/ltgrn) and grounded well.

The Mustang Oxygen Sensor will not work with the TC computer, it will cause it to run lean.  You will need to get an O2 sensor that corresponds with the year or TC the computer came from.  If you can't get one right away, simply unplug the O2 and run it that way...it will cause the check engine light to come on occasionally.  One of the alignment tabs will need to be removed to get it to plug in...the wires are ok...no need to change any of them.

You will need to use the fuel injector harness from the Mustang so you can plug it into the stock harness.  All the wires are correct.  Make sure you don't use the Mustang injectors or fuel rail, they won't work.

Note that you will need to move that ACT Sensor that was located in your airbox to somewhere after the intercooler.  The 87-88 intakes already have them in the back of the lower intake.  You will need to move/lengthen the wires to reach the new location.  I chose to mount mine in the IC tubing right before the throttle body.

Also note I did not use the coolant temp sensor that is located in the t-bird intake manifold, I kept it in the location it is in originally in the Mustang (in the heater hose).  You will need to do this as well go get the fan to function.

If your base turbo engine is a 83-86 model you will need to rig up your own fuel lines from the rail to the steel lines located near the bell housing.  The stock mustang ones will not work.  The 87-88 cars hook right up to the stock lines.  I chose to cut the lines out of the turbo coupe and then cut them to the length needed for the mustang.  I then slid the factory style connectors into the plastic fuel line (may need to smooth out ends of connections with grinder and then lube to get them inserted all the way) and then used two small hose clamps on each one to keep them from leaking.  If was the cheapest way I could find to fix the problem.



5. Closing

I have not finished up a few details on my car such as the premium fuel switch, or the EGR solenoid wiring, so you will be on your own with those functions for now.  The only ill effect from the unhooked EGR is an occasional check engine light...nothing I can't live with.  You of course will need to run premium fuel all the time unless you wire in the premium fuel switch.
 
What I have written here will get you up and running and hopefully on the way to twisting up the boost and kicking ass.

Here are the pinouts for the computer swap:

© Gustafson 2002