DIY Ford Mustang EFI wiring harness conversion- GETTING UGLY

[ransil]

Who's good at VISIO and can make custom parts & shapes ??

 

[broncosbybart]

You guys are awesome. I am going to delete the salt and pepper engine harness connectors. Will I need to add wire between the splices or will I be ok with wire length?

Also, I haven't researched the o2 harness yet but know they are somehow different auto to manual. I have to make this harness (rather than buy one) and don't want to do it wrong. If any one can steer me, that'd be cool otherwise I will let you know what I find

 

[broncosbybart]

So, here are some pics. A word to the wise- DON'T be like me and attempt to do this in the kitchen... Fortunately my wife wasn't home and wasn't a witness to the mess being made. It is amazing how much dirt and grime this thing can accumulate.

Right now I have snapped pictures of the harness and the plugs associated with it. I won't worry about the engine harness for the moment, because that one is pretty straightforward.

I don't know how to upload the pictures as a full size image, other than using photobucket, so here is a thumbnail of the harness as bought. Then I uncoiled it and sprawled it out.

 

[broncosbybart]

You will have to bear with me- I am half colorblind so wiring isn't my forte. I can't tell you how many stereos speaker systems that I've wired wrong. Why do they need to use blue and purple for speaker wire colors??? The grey and green mess with me too.

Anyway, the first 'batch' of connectors resides in the cab of the car. Here we find:

- the big computer plug

-a ground (the one with the metal loop on the end)
-a grey round conector with 6 pins
-a rectangular plug with 5 pins used in it. This one is going to be cut off the harness down the road.
-a relay which is the EEC relay, if I am reading the diagram right.

I started on this about 10pm last night and haven't gotten very far yet...

 

[broncosbybart]

The big rubber plug separates the interior portion of the harness (in the above pic) from the rest. As we go past that plug the first batch of plugs I came to look like this. At this point I am only sure of the 1 connector.

There is a:

-big black ovalized 4 pin connector. It is for the MAF sensor.

-round black 8 pin connector. This goes to the oxygen (HEGO) wiring harness- which I don't have.

-larger white round 4 pin connector (UNKNOWN)

-smaller white round 2 pin connector (UNKNOWN)

 

[broncosbybart]

The next group of wires stems from about the same area. It is pictured here.
There is a:

-black and red 2 pin connector- Air Magangement Solenoid 1

-black and red 2 pin connector- Air Magangement Solenoid 2 (both look very similar)

-black 2 pin connector- EVR solenoid

-black 2 pin connector with 3 wires feeding it a few inches up the harness- for the AC system.

I think that all of these connectors can be done away with. I'll have to research how and if any need to have the resistors on them to prevent codes.

 

[broncosbybart]

Next up the line is the engine harness. We will leave this alone for now.

You can see in this picture that the harness is connected via the 'salt and pepper' shakers (white and black). I plan to remove this mess and solder it all together. I've been told that a few of these wires can be eliminated as well, but that is down the road from here. I would like to know if I'll need to add wire as I cut and splice, or if I can cut and splice and still have enough wire to reach everything.

 

[broncosbybart]

Next in line is an easy one. This is the pigtail for the distributor. It is a large grey 6 pin connector. The black connector next to it with the grey thing on top is the SPOUT connector. The grey part is removed to set timing if/when we get to that point...

 

[broncosbybart]

Then we run into a black 3 pin connector all by itself. This is for the barometric pressure (BP) sensor.

 

[broncosbybart]

Further down the line we have this group here. There is a:

- black 8 pin connector (7 are used)

- grey 8 pin connector (5 are used)

- large black connector with 4 wires. This is the self test connector.

- 1 grey plug. This is the self test input. It is the one that you ground when doing a diagnostic test.

I can't figure out what the black or grey connectors are for. I think they were connected to the car harness for the ignition and such. Any help?

 

[broncosbybart]

Finally we are at the end.

Here we have a:

- black wire with a fusible link in it and a looped end. That is our 12V to the battery. Black is positive, remember?? I will eliminate this fusible link in the future with a fuse.

- a black round 2 pin connector- not sure what it was connected to other than a ground and the A/C solenoid.

- a rectangular black 2 pin connnector- that is for the coil.

- a cluster of wires that terminate into 1 connector and has 2 looped ends. This is a ground.

 

[broncosbybart]

Lastly, here is the harness all stripped of the wire loom and tape. I did keep it taped together every couple of feet to keep the general shape of it intact. Now I have to find out what everything is and run tests to make sure it all is ok. Basically what that entails is using an ohm meter to test between the EEC computer plug and each end that it goes to. There should be 0 ohms (no resistance) between the pinout on the computer plug and the associated plug for it. There are a total of 60 pinouts on the computer plug. Some are vacant and there are others that will be eliminated. Right now I need to start at pin 1 and trace them all to make sure everything is ok.

The last picture is all the junk removed from the harness. Again, don't try this in the kitchen, unless you're a bachelor.

In the meantime, any who want to fill in the blanks on the above connectors, or give any other advice, are more than welcome to.

 

[ILikeBond]

Good stuff, Bart! Will definitely be helpful when I go to tackle my harness.

 

[broncosbybart]

So, I'm getting pretty deep into this. What a mess!

I've chased all the pinouts. That isn't any fun. I do have a problem with the #4 injector wiring- it is at 26M ohms- so that can't be good. I think it is a salt and pepper connector issue. Will have to check it out.

I'm also getting about 30 ohms resisitance on some other engine circuits but no resistance on the starting side of the connectors, so they are definitely going to go.

On the plus side, I've managed to identify a lot of unknown plugs. There are still others, if you want to try your hand at them.

FYI, I like this wiring diagram much better than the pinouts given on the oldfordinjection website. I printed it out and it was very helpful!

 

[anoblefox]

the most desireable OEM5 mustang 5.0 harness to use are 89-93 (mass air), the 88 calif version is also mass air. All mustang 5.0 harness 86 & 87 are speed density. Every year of the mass air versions are different pinouts with some years having wire color changes for the same circuit. Also the EGO (heated oxygen sensor harness) is different from automatic to manual. It is imperative that you use the same year and trans type EGO harness to match up with the pinouts of the engine harness. One additional thing to remember on mass air versions is to use the late mustang diode protected starter solnoid to protect the ECM from back voltage. This is the most overlooked EFI wiring concern and can cause drivability problems that will NOT set any codes.

 

[brianstrange]

I always suggest creating your own HEGO branch by the center of the engine on the ECU harness. It will clean up your wiring, and eliminate the extra wires in the factory 02 branch

 

[broncosbybart]

Here is a list of the pinouts that I created based on this harness.

-1- 12V power- goes to relay ‘in cab’ first
-2-vacant
-3- VSS + went to grey rectangular pin ‘in cab’- I cut this
-4-IDM- goes to coil (-), grey connector by STI (self test) plug, and TFI (distributor) 2nd pin. Has a 22k ohm resistor installed in harness!!
-5-vacant
-6-VSS – also went to grey rectangular plug ‘in cab’- I cut this also
-7-ECT- engine coolant temp
-8-vacant
-9-MAF
-10-A/C relay and plug. I plan to delete this
-11-vacant
-12-Fuel injector #3
-13- Fuel injector #4
-14- Fuel injector #5
-15- Fuel injector #6
-16-Ignition ground. Goes to bottom pin on TFI
-17- MIL/check engine light. Also goes to grey ‘in cab’ rectangular connector. I cut this as well.
-18- vacant
-19- to fuel pump (eventually). I cut this from the grey rectangular ‘in cab’ connector
-20- Ground (found ‘in cab’)
-21- IAB- idle air bypass
-22-Goes to STI and will go to fuel pump relay.
-23-vacant
-24-vacant
-25-ACT- air charge temp- I will cut this to accommodate the Explorer EFI position in the intake tube
-26-VREF- goes to TPS, BP, EGR, EVAP. Take your time here!
-27-EVP- plan to delete
-28-vacant
-29-Right HEGO (0xygen) sensor. Found in black round 8 pin connector
-30- Trans interface. Found in black round 8 pin connector. I need to research this!
-31-CanP- I plan to delete it
-32-AM2- air mgmt. sol. Plan to delete it
-33-EVR- plan to delete
-34-vacant
-35-vacant
-36-SPOUT and TFI. Goes to SPOUT first. Spout just carries current through it.
-37-12V Power- EVR, canP, AM1, AM2, A/C, EEC relay, IAB, all injectors, will go to fuel pump relay. Also goes to pin 57.
-38-AM1- plan to delete
-39-vacant
-40- ground (found at the far end of the harness)
-41-vacant
-42- Fuel injector #7
-43-Left HEGO. Found right above R HEGO in black 8 pin round connector.
-44-vacant
-45-BP sensor- middle pin in plug
-46-sig return- ECT, TPS, ACT, BP, EGR, STI plug
-47-TPS
-48-STI plug
-49-HEGO ground. Found in engine wiring harness. I will attach the metal ring to the intake when installing
-50-MAF
-51-vacant
-52- Fuel injector #8
-53-vacant
-54-A/C- I plan to delete
-55-vacant
-56-goes to the top pin on the TFI plug
-57-12V EEC power, also goes to 37.
-58- Fuel injector #1
-59- Fuel injector #2
-60- Ground. Same as pin 40.

 

[broncosbybart]

I have never heard this about the starter solenoid. I was hoping to stay away from a starter mounted solenoid and keep my current setup.

This project is being done on a MAF harness, as most swaps are.

the most desireable OEM5 mustang 5.0 harness to use are 89-93 (mass air), the 88 calif version is also mass air. All mustang 5.0 harness 86 & 87 are speed density. Every year of the mass air versions are different pinouts with some years having wire color changes for the same circuit. Also the EGO (heated oxygen sensor harness) is different from automatic to manual. It is imperative that you use the same year and trans type EGO harness to match up with the pinouts of the engine harness. One additional thing to remember on mass air versions is to use the late mustang diode protected starter solnoid to protect the ECM from back voltage. This is the most overlooked EFI wiring concern and can cause drivability problems that will NOT set any codes.

 

[brianstrange]

I am going to delete the salt and pepper engine harness connectors.

Be very careful doing this. I've done that many times, and you may have underlying corrosion that will prohibit soldering. Be prepared to use the following step to properly solder them: http://www.instructables.com/id/How-to-perfectly-clean-wires-in-minutes/

 

[brianstrange]

1) Pin 30 gets 12v+ on start, but before NSS. This way the computer is aware of a start attempt if the car is in gear, or NSS failed.

2) Pin 19 is fuel pump monitor. Just hook that up to the same wire that powers your pump. You don't have to run it all the way back to the pump.

3) OPTIONAL Pin 31, 32, 33 & 38:connect each to a 10K resistor, with "power in run" (37/57) supplying power. It will eliminate codes.