Ford Mustang Forums banner
1 - 8 of 8 Posts

· Premium Member
Joined
·
43 Posts
Discussion Starter · #1 ·
Okay, I've come to a point where I am certain I want to install a Coyote in my 89 GT. I have read many articles on how and what to buy ect...
The question I have is once the engine is in, how do the accessories work? Meaning, what controls the windows, wipers, cc, flashers, defroster, lights? How are those things wired to work? Do you just supply power to the original PCM without the engine controls? Where does the old meet the new technology? This is literally not covered anywhere I can find!
Basics on the car, 89GT roller with no cooling system, fuel system, exhaust system or drivetrain. I have a Tremac TKO 600, tubular K-member installed, Full interior, perfect body.

Thanks in advance
 

· Registered
Joined
·
3,391 Posts
The computer doesn’t control a single thing you listed. You could have a car with no ECM or engine installed and as long as you have power to the ignition switch, most or all of those things you listed will function just fine, I’d need a wiring diagram to be more specific. The power coming from the ECU may supply those functions but at the end of the day, they just need power.

This site is your friend: Mustang FAQ - Wiring, Engine, Air Bag, ABS Home Page

Will tell you all the pre-existing wiring that exists in your fox that needs nothing more than 12v power to function as intended. Just have to start looking through the diagrams.
 

· Registered
Joined
·
25,635 Posts
Okay, I've come to a point where I am certain I want to install a Coyote in my 89 GT. I have read many articles on how and what to buy ect...
The question I have is once the engine is in, how do the accessories work? Meaning, what controls the windows, wipers, cc, flashers, defroster, lights? How are those things wired to work? Do you just supply power to the original PCM without the engine controls? Where does the old meet the new technology? This is literally not covered anywhere I can find!
Basics on the car, 89GT roller with no cooling system, fuel system, exhaust system or drivetrain. I have a Tremac TKO 600, tubular K-member installed, Full interior, perfect body.

Thanks in advance
As said

look at the wiring diagram for your '89 and see what is connected to the ecm for control, you will see not much
 

· Registered
Joined
·
332 Posts
Rip the ecu out and the engine harness. Not needed for any body function.

Under the hood connected to the starter soleniod relay, there’s one yellow wire (3 wires terminate into that yellow wire) that is power for the fuse block. There’s another black wire with a small breaker at the end, that’s power to power windows and locks. With those 2 powered you will have all body functions working.

The oil pressure and temp from the gauge cluster go directly out to the sending units on the engine. Speed is cable driven directly to the trans. Voltage gauge gets power from the fuse block and will work if the aforementioned wires are hooked up to power. Tach is the only thing you will need to tap into to work. I would have to look at a wiring diagram but off hand i believe its a green/red wire coming out of the cluster.

The fuel pump will need to tapped into. You can add a new relay for that. Or there’s a relay under the driver side seat. You can tap into the trigger wire and run it to accessory key on, to a manual switch, or depending on your control pack you can wire it in and have the coyote ecu control on/off times. If you have a Power By the Hour control pack they will have a fuel pump relay on the relay/fuse block already. You just run a 10awg wire from that directly to the fuel pump.

Electric rad. fans will need to setup to be triggered by the coyote ecu or you can wire in a relay and have it automatically come on with key forward acc power. But typically what ever aftermarket control pack you get will have a flying lead from a relay to provide power to radiator fan. Worst case there will be a fan trigger wire you can use to trigger your own relay. That way ecu is controlling on/off times.

A/C and heat will still work too. The only thing it wont do without the factory ecu is idle the car up and automatically turn the electric fans on when the compressor is turned on. Again you can use the 12v compressor signal to trigger the fan relay or an override relay to turn the rad fan on when compressor is turned on.

Obviously you wont have cruise control buttons working anymore. But thats it.
 

· Premium Member
Joined
·
43 Posts
Discussion Starter · #5 ·
Thank you guys so much for the responses! I happen to stumble upon PBH's website and videos..I just binge watched them all twice! Lol
It's allot clearer now and solidified the swap!
 

· Registered
Joined
·
1,782 Posts
A really handy item to pick up is the Ford EVTM for your car. Ebay is a good source for them. It's helpful to have a hardcopy of your vehicle schematics when you get into the electrical end of things.
1056168
 

· Registered
Joined
·
869 Posts
Just to add a little more, there are basically two wiring harnesses in the car, a body harness that controls what you listed and the engine harness. There are not many places where the two harnesses connect so if you find those places and tie them in where they need to go on your new engine harness, you will be in good shape.
 
1 - 8 of 8 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top