This is in the main engine harness. I just did a 5.0 to 5.8 swap and I have this plug left over with nowhere to put it. The original harness from the 5.0 was pretty chewed up and I got this harness for free and at first glance everything looked identical except much cleaner and everything plugged in fine but I have this plug left over so I am guessing either I am just not seeing where it goes or the original 5.8L it came from had something mine does not have. It is splitting out if the loom right with the A/C plug and is long enough to either go up to the intake tubes like maybe a air sensor of some type which my vehicle is not equipped with or it is long enough to reach several areas. What is it and is it hurting anything to not have it plugged in? Oh and supposedly this harness came from the same vehicle the computer came from both are for a 5.8L with E4OD. The engine starts but dies after a couple of minutes. Dies abruptly like the computer shut if off. SO hunting around for issues. Oh and its a two wire plug.

 

Looking at a 1992 wiring diagram they show a power steering pressure switch in that vicinity but that would mean my original harness should have had that plug right? And it does not. This is the absolutely only difference in the two harnesses I can find. If I dont need it I just need to know what to do with it. Tape it off or put a jumper wire on it or what? I am trying to find a picture of someone elses truck online with this plug but not having much luck.

 

Ok.. I think I have narrowed it down to a Incoming Air Temp Sensor which means the harness is newer than the computer because the computer is a speed density computer. Is it ok to just leave it hanging? That also makes me wonder what other issues I may have now. Do I need to pull this harness back off the engine and save it for when i switch to mass air?

 

I thought that the SD system had an intake air temp sensor in the intake manifold, just behind the distributer in the intake runner.
My first thought was an AC high pressure switch.

 

The wire colors would help to ID it.

 

I will have to look when I get home on the wire color Pretty sure one is black with a green stripe on it. Oh and how would the engine act without it plugged in?

 

SD should have an IAT sensor. On a Mass Air system, it would be integrated into the airflow meter.

 

Ok.. Then where would it be. I cant find one anywhere and the 5.0L I pulled out did not have this plug on the harness. Someone if you can, show me where this thing is plugged into. I cant find anything on the intake or tubes that is missing.

 

The IAT/ACT sensor was located in the lower intake manifold until ~1994. Ford moved it to the air filter box.

Old location:

Item marked as ACT

Closed-up:

Near intake manifold Runner # 6

If you have a MAF truck the IAT/ACT is located at the air box. Try looking on the side facing the firewall.

 

On MASS air system the sensors are near each other but not the same item:


/

 

This may help on the plug:


Note the Power Steering switch plugs wires are a gray wire with a red stripe and a yellow wire with a light green stripe.
/

 

That is the mass air setup. My truck is Speed Density so The air box looks totally different. Mine looks just like the one pictured and the only holes in the housing are for the crank case vent coming from the oil filler neck.

 

Ok.. I can see what your talking about and I have a plug already plugged into that boss. Soooo.. That again leaves the question of "What is this plug for? Here is the picture I took of the engine partially installed and the harness on it and you can clearly see the air temp sensor plugged in to something. And that other wire is just laying there.

 

Did you look at the diagram in post #11 above.
Looks like it may be the Power Steering switch plug.

 

Yes I did look at the diagram and I dont have that plug on my power steering pump, so if that is what the plug is for I am missing that feature on this power steering pump. Not sure I have ever seen that but if that is what its for then thats easily fixed with a trip to the salvage, However it still begs the question as to whether this harness is newer than my truck and if it is for a mass air truck in which case are my injectors now wired wrong? Or is anything else wired up wrong that may **** off the truck. When it was started the gauges were acting crazy, The Tack stayed above 2K rpm when the engine clearly wasnt that high, the volt meter was jumping all over, the oil pressure stayed at the bottom (which I may have a bad sender, i had to use a old one I found laying around the garage) and the engine seemed sluggish, But my timing light would not work so I need to get a working one and set the timing correct. I did it by ear. Also the truck would just shut off abruptly after it ran for a couple of minutes. Not a stumble and die. It just cut off like you turned off the key but would re start after.