O2 Harness

[Black1987]

I know there is a thread somewhere about the differences of O2 harnesses through the years.

Since I'm going to the correct 93 - 5.0 harness for my car. I begin to wonder if I need to go ahead and just order the matching 91-93 O2 harness for a manual, because I'm unsure of what is on the car now.

Any indication of color wires and/or pin layout? I know wires to the computer harness has some differences, but is there any indication on the O2 harnesses themselves?

 

[srtthis]

best place to start with that is the Tmoss site

 

[a91what]

This one?

Www.Veryuseful.com

 

[Mustang5L5]

Breakdown of harnesses is this

1987 to early 1988 harness for both 5spd and AOD (no jumper at all)
later 1988-1990 5-spd harness (jumper from pin 1 to pin 5)
91-93 5-spd harness (jumper from pin 1 to pin 6)
later 88-93 AOD harness (jumper from pin 5 to pin 6)


If you have a harness with a jumper, you can repin it. no need to buy another


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[Black1987]

Breakdown of harnesses is this

1987 to early 1988 harness for both 5spd and AOD (no jumper at all)
later 1988-1990 5-spd harness (jumper from pin 1 to pin 5)
91-93 5-spd harness (jumper from pin 1 to pin 6)
later 88-93 AOD harness (jumper from pin 5 to pin 6)


If you have a harness with a jumper, you can repin it. no need to buy another


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I'll try to check mine tomorrow. Is this jumper On each sensor connector under the car (44/45) or where it plugs into the engine harness (45)?

 

[Mustang5L5]

No, it's on connector 42 on your pic. It's located under the MAF next to the WOT relay.

Connector 44/45 connect to the o2 sensors under the car. 43 is the low oil sensor

The jumper actually has nothing to do with the o2 harness. Ford just chose that spot to jump the NGS circuit depending on transmission. They had some free pins on the connector

1987 cars may have wired the NGS differently, so the jumper and 3 extra wires on the body side harness may not even be present


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[Black1987]

No, it's on connector 42 on your pic. It's located under the MAF next to the WOT relay.

Connector 44/45 connect to the o2 sensors under the car. 43 is the low oil sensor

The jumper actually has nothing to do with the o2 harness. Ford just chose that spot to jump the NGS circuit depending on transmission. They had some free pins on the connector

1987 cars may have wired the NGS differently, so the jumper and 3 extra wires on the body side harness may not even be present


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So pin layout diagram? Assuming when looking at the top to bottom, it goes 1,2,3 etc, correct?

 

[liljoe07]

5 speed or automatic car?

 

[Black1987]

5 speed or automatic car?

5 speed

 

[liljoe07]

Pin it so the loop on the 02 harness connects the blue/yellow wire to the purple/yellow wire on the engine harness.

 

[Mustang5L5]

Looks like an AOD harness.


To repin it you'll need to pull that red plastic part out. Then you can swap the pin around. Might be easier on a bench


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[Black1987]

Okay so

And then

 

[Black1987]

Now @Mustang5L5 , above there was mention of blue/yellow to purple/yellow. If that was/is the case it would be one pin over.

Any clue

 

[liljoe07]

You can't always go by pin location. That's why I gave you colors.

 

[Black1987]

You can't always go by pin location. That's why I gave you colors.

So where does the purple/green wire in that pin go?

@jrichker

 

[Mustang5L5]

What are the colors of the three "free" wires on the engine side of the harness. 5 wires are for the o2 sensors and low oil sensor leaving three wires that get jumpered between 2 of the 3.

What are the corresponding colors there?


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[Black1987]

What are the colors of the three "free" wires on the engine side of the harness. 5 wires are for the o2 sensors and low oil sensor leaving three wires that get jumpered between 2 of the 3.

What are the corresponding colors there?


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I'll have to check when I get home, both the engine harness on the car and the one that I'm repairing (off the car) have the blue/yellow wire one pin over from what I jumped too.

The wire on the engine harness that goes to the pin I jumped to per the illustration went like a pinkish/faded cream color wire with a black line.

I'll let you know later tonight

Thanks for the feedback

 

[Mustang5L5]

Let me take a step back and make sure I pass along correct info. This is a 1993 Mustang, with a 5-spd transmission and 5-spd computer correct?

Can I ask why it appears you have a AOD harness on the car instead?

And what are the colors of the 3 wires that are on the current jumper, and the spot without any wire on the o2 harness?


At the end of the day,. you should check for voltage on pin 46 before cranking the engine over. Pull the ECU out, and put a DMM on pin 46 on the ECU harness and test to ground with the computer completely disconnected. You should not get any voltage when you test while cranking, or key on, and clutch in and out while cranking. If you do, the pins are incorrect.

 

[Black1987]

Let me take a step back and make sure I pass along correct info.

This is a 1993 Mustang, with a 5-spd transmission and 5-spd computer correct?

Currently I do not no the year of the harness in the car. It was modified to fit the 93 body harness, was done by someone else. I believe it was an 89 if I remember correctly.

The car is a five speed, as of right now has the A9L due to it would run fine for awhile with the A3M but then after I added new O2s it wouldn't make it about a mile and start breakup and back firing.

I just purchased a matching 93 5.0 harness. That had the chafing.

 

[Mustang5L5]

I'll share with you this photo, but do not use it as reference as I do not know what year harness this is referring to, so it could be different

Black connector #40 is the one to look at. You'll see there's a ground and power for the O2 sensors, and a signal wire from each o2 sensor. There's also a wire for the low oil sensor. The other 3 wires are what we are looking at.

Basically the point of the jumper is bridge the connection between pin 30, to the corresponding wire depending on if the car is a stick or 5spd. Make sense?