Electrical Wiring harnesses different in auto vs manual trans cars?

ggradtech

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Jun 17, 2016
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I know you can use an A9P ECM in an auto or a manual car, but you cant use an A9L in an auto. Is there a difference in the wiring harnesses? I want to try an A9L in my manual car, but dont want to fry anything. Is there is a difference in the wiring? How do you decipher which harness you have?
 
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Boostedpimp

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May 8, 2003
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If you use your a9l ecm with a car that has a auto o2 sensor harness you'll fry it. You have to either change the jumper on the harness or toss in the correct harness. If you go to PonyPerformance.com and look under the technical section you'll see the diagram you need.
 

ggradtech

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Jun 17, 2016
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Thanks for the info. I'll take a look at mine in the morning. When you "jumper" the wire as seen in the link, how do you do it exactly? I didn't see a color coded description though explaining which color wires are specific to auto vs manual trans O2 harnesses.
 

ggradtech

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Jun 17, 2016
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Thought I'd follow up. Took a picture of my O2 harness on the passenger side of the motor area. Mine is "pinned" or looped from #1-#6. Looking over the link and also a YouTube video, It looks like mine is a manual trans O2 harness. Can anyone confirm this for me? Thanks
 

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Mustang5L5

This is a big reason why I pulled it out
Mod Dude
Feb 18, 2001
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Without knowing the year of the car, we can’t confirm.

Also, there’s no reason to swap ecus. They are virtually the same. I was part of a thread years back where someone dissected the code and discovered very little is different in terms of engine tune.

Main difference is start circuit routing which is why the loop must be chNged
 

ggradtech

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Jun 17, 2016
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There is some info about using an A9P in a manual. It can cause idle-hang. They will certainly work. Ive only had A9P ems in my 2 manual trans cars. They both ran great with the A9ps installed. The only issue (both cars actually), is the slight "idle-hang". It comes down to a normal idle, but not as fast as it should. Is there any real data to support this theory? It's easily found if you search the topic.
 

Mustang5L5

This is a big reason why I pulled it out
Mod Dude
Feb 18, 2001
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Massachusetts
I’ve run into this when I converted my auto to a stick and left the auto ECU. There is no NGS on the auto trans harness so the ECU always thinks it’s loading up against a stall converter.

I finally converted to the a9L by repinning the o2 harness and added the trans harness with the NGS plug. The car ran beautifully after the swap. Never better
 

ggradtech

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Jun 17, 2016
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My car has a manual O2 wiring it seems. Besides the A9L, what other stuff would I need? Whats the trans harness with NGS plug? Thanks.
 

Mustang5L5

This is a big reason why I pulled it out
Mod Dude
Feb 18, 2001
31,500
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Massachusetts
There are 4 different o2 sensor pinouts and some of the info on the internet is incorrect, so I would double check that.

The trans harness is the main harness that runs from driver's kick panel over to the trans tunnel. Under the car, 3 pigtails come out of the trans tunney. The VSS, the NGS and the reverse lights. The auto harnesses are missing the plug for the NGS. This plug is wired in parallel with the NGS plug on the clutch pedal