Neutral Safety switch

[freddyk70]

EFI in old mustang '92 A9 computer. Car runs great in neutral but won't accelerate up to speed at all, chokes and dies.

No neutral switch hooked up so I can't get codes when engine is running.

How can I clear the error to get the codes? Can I just coonect pin 30 and pin 46 to complete the loop?

Pin 30 Transmission Neutral Interface

Pin 46 Signal Return

I do have a T5 but I don't recall if it has the neutral safety switch on it I'll have to look when I get home. If it does, how do I hook that up? Pin 30 to one side and Pin 46 to the other?

Thanks for the help!

 

[liljoe07]

First is the car an original Auto car or 5 speed? It matters.

 

[freddyk70]

Engine is originally from T5 car. Computer - bought reconditioned one at Auto Zone for manual shift 1992 Mustang. It's an A9, but there were several to choose. I told the bozo behind the desk and he plugged it in his computer so figure out the one I needed.

I am seriously thinking this thing could be junk. Might try new ECM.

I am getting code 66 tho - mass air meter voltage below .4. Might junk the Abaco DBX meter and go back to a stock one, or maybe try a C&L heard good things about those.

Any thouights on my plan?

 

[LocoSway]

Computer is a A9 what? A9L, A9P, etc.

This matters because the A9L is for manuals and the A9P is for automatics.

 

[HISSIN50]

Joe's right on. Gotta have the last part of the catch code.

You also will probably want to explicitly note what factory trans was in the donor-wiring harness car (in case parts came from multiple cars). As Joe said, the autos and sticks handle Pin 30 differently (autos ground it to the solenoid and sticks go to sig return as I recall). If you used an auto harness with a manual (A9L) EEC, you will want to modify Pin 30.

Try a 94-95 Mustang MAF (they're all the same) if you have 19# injectors.

Did you ever unplug your MAF while doing diagnostics? That could generate a low MAF voltage code.

Good luck.

 

[Mustang5L5]

I'm getting the feeling this is a Automatic harness equipped vehicle with a 5-spd computer.

In which case you need to either put an Automatic computer in, or switch the O2 harness out to a manual trans o2 harness, or modify the harness

 

[freddyk70]

Using aftermarket harness. It was never specified whether auto or manual when I got the harness. This is an interesting point tho and one I never considered... but I'm not sure of the differences? The harness was missing several pins, which I added back like the neutral safety switch. But everything else just plugged right in.

Computer is A9L for manual shift 1992 5.0. Autozone special, rebuilt. I am wondering if it's junk after getting code 98 hard fault, sounds scary

To get codes, I tried to ground pin 30: to the body, to the key, to the negative battery post, that didn't work at all and I still got no codes.

Then I tried to connect pin 30 and 46 (signal return, read that in Ford Motorsport manual). That did work, kinda - But I still only get 2 codes 66 and 98.

Talked to a guy today who highly recommends making sure all grounds are good so I have to double check all that. He even says make sure no paint on engine where it's grounded, and to ground computer directly to battery. Can't remember if I did.

Thanks for all the input everybody!

I'm getting the feeling this is a Automatic harness equipped vehicle with a 5-spd computer.

In which case you need to either put an Automatic computer in, or switch the O2 harness out to a manual trans o2 harness, or modify the harness

 

[Mustang5L5]

Using aftermarket harness. It was never specified whether auto or manual when I got the harness. This is an interesting point tho and one I never considered... but I'm not sure of the differences? The harness was missing several pins, which I added back like the neutral safety switch. But everything else just plugged right in.

Well, i can't speak for the aftermarket harness, but the factory harness actually sends NSS through the O2 harness for some odd reason. Prob is that AOD's and T-5 cars use different pins on the harness for the NSS through the o2 harness. So using a automatic o2 harness sends the sig rtn back on a different pin than a manual o2 harness would....and has been known to fry the EEC


But i can't be sure because I don't really know how the aftermarket harness is wired up. Is is a custom job? Painless kit?

 

[liljoe07]

Doesn't matter what computer is used. An Auto 02 harness with a manual trans setup and working NSS circuit will fry the ECM. A9L,A9P ect.ect.

Easiest way to check, is with the ECM out. And do a cranking voltage check on PIN 30 and 46. If its set up like an Auto trans, PIN 30 will see 12v during cranking with clutch down. Assuming the NSS circuit is working as it should.