Help, Please. 12 Volts At Pin 46

millertime187 · Jan 29, 2015

Ok I have been chasing this problem for a few weeks now. I have a 1988 GT that was a Auto car switched to a 5 - speed. When I tried to pull codes I figured out my A9L computer had a fried trace. I have fixed that. Found it still had the auto O2 harness in it, bought a new manual one. But I still have 12 volts at pin 46 on the computer plug. I have checked all the grounds. The car is a mass air car. I really need some CLEAR direction on what to try next. The car ran fine before I started this, but I want it to be right. Any help is appreciated!!! Thank you in advance

jrichker · Jan 30, 2015

Just for reference, check the part numbers on your harness against the part numbers on the diagram below.

millertime187 · Jan 30, 2015

I purchased this one,

http://pages.ebay.com/link/?nav=item.view&id=230932341980&alt=web

jrichker · Jan 30, 2015

If you have multiple threads on a similar topic, ask the moderators to merge your threads. It is very difficult to keep up with what has already been posted. That helps prevent chasing the same rabbit multiple times.

There is no guarantee that it is compatible with the 5 speed car. Check the part number that is on the current harness against the part numbers on the diagram.

You need to have purchased an O2 sensor harness from Ford, Ford Racing or from a junkyard and check to see that it was
E8ZZ-12A690A or E8ZZ-12A690AA

Some review....

O2 Sensor harness interchange and modification

Originally Posted by 302EFI

Revised 16-Oct-2011 to add O2 sensor harness warnings
The wires for the 02's and low oil did not change throughout the years, they are all in the same place.
The main ones you need to worry about are (on the harness end (ECU) that plugs into the 02 plug) is:
\- 1. Lightblue / yellow
- 2. White / Purple
- 3. Purple / Yellow
The White/Purple & Purple/Yellow gets looped for a automatic ECU
The Purple/Yellow & Lightblue/Yellow for a manual ECU

Not all wires are shown for clarity and simplicity

See http://forums.corral.net/forums/gen...manual-auto-differences-year-differences.html for more O2 sensor wiring harness info

Basic premise to use with transmission swaps:
Only run a 5 speed trans O2 harness with an A9L. Do not run an Auto O2 sensor harness with an A9L. Doing so will damage the computer’s internal signal ground.
Only run an Auto trans O2 sensor harness with an A9P in a car that has an Auto trans. Using a 5 speed trans O2 sensor harness with an Auto trans will cause no crank problems.
See http://www.stangnet.com/mustang-forums/749974-computer-issue.html#post7490537 for Joel5.0’s fix to the computer internal signal ground.

The 4 cylinder O2 harness uses 4 wire O2 sensors. It won’t work correctly without modifying it.

millertime187 · Feb 6, 2015

Ok, I have been reading like crazy. Yes I had another post but it was directed toward another problem that turn into this. I truly don't think it's my O2 harness giving me my problem. The jumper wite is correct with the two wired it needs to jump. Plus I can un-hook the harness and still have voltage to pin 46. I think I have something else going on, but I can't figure it out for the life of me. My new thinking is its in the tranny harness maybe. That could supply voltage to pin 30. The auto natural safety switch is bypassed. Not sure what that that will do. I have a couple pictures of my tranny bypass, and the clutch connecters. Any other advice will be great full. Please and thanks.

Aod bypass

O2 harness jumper

Clutch connecters, is there something I need to do here?

Car will run, just my trace fry's on pin 46 causing limp mode, and no code reading.

jrichker · Feb 6, 2015

Car is now a 5 Speed, T5 - Yes/No/Other?

Does the car have an alarm or did it have remote start?

If you disconnect the NSS switch harness from the NSS switch on the transmission turn the key to crank, do you see 12 volts on any of the NSS switch harness pins?

See item #6 on the drawing below for a T5.

millertime187 · Feb 6, 2015

Car is now a 5 - speed car. It was originally a AOD. No alarm, and I don't think the clutch was ever hooked up. It still has the auto jumper on the clutch switch? It still has the auto tranny harness in it with the NSS bypassed next to tranny. item 6 is just hanging there. I just changed the tranny and the old t-5 was a early 80 ' s one so it didn't have a NSS. The new tranny is a t-5 like in picture but the only thing hooked to it is the speedo and the plug at the speedo cable.

So I'm thinking the problem is my auto tranny harness. Is there something else that needs to be jumped on the auto harness? Right now it just NSS for auto is tied together.

I really appreciate your time and help jrichker. Thank you very much. I hope to figure this thing out.

I have also read on people just grounding pin 30 at the computer? I have debating on that but don't really wanna go that route.

Thanks again man!

jrichker · Feb 6, 2015

Disconnect the transmission harness from the pigtail on the T5.
Check to see if you find 12 volts on either pin of the transmission harness . Us the transmission case for the ground.

millertime187 · Feb 6, 2015

The pigtail you speak of is the plug that hooks to the speedo gear?

millertime187 · Feb 6, 2015

Ok, I check both wires that hook to the speedo cable, no voltage. The NSS has no voltage. Only voltage I found was for the reverse lights

liljoe07 · Feb 6, 2015

Unplug 02 harness, and check for voltage at PIN 46.

jrichker · Feb 7, 2015

millertime187 said:
The pigtail you speak of is the plug that hooks to the speedo gear?

Wrong wires - see item #6 on the T5 drawing I posted.

millertime187 · Feb 7, 2015

liljoe07 said:
Unplug 02 harness, and check for voltage at PIN 46.

I still get 12 volts with it unhooked

millertime187 · Feb 7, 2015

jrichker said:
Wrong wires - see item #6 on the T5 drawing I posted.

I have the auto harness, so the item 6 is just hanging from tranny, so it won't have any volts. It's not hooked up

jrichker · Feb 7, 2015

The auto harness is probably the problem.

EDIT: Without the transmission NSS harness plugged into the NSS switch on the transmission, you will have a code 67 and probably an idle problem as well.

liljoe07 · Feb 7, 2015

millertime187 said:
I still get 12 volts with it unhooked

Now unplug the trans harness and test again.

millertime187 · Feb 7, 2015

Ok, I stall try this today!

millertime187 · Feb 7, 2015

http://pages.ebay.com/link/?nav=item.view&id=271753857054&alt=web

I found this one on ebay. My thing is the I belive the jumper you may be talking about is on the clutch switch conector. I see a jumper on this one too but I belive that's to jump a Auto NSS. Correct me if I'm wrong.

This is the jumper at the clutch connector. I belive it's the factory jumper for auto. Would this be giving me my 12 volts?

Give me a couple hours and I'll get out there and disconnect the tranny harness and check for voltage again. Then I'll pull that jumper at clutch and check too if I still get voltage.

Again thank you guys for the help. I feel like I'm narrowing it down now. I'm just trying to get her right. She's worth it, I love stangs.

liljoe07 · Feb 7, 2015

That jumper is just for the starter solenoid control. It should be connected to the clutch switch, so the pedal has to be down in order to start the car. Its jumped in an auto setup because the Auto uses the NSS switch on the trans to do the same thing. Plus there is no clutch switch. Granted that may be where the 12v is coming from, but you need it jumped to start the car, or hooked to the clutch switch. Either one will give the same results. Regardless, that plug has to have 12v going through it to for starter engagement.

millertime187 · Feb 7, 2015

Ok, I have the O2 harness, tranny harness, and that pedal jumper unhooked. I'm still getting 12 volts to pin 46???

She doesn't like being sick, she wants to ride again!!!

Thanks again guys

Help, Please. 12 Volts At Pin 46

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