Engine **FIXED** Code 67 preventing KOER test... but clutch is pressed and A/C is deleted??

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Dan02gt

mazing how much gas smell came from that tiny hole
10 Year Member
Mar 2, 2003
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So I had a weird issue with mine a few years ago and spent days troubleshooting why the system wouldn’t work correctly. I determined it was a damaged wire coming off of pin 46 somewhere in the wiring harness. I fixed it by clipping the wire coming out of pin 46 a few inches away from the computer connector and ran a new wire that I connected to the neutral sensing switch connector that is in the center console for the auto cars. This fixed my problem. If I ever pull the dash out I’ll go through the wiring until I find the issue with the original wire.
 

TomOsiris

Member
May 19, 2019
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So I had a weird issue with mine a few years ago and spent days troubleshooting why the system wouldn’t work correctly. I determined it was a damaged wire coming off of pin 46 somewhere in the wiring harness. I fixed it by clipping the wire coming out of pin 46 a few inches away from the computer connector and ran a new wire that I connected to the neutral sensing switch connector that is in the center console for the auto cars. This fixed my problem. If I ever pull the dash out I’ll go through the wiring until I find the issue with the original wire.
Aren't there other wires that also ground thru pin 46 though?
Wouldnt cutting that wire and going straight to the neutral switch lose your ground for everything else, ECT, TP, ACT, ?

Or did you just like T-tap into the wire and connect it as a secondary?
88-91_5.0_EEC_Wiring_Diagram.jpg
88-91_5.0_EEC_Wiring_Diagram.jpg
 

Mustang5L5

Put lubricant all over the balls
Mod Dude
Feb 18, 2001
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Aren't there other wires that also ground thru pin 46 though?
Wouldnt cutting that wire and going straight to the neutral switch lose your ground for everything else, ECT, TP, ACT, ?

Or did you just like T-tap into the wire and connect it as a secondary?


You aren't necessarily clipping it out in the sense of elinimating it. You are just splicing in another leg for the circuit that the grounding circuit can use to complete. In other words, if you identify that one section of your wiring is damaged, you connect the new wire at a god known point ahead of the damage, and behind it.


To go back to that wiring diagram which is pretty marked up at this point. Lets say the wire was broken in the big red splotch and you lost the connection there. You would tap the new blue wire in at two known good points and just go around the break. See how the path of the blue wire adds an additional parh for the circuit to complete, but doesn't interfere with the other sensor taps for pin 46.

1656088116462.png
 
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TomOsiris

Member
May 19, 2019
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You aren't necessarily clipping it out in the sense of elinimating it. You are just splicing in another leg for the circuit that the grounding circuit can use to complete. In other words, if you identify that one section of your wiring is damaged, you connect the new wire at a god known point ahead of the damage, and behind it.


To go back to that wiring diagram which is pretty marked up at this point. Lets say the wire was broken in the big red splotch and you lost the connection there. You would tap the new blue wire in at two known good points and just go around the break. See how the path of the blue wire adds an additional parh for the circuit to complete, but doesn't interfere with the other sensor taps for pin 46.

1656088116462.png
ok this definitely makes sense to me.
in the post above when he said "clipping" I thought he literally meant cutting the wire at the ECU and running directly to the sensor.
I might end up doing something similar temporarily, but I'm pretty meticulous so I assume I will have to pull the dash and chase the harness, but not during driving season.
That can wait until winter.
Thanks again, I will be diving into the car deep this weekend, wish me luck!
 

Dan02gt

mazing how much gas smell came from that tiny hole
10 Year Member
Mar 2, 2003
883
431
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Aren't there other wires that also ground thru pin 46 though?
Wouldnt cutting that wire and going straight to the neutral switch lose your ground for everything else, ECT, TP, ACT, ?

Or did you just like T-tap into the wire and connect it as a secondary?
88-91_5.0_EEC_Wiring_Diagram.jpg
88-91_5.0_EEC_Wiring_Diagram.jpg
You are correct. I didn't have a wiring diagram in front of me when I made that post. I didn't cut 46, that's the signal return and cutting it would cause a ton of issues. I cut the wire coming out of pin 30, capped the harness side of the wire, and connected my new wire to the wire coming out of the computer connector. You could just use a T tap if you wanted to. My new wire runs to the connector that is in the center console and used for the auto cars and is part of the system. I used a T tap on it there.
 
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TomOsiris

Member
May 19, 2019
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You are correct. I didn't have a wiring diagram in front of me when I made that post. I didn't cut 46 that's the signal return and cutting it would cause a ton of issues. I cut the wire coming out of pin 30, capped the harness side of the wire, and connected my new wire to the wire coming out of the computer connector. You could just use a T tap if you wanted to.
Thanks for the clarification.
I am going to test for continuity from the clutch switch wires back to pins 30 and 46, respectively.
I highly doubt BOTH of them are broken/disconnected, so I should be able to get away with a jumper wire setup similar to yours until I can diagnose the issue hiding somewhere in the harness..
 

TomOsiris

Member
May 19, 2019
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Damage risk is low since we are dealing with grounds here, but my worry is false continuity readings through the ECU throwing off what you are trying to chase down.

I do have a spare A9L on the shelf. I can confirm in a bit that 30 and 46 are normally open.
Update - codes are fixed!

After getting some good advice here I spent the weekend testing continuity to and from the ECU and the various switches shown in the diagram.
However, what is not shown in the diagram is that pin 30 also connects to the o2 harness, where there is a jumper wire that loops back into itself in few different ways for either a t5 or AOD transmission.

That is why some people had a code 67 after swapping T5 to AOD, or vice versa.

I tested everything there and it seemed ok, so I reconnected and pulled the codes again just out of curiosity.
no code 67!

I should also mention the reason why it was so important for me to get rid of code 67, this code will prevent you from running KOER tests, which I needed to do test and eliminate some other issues I was having (code 41/91, lean readings at both o2 banks)

Well, after reconnecting the o2 harness, not only was code 67 cleared, but the o2 codes were gone as well!
I have determined that although the o2 harness was connected, it was not fully seated to the point where the clip would lock it together, and therefore the connections were not 100% and sending inconsistent signals back to the ECU.

Big thanks to anyone who posted here to help, as going through the process of recommendations I received is what led me to this fix.
Glad to be back out on the road with confidence.
 

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wbrockstar

Member
Mar 31, 2010
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You aren't necessarily clipping it out in the sense of elinimating it. You are just splicing in another leg for the circuit that the grounding circuit can use to complete. In other words, if you identify that one section of your wiring is damaged, you connect the new wire at a god known point ahead of the damage, and behind it.


To go back to that wiring diagram which is pretty marked up at this point. Lets say the wire was broken in the big red splotch and you lost the connection there. You would tap the new blue wire in at two known good points and just go around the break. See how the path of the blue wire adds an additional parh for the circuit to complete, but doesn't interfere with the other sensor taps for pin 46.

1656088116462.png
You're great at explaining things with easy to understand analogies/ visual reference.Thats up there in Jrichker territory.

I was a nuclear missile technician onboard SSBN submarines & studied/ applied electronics daily,but the instructors in SWSE (strategic weapons systems electronics) school & the weapons officer(s) onboard went completely by the book with only one means of describing a particular problem/ circuit.The learning curve was tough at times with the Navy's method.

Great job man
 
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wbrockstar

Member
Mar 31, 2010
41
5
18
Update - codes are fixed!

After getting some good advice here I spent the weekend testing continuity to and from the ECU and the various switches shown in the diagram.
However, what is not shown in the diagram is that pin 30 also connects to the o2 harness, where there is a jumper wire that loops back into itself in few different ways for either a t5 or AOD transmission.

That is why some people had a code 67 after swapping T5 to AOD, or vice versa.

I tested everything there and it seemed ok, so I reconnected and pulled the codes again just out of curiosity.
no code 67!

I should also mention the reason why it was so important for me to get rid of code 67, this code will prevent you from running KOER tests, which I needed to do test and eliminate some other issues I was having (code 41/91, lean readings at both o2 banks)

Well, after reconnecting the o2 harness, not only was code 67 cleared, but the o2 codes were gone as well!
I have determined that although the o2 harness was connected, it was not fully seated to the point where the clip would lock it together, and therefore the connections were not 100% and sending inconsistent signals back to the ECU.
Oh yeah,many Foxbody owners have felt the pain of that notorious jumper wire on the o2 sensor harness.
It has cooked thousands of ECU's over the years by being in the wrong terminal on the harness plug,for the ECU application.

The hood light harness plug has also cooked a bunch too,by mistakenly being used instead of the sti terminal to initiate a code scan.

Both of the above instantly fries pin 46's trace on the ECU,which basically creates a open in that circuit.Every component that's tied into that circuit fails to work or works incorrectly.Every sensor that has a signal return wire will fail to give correct readings.
 
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Mustang5L5

Put lubricant all over the balls
Mod Dude
Feb 18, 2001
39,486
15,332
224
You're great at explaining things with easy to understand analogies/ visual reference.Thats up there in Jrichker territory.

I was a nuclear missile technician onboard SSBN submarines & studied/ applied electronics daily,but the instructors in SWSE (strategic weapons systems electronics) school & the weapons officer(s) onboard went completely by the book with only one means of describing a particular problem/ circuit.The learning curve was tough at times with the Navy's method.

Great job man


Thank you sir. I appreciate it :nice:
 

limp

wrap a little cheese around it and its a done
Oct 4, 2020
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You're great at explaining things with easy to understand analogies/ visual reference.Thats up there in Jrichker territory.

I was a nuclear missile technician onboard SSBN submarines & studied/ applied electronics daily,but the instructors in SWSE (strategic weapons systems electronics) school & the weapons officer(s) onboard went completely by the book with only one means of describing a particular problem/ circuit.The learning curve was tough at times with the Navy's method.

Great job man
Based on your explanation of doing it ONLY one way on a Nuke, I would think that would be best dealing with nuclear missiles and a boat that goes under the water..... LOL
You caught me watching Red October.......