Electrical AOD to T5 swap code 67, etc

1970machwon said:

Hey all, I did an AOD to T5 swap earlier when my auto trans crapped out shortly after a rebuild, and i just recently begun to check codes and ended up getting a Key on engine off code 67 along with many other emissions related codes (previous owner yanked it all). I did the test with clutch pressed down, neutral, A/C off. I’m trying to figure out if i did something wrong electrically during my swap. I’m running a 1987 harness that has been converted to MAF, with an A9P computer, and I have an all new clutch safety switch along with most of the other manual trans swap goodies. My car has an idle surge and has a tendency to stall when the clutch is pressed in while driving at a high RPM. Having the AC on makes the issue a lot worse with added load. These driveability issues could be unrelated but I’ve heard some people just have weird symptoms.
Where do i begin to look to troubleshoot this code? Was there anything that needed to be repinned at the harness with a trans swap? I’m unsure about the whole o2 harness thing as well. Do i need to do it to my car if i have all AOD electrical wiring/computer?
I realize this is a bit of a text dump, I’ve just been fighting issues for a while and im trying to give as much info as possible. Thank you!

Click to expand...

Mustang5L5 said:

There are two switches that would contribute to a code 67. One is on the clutch pedal, and the other is on the transmission.

WHen a car is swapped over to a 5-spd, the trans harness should be changed out as the AOD harness does not have the provision to hook up the NGS on top of the T5. You can either buy a new harness, or just add two wires and tie into the harness at the drivers side kick panel.

Mustang Transmission Wiring Harness; Manual (87-93 5.0L Mustang) - Free Shipping

FREE SHIPPING! Restoration Repair. Your Mustangs transmission wiring harness is exposed to heat, wear, road debris and the elements on a daily basis, all of whi

www.americanmuscle.com

You should also really consider swapping to a 5-spd ECU as well. I know many people say it's not necessary, but you will get some odd, quirky behavior from time to time (hanging idle for example) with the AOD ecu.

1987's do not have a look on the O2 harness that needs to be repinned. Take a look to verify this.



Really, when performing an AOD to 5-spd swap, the following electrical items should be done. I know some will disagree, but this would be how it would be done from the factory so IMHO it's the correct way to do the conversion

• swap to 5-spd ECU
• Repin O2 harness (if applicable. 1987 and early 1988 do not have the jumper. Verify no voltage on pin 46 before hooking up 5-spd ECU)
• Swap to manual trans body harness which has provisions for NGS on top of T5

Of course, you'll want to test the switch on the clutch pedal. Usually if the starter safety is working, the switch is working in terms of triggering the contacts for the NGS plug on the clutch switch. You can always unplug it and jumper it with a 5A blade fuse for testing purposes.

Click to expand...

Mustang5L5 said:

No, there is no Nuetral Safety in the sense of preventing in-gear starts on the manual cars. The Neutral safety is on the AOD cars only and jumped out the 5-spd cars.

The switch on top of the T5 does tell the ECU that the car is in neutral vs in gear, and is wired in parallel with the switch on the clutch pedal. The purpose behind this is to tell the ECU there is no load on the engine (because trans is in neutral or clutch is in) and may affect idle strategy.

You might want to do a little testing to determine if these switches are functional. Back when i had my AOD ecu in my 5-spd swap, i was able to clear the code 67 by keeping the clutch pedal pushed in.

On the clutch are two plugs. A brown one with a red/blue wire. This one is the clutch safety for the starter. The clear/white one is the NGS circuit. If you unplug this and put a 5A black fuse in it, it should close the circuit. At this point dump your codes and see if the code 67 is eliminated.

Click to expand...

Mustang5L5 said:

I assume it’s working in term of preventing the car from starting without the clutch pressed in?

Let me find a wIring diagram. With that jumped out your code 67 should have cleared. I may have to post tomorrow so if I don’t just reply so I can get a reminder

Click to expand...

Mustang5L5 said:

Pay no attention to the wire colors as this is the 1990 wiring diagram. But the wiring method applies. Autos and manuals are wired different.

do this as just a test. Pin 30 should have continuity to ground when you depress the clutch or put the trans in nuetral. You can backprobe the pin with a DMM and touch the other probe to a good ground. Kick in the clutch and see if you have continuity at that point.

you may have one or the other not making a connection

you should be able to do this without disconnecting the ECU, but it would prob be best to disconnect it given the cost of these units these days
View attachment 682228

Click to expand...

Mustang5L5 said:

Pay no attention to the wire colors as this is the 1990 wiring diagram. But the wiring method applies. Autos and manuals are wired different.

do this as just a test. Pin 30 should have continuity to ground when you depress the clutch or put the trans in nuetral. You can backprobe the pin with a DMM and touch the other probe to a good ground. Kick in the clutch and see if you have continuity at that point.

you may have one or the other not making a connection

you should be able to do this without disconnecting the ECU, but it would prob be best to disconnect it given the cost of these units these days
View attachment 682228

Click to expand...

Mustang5L5 said:

You don’t want to test voltage. You want to test for continuity to ground at pin 30.

when you close the loop by either shifting the trans to nuetral or kicking the clutch in, you should have continuity with ground. If you set the meter to continuity and backprobe pin 30 and a good ground connextion, you should get a connection with either switch closed

make sense?

Click to expand...

Mustang5L5 said:

You don’t want to test voltage. You want to test for continuity to ground at pin 30.

when you close the loop by either shifting the trans to nuetral or kicking the clutch in, you should have continuity with ground. If you set the meter to continuity and backprobe pin 30 and a good ground connextion, you should get a connection with either switch closed

make sense?

Click to expand...

1970machwon said:

Does anyone know where these wiring connectors hook to? The smaller brown connector doesn’t seem as important, it’s located behind the glove box about where the fuel door button is. I originally had it plugged into the fuel door release but found that it doesn’t belong.

The larger gray connector behind the radio area seems like it could be causing my code 67 because the wiring color (2 Black/White and one Green/Yellow) leads me to believe it’s used to connect the NSS to the ECU. I found that the gray connector for the fuel door (right side gray plug in photo) fits perfectly into this connector, but connecting the two blew the fuse I had jumpered in the NSS circuit and made the fuel door release disengage every 10 seconds or so, so I found out that belongs on the fuel door release instead.
Please someone help me, this wiring is driving me insane lol

Click to expand...