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Mustang5L5 -- The LMR harness (that you referenced in an above post) says it's for an 87-93. I am planning a T-5 swap into a 1986 GT with an AOD. Will this harness work with my 86 application? Anything else different with the 86 vs 87 and up? Thanks!

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Mustang Manual Transmission Harness (87-93) 5.0 - LMR
Use this 5.0 Resto 1987-1993 Mustang 5.0L manual transmission harness to repair your damaged or melted harness.
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So i must admit, i am much better with 87-93 wiring than pre-87 wiring. I do have an 86 EVTM so I can check this out later on.

I want to say that in this particular case the main difference is the connectors. I know this is true with 1985 wiring as it has a lot of unique 1-year connectors, but i'm not 100% sure on 1986. I'll dig into it later on when i can check out the '86 EVTM.


That particular harness (at least the 87-93 version) carries three circuits. 2 wires for the VSS. 2 wires for the backup light and 2 wires for the neutral safety which is only used on AOD cars. On the 5-spd cars the NSS is just jumpered out on the red/blue wire on post 2 and Ford relied on a clutch safety to prevent you from starting in gear.

I'll have to check later to see if the 86 cars are wired similarly, but I want to say they are and it's a connector mismatch. Sorry i can't give a more definitive answer just yet.
Thanks! I'm planning to start working on the T-5 swap this weekend and wanted to try to figure out the wiring ahead of time, but I might have to just dig into it when I tear it apart. I haven't seen any posts specific to the 86 year (maybe I haven't searched hard enough) for the T-5 swap and how to re-wire to make the clutch safety switch fully functional.
 

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Ok, looks like ford still routed the three circuits through the same harness like the 87-93 cars, but the location of the plug is different. It comes up the trans tunnel and connects center of the dash behind the center of the instrument panel(th is might mean dash) , not the kick panel.

black 8-pin plug, C350 on the wiring diagrams . Cannot locate a diagram showing the location.

for wire colors:

VSS: black/white stripe, Dark Green/white stripe
Backup lights: purple/orange stripe, black/pink stripe
Neutral safety: white/pink, red/lt blue

Unsure if the other two spots on the 8-pin connector are occupied, so possibly 6 wires in a black 8-pin connector. See if you can locate it under the dash. I’ll update if I find more info

still unknown if the 87-93 harness would work. Would need to see the 86 harness first
Here is a pic of the harness coming from the trans tunnel. Nothing was hooked up to the single black connector.
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How many wires are in that plug and what are the colors?

I see more than 6. Possible you already have the connection for the NGS?
8 Wires total. The wiring diagram should be close on the colors, but it's hard to tell because they are faded. For Example: "Black White" means Black wire w/ white stripe. The wires coming from the trans are on the left side; wires coming from the car-side are on the right side.
 

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I forgot a circuit.

So should be 8 wires.

2 for backup
2 for VSS

those match the EVTM.

the wire colors for the VSS don’t match up. There’s two for those. Then there should be 2 for the NGS on top of the t5. I can’t find those wire colors in the EVTM, but Ford did a terrible job diagramming that out on the 87-93 cars as well and the EVTM is actually incorrect.

anyway, it’s possible since your have 8 wires in that plug, that you might already have the plug for the NGS present. Have you gone under the car and verified if it is in fact there? My 88 aod car only had 6 wires in the harness so I had to swap to the 8-wire manual harness, but it looks like yours might not need to be changed.

ultimately that’s what drove us on this hunt right? Adding the correct harness for the NGS?
I will put it on a lift this weekend and see what connectors are there, and will report back - thanks!!
 

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I forgot a circuit.

So should be 8 wires.

2 for backup
2 for VSS

those match the EVTM.

the wire colors for the VSS don’t match up. There’s two for those. Then there should be 2 for the NGS on top of the t5. I can’t find those wire colors in the EVTM, but Ford did a terrible job diagramming that out on the 87-93 cars as well and the EVTM is actually incorrect.

anyway, it’s possible since your have 8 wires in that plug, that you might already have the plug for the NGS present. Have you gone under the car and verified if it is in fact there? My 88 aod car only had 6 wires in the harness so I had to swap to the 8-wire manual harness, but it looks like yours might not need to be changed.

ultimately that’s what drove us on this hunt right? Adding the correct harness for the NGS?
Yes, my goal is to have the 86 GT set up like factory, i.e., it will only start when the clutch is pressed to the floor.
 

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Yes, my goal is to have the 86 GT set up like factory, i.e., it will only start when the clutch is pressed to the floor.
Let me clarify, I want to wire it so it won’t start unless the clutch pedal is pressed in. I don’t care about it being in neutral to start. I’m at a loss without a wiring diagram, but I am guessing the clutch pedal safety switch on the clutch pedal is all I need hooked up and wired properly to accomplish my goal, correct?

Also, is the cruise control at all impacted by any of this wiring? My cruise works and I want to keep it working!
 

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The 5-spd cars bypass the NSS that is normally used on the AOD cars. It gets jumped out on the reverse harness pigtail. Red wire with blue stripe.

the connector on top of the T5 is called the NGS or nuetral gear switch. It’s not a nuetral safety. The 5-spd cars rely on a clutch starter safety switch and those plugs are tucked under the dash over near where the clutch pedal hangs. Just need to remove the jumper and plug them in.

the NGS May affect idle quality and cause a hanging idle on “some” cars if left disconnected. My car had this issue which was cured by plugging in the NGS. Other cars run perfectly fine without it.

since I’m all about keeping wiring and such as close to OE correct with little variation, I recommend putting in the effort to see what it would take to hook it up proper. I also typically recommend using a 5-spd ECU. Again some folks never have an issue with the aod stuff, but I did. I left the NGS unhooked and ran the aod ECU. Every once in a while I had hanging idle issues that I could never solve. Finally I swapped to the correct 5-spd wiring first and then an A9L and all that went away and the car has never run better.
I fully agree with trying to keep the wiring OE, which helps troubleshooting in the future. I will dig into this more when I get the EVTM manual I ordered. I should also look at the best ECU option because I want to avoid future problems. Also, I was thinking of staying with speed density, but could switch to mass air. I am trying to make this a good, reliable driver.
 

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I forgot a circuit.

So should be 8 wires.

2 for backup
2 for VSS

those match the EVTM.

the wire colors for the VSS don’t match up. There’s two for those. Then there should be 2 for the NGS on top of the t5. I can’t find those wire colors in the EVTM, but Ford did a terrible job diagramming that out on the 87-93 cars as well and the EVTM is actually incorrect.

anyway, it’s possible since your have 8 wires in that plug, that you might already have the plug for the NGS present. Have you gone under the car and verified if it is in fact there? My 88 aod car only had 6 wires in the harness so I had to swap to the 8-wire manual harness, but it looks like yours might not need to be changed.
Here is a picture of the two connectors that go to the AOD on my 86 GT - there are only six wires (in two connectors) running through the trans tunnel to the AOD. Wiring is as follows:
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Two Prong Black Connector: Green/White & Black/White
Four Prong White Round Connector: Black/Pink, Purple/Yellow, Red/Blue & Yellow/Pink

Do you agree that it looks like I need to get ahold of an 8-wire manual harness?
 

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I'd like to know the manufacture date of your 86'? Because it has the large connector harness plug for the AOD like from the early 80's up to 85' cars I thought. Maybe they extended the use of these connectors into early 86'. Is it an early in the year production 86'? I happen to have a T-5 wiring harness pig tail for that large plug connector if you end up keeping the harness that's in the car.
If the driver's door is original to the car (which I can't confirm because I have not owned it since new) it says it was manufactured on 09/86.
 

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See attached picture. Does this harness look like the NSS harness that I need to install for my T5 transmission (which replaces the existing AOD harness that is running to through the trans tunnel)? I don't have a wiring diagram for the harness.
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Here is a picture of the two connectors that go to the AOD on my 86 GT - there are only six wires (in two connectors) running through the trans tunnel to the AOD. Wiring is as follows:
View attachment 1092603
Two Prong Black Connector: Green/White & Black/White
Four Prong White Round Connector: Black/Pink, Purple/Yellow, Red/Blue & Yellow/Pink

Do you agree that it looks like I need to get ahold of an 8-wire manual harness?
To Clarify: Two wires are running to the automatic shifter handle. So there are 8 wires in the AOD harness plug in total, 6 are running to the AOD trans and 2 are running to the shifter handle.
 

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Here is the wire identification for the above harness

Rev = Reverse light switch
NSS = Nuetral safety jumper
VSS = speed sensor
NGS = Nuetral gear switch (top of T5)

View attachment 1092606
Thanks for the harness identification!

Here is a checklist of what I think I need to do from a wiring perspective to get the T5 to function properly in the 86 Mustang with speed density which formerly had an AOD, but am not experienced/knowledgeable enough to know if it is correct -- what am I missing? Assume the T5 trans, pedals, etc... are fully installed.

1. Replace AOD harness with a T5 harness (like in the picture). This assumes I have the correct T5 harness which I will need to verify.
2. Obtain a NGS (and install in the T5) and hook up the NGS connector in the T5 harness to the T5 Transmission.
3. Hook up VSS and Reverse connectors.
4. Find the connections for the starter clutch pedal switch & NSS, and plug them into the clutch pedal switch assembly.
5. Hook up the cruise control switch connector to the clutch pedal.
6. No need to touch the 02 harness with A9P or A9L if keeping speed density.
7. If using an A9P computer, there might be issues like hanging idle. But if using an A9L computer, there should be no hanging idle issues. Note: I currently have a used A9P that I could try out, but I don't have an A9L.
 

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you only need to do 1 and 2 if you are changing out from the AOD ecu to the 5-spd ECU.

Both AOD and 5-spd cars use the same VSS and such, so this should be an easy swap. 86-88 cars use the VSS only for cruise control. Mass air cars do have an ECU connection to the VSS so the wires need to be added to pin 3 and 6 when you do a MA conversion

For step 5, the wire should be present with a jumper on it clipped to the metal support bracket near the gas pedal. Just remove the jumper and plug into the cruise disconnect plug on the pedal assemble. I recommend making sure all the cruise components are present and properly installed before installing the pedal assembly.

For 6, the o2 sensor harness jumper is a 1988+ thing. It's not present on 1987 and from what I can see also not present on 1986.

Unknown for #7 regarding the A9P. It might hang, it might not. I found it did with the A9L until i hooked up the NGS on the T5 and the only really mine wasn't hooked up was because I missed up and forgot to install the little pin under the detent ball. I wasn' dropping the trans to install that without a better reason, so I lived with it. It did it infrequently enough that it didn't bother me. Adding the pin cured it completely.


I would simplify things a lot here. Disregard the MA swap for now.

You can keep your current ECU and just hook up the clutch starter interrupt switch and the clutch NGS, and hook up the reverse light and VSS (if equipped). That will get you a running and driving 5-spd car. This will get you up and running with minimal hassle. Might you get a hanging idle from time to time? Maybe. I did.

Now, to do it factory OE correct, you'll want to track down a 5-spd 1986 speed density manual ecu. Unknown if 87 and 88 can be used. 1986 won't have the O2 sensor harness jumper. From what i see in the EVTM, it's similar to 1987 is that there is no difference in how the autos and manuals are wired for pin 30. Swap that in, install the correct trans harness that has the provision for the NGS (or run 2 wires) and that's really all that's needed.

Later on, if you want to mass air swap. Use an A9L or other 5-spd ECU, repin for the MA, and add 2 wire for the VSS (pin 3 and 6 i believe) and the single wire for the fuel pump monitor.
Thanks, Mike. I super vote for simplification here.

Do you know if the attached photo of this VM1 will quality as a ECM for the 1986 speed density manual ecu? I bought it several years ago along with some other parts and just realized I had it.
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Now, to do it factory OE correct, you'll want to track down a 5-spd 1986 speed density manual ecu. Unknown if 87 and 88 can be used. 1986 won't have the O2 sensor harness jumper. From what i see in the EVTM, it's similar to 1987 is that there is no difference in how the autos and manuals are wired for pin 30. Swap that in, install the correct trans harness that has the provision for the NGS (or run 2 wires) and that's really all that's needed.
I like this OE correct option the best if I can make it work. Remember you helped me understand that there are 8 wires in the existing AOD harness connector inside the car and we identified (if I understand correctly) that there are 2 wires running from the connector to each of:

Rev = Reverse light switch
NSS = Neutral safety jumper
VSS = speed sensor
Automatic shifter assembly

Here is my question/confusion: If I run 2 new wires (instead of getting a T5 harness) to the harness for the NGS (neutral gear switch at top of T5), I will be adding the 2 wires to the existing AOD harness that runs through the trans tunnel, the 2 wires will go to the NGS on the trans, but where will they hook to inside the car?

It wouldn't make sense for these 2 new wires to run into the 8 pin connector in place of the wires that previously served the automatic shifter. I suspect this is where having a manual might help me out, but the more I read the more I it appears that the manual might not be that helpful.
 

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I forgot a circuit.

So should be 8 wires.

2 for backup
2 for VSS

those match the EVTM.

the wire colors for the VSS don’t match up. There’s two for those. Then there should be 2 for the NGS on top of the t5. I can’t find those wire colors in the EVTM, but Ford did a terrible job diagramming that out on the 87-93 cars as well and the EVTM is actually incorrect.

anyway, it’s possible since your have 8 wires in that plug, that you might already have the plug for the NGS present. Have you gone under the car and verified if it is in fact there? My 88 aod car only had 6 wires in the harness so I had to swap to the 8-wire manual harness, but it looks like yours might not need to be changed.

ultimately that’s what drove us on this hunt right? Adding the correct harness for the NGS?
When you swapped in the 8-wire T-5 harness, did you just unplug the AOD harness and plug the T-5 harness in? What year is the car you did the T-5 swap in?
 
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