Drivetrain 91-93 Four Cylinder Five Speed Cars - No Neutral Gear Switch (NGS) Wiring

[AeroCoupe]

Went through the T5 and have it back in the car and I decided to finally look into why the NGS has no place to plug in on the car. After some digging around what I am understanding is the four cylinder T5 cars starting in 91 no longer have the NGS. My car was originally a four cylinder that I swapped back in 2002 so I now understand why there is no connection.

I bought a new transmission wiring harness from Ron Francis that has the NGS wiring in it but I wanted to make sure this is plug and play. I looked through my EVTM and the wiring diagrams I have for the car and it appears that all I need to do is unplug the old harness at the driver kick panel and plug the new one in.

Does anyone have knowledge on this or done the swap and is it this easy?

 

[AeroCoupe]

A little more information on how the ECU uses the NGS in its strategy (copied from a post over on foureyedpride.com):

That switch (on the top forward part of the T5's cover) is actually called the Neutral Gear Switch (NGS) by Ford and has a very specific purpose - both during normal operation of your car and during EEC diagnostic testing. It does not have anything to do with starting circuit.

There is a second switch on the passenger side of the pedal assembly which is the switch that kicks the cruise control out when the clutch is depressed.

*Side note - the switch on automatic transmissions is called the Neutral Safety Switch (NSS) by Ford. Do not confuse the terminology of the two as the NSS is wired into the starting circuit.

If you have a manual trans car the 'safety' switch for the starter is located on the driver side of the pedal assembly. This is the Clutch Safety Switch (CSS) and it has two plugs. The black plug is part of the starter circuit and the clear / white plug is part of the NGS wiring. The clutch must be depressed for the starter to operate (regardless of whether the trans is in gear or neutral).

The NGS circuit consists of the NGS switch in the top plate of the T5 and the clear / white plug side of the CSS switch. These switches are wired in parallel and are to signal the EEC as the when the engine is under load or not. The contacts on the NGS are closed when the trans is in neutral and the contacts in the CSS on the clutch pedal are closed with the pedal depressed (clutch disengaged). Closure of either switch signals the EEC that the engine is not under load and the EEC responds by adjusting idle speed, injector pulse width, etc. to assure smooth idle and/or idle down. Yes, this signal is sent every time you step on the clutch pedal - even momentarily while shifting gears. The EEC-IV responds to changing engine loads in milliseconds.

The failure (or disconnection) of either of these switches is actually planned for by Ford as failure usually means it will be open. Open tells the EEC that the car is under load. The NGS circuit arrangement and EEC program strategy is such that it is better for the EEC to think that it is under load when it's not. So theoretically you could remove/disable both switches in the 'open' condition and your car would probably run about the same. Perhaps there would be a bit more idle than you would otherwise need being the EEC strategy would be seeing under load conditions.

But wait, Ford's programming engineers have a small trip wire built into this circuit. In order to run the KOEO EEC-IV self-diagnostic test the EEC must be signaled that the engine is disconnected from the drivetrain (i.e. same as not under load with the engine running). To do this at least one switch must be 'closed' (i.e. trans in neutral or clutch pedal depressed). If the EEC does not get this signal while in the KOEO routine it will create a code 67 and will not let you proceed to KOER tests. So if your trans mounted NGS has failed - and failed 'open' - then you would need to rely on the clutch switch to create the required circuit connection during KOEO/KOER. You need to consider this as it can be a real pain to perform KOEO/KOER test while sitting in the driver seat with your foot on the clutch pedal (although it can be done if you are getting codes by reading MIL flashes, but only on vehicles that have a MIL lamp (89+???).

 

[Mustang5L5]

Went through the T5 and have it back in the car and I decided to finally look into why the NGS has no place to plug in on the car. After some digging around what I am understanding is the four cylinder T5 cars starting in 91 no longer have the NGS. My car was originally a four cylinder that I swapped back in 2002 so I now understand why there is no connection.

I bought a new transmission wiring harness from Ron Francis that has the NGS wiring in it but I wanted to make sure this is plug and play. I looked through my EVTM and the wiring diagrams I have for the car and it appears that all I need to do is unplug the old harness at the driver kick panel and plug the new one in.

Does anyone have knowledge on this or done the swap and is it this easy?

Yes, that's all there is to it. 4cyl cars and AOD's don't have the NGS plug. So when i converted my AOD to a 5-spd and used an A9L, i swapped the trans harness out to one from a 5-spd and you just unplug at the kick panel and plug it in. The wires for the NGS are present on the body side harness.

If you want to verify, you can unplug the corresponding NGS wire from the clutch switch and test for continuity across the two pins as you pull the trans in and out of gear.

But that's all it took for me to add it

 

[AeroCoupe]

Thanks! Was pretty sure and was hoping to get confirmation.

 

[Boostedpimp]

Yes, that's all there is to it. 4cyl cars and AOD's don't have the NGS plug. So when i converted my AOD to a 5-spd and used an A9L, i swapped the trans harness out to one from a 5-spd and you just unplug at the kick panel and plug it in. The wires for the NGS are present on the body side harness.

If you want to verify, you can unplug the corresponding NGS wire from the clutch switch and test for continuity across the two pins as you pull the trans in and out of gear.

But that's all it took for me to add it

I agree, I had to do the exact same thing with a 93 4 cylinder coupe I fully converted.

 

[AeroCoupe]

Thanks for the reply as that harness was not cheap new so I am glad its just a plug and play. Still too cold here to mess with tearing the car apart for all of this but I think I have all the harnesses to replace the aging ones and correct the NGS issue.

 

[Robinson]

I will study this but my 1993 4cy is auto, this thread addresses manual t5 4cyl cars that don’t have plug for ngs because they didn’t have this plug from factory.. but my 4cyl is a original auto car and I will be converting to t5 , so maybe I have this plug in passenger kick panel I will see .. ford did so much changing up and I really see no rhyme to reason, only confusion and lots of that but I will get it because it is what I do. Ron Francis does sell the t5 manual transmission harness and so does lmr but again where does it plug ona 1993 4cyl auto car once I convert to manual and 5.0? I haven’t looked yet but I will be pulling kick panel and seeing if there is a empty plug for such a harness..

 

[Robinson]

I meant driver side kick panel..

 

[AeroCoupe]

As far as I know from 91 thru 93 Ford stopped putting this harness in the 5.0 AOD cars and all the 4 cylinder cars but the 5.0 T5 cars will have it.

 

[Robinson]

Ok so where do I plug in when and if I get it or are you saying I don’t need it the t5 manual harness in this transfer

 

[AeroCoupe]

So for your 93 you need a 92.5-93 ECU harness, 87-93 manual trans O2 harness or repin an AOD harness (believe all those years will work but double check), 87-93 injector harness, and the NGS harness. You can make the headlight harness work with the V8 alternator location or just get the V8 harness.

I pulled everything from a 93 manual car (with the exception of the NGS harness) so it was plug and play when air swapped mine 21 years ago. They were a bit more plentiful then.

 

[Robinson]

I have the 1993 5.0 convertible donor so if I have to I will use the alternator headlight harness if need be..

Now I have the opportunity to purchase a A3m ecu and a 1993 harness manual although both items from different car price $400 ..for both

 

[Robinson]

I have the 1993 5.0 convertible donor so if I have to I will use the alternator headlight harness if need be..

Now I have the opportunity to purchase a A3m ecu and a 1993 harness manual although both items from different car price $400 ..for both