t56 swap guys need help with neutral switch

[Joey7508]

I am in the middle of swapping my 3550 over to a viper spec t56. The connectors are now on the opposite side of the trans so I extended the wires and hooked up the vss and the back up lights. But on the rear of the 3550 right behing the shifter is the neutral saftey switch? Or at least thats what I think it is. Correct me if I am wrong. There isn't a place on the t56 for it that I see. So my question is do I bypass it? Any problem with bypassing it beside running the risk of starting it in gear or while its already running?
Also on there it a reverse lock out that has to be wired, ddperfomance sugggested may be to the brake switch . Its just to keep you from shoving it in reverse while running through the gears. Any of you guys wire it off the brake switch or did you do something different?

 

[jrichker]

The NSS or Neutral Safety SWitch does not have anything to do with starting the car in gear. It is used to prevent you from doing the Key On Engine Running computer diagnostic tests.

If it does not work, you will get a 67 code.

Code 67 - clutch not depressed (5 speed) or car not in neutral or park (auto) or A/C in On position when codes where dumped. Possible neutral safety switch or wiring problem. This code may prevent you from running the Key On Engine On tests. You can generally ignore this code, since it has no effect on engine performance.

The computer wants to make sure the A/C is off due to the added load on the engine for the engine running tests. It also checks to see that the transmission is in Neutral and the clutch depressed (T5, T56, Tremec 3550 & TKO)). This prevents the car from being driven while the computer is in test mode. Key On Engine Running test mode takes the throttle control away from the driver for several tests. This could prove hazardous if the computer was jumpered into test mode and then driven.

 

[FastDriver]

I'm posting 17 years later to update this since this post misled me when I searched for info on the NSS when converting to an '03 Cobra T56 from the T5. The T56 does not have a provision for the NSS. Jrichker was a saint in the Mustang community, and this isn't any knock on him, because so much of his content has been incredibly helpful to me. In this case, though, I need to set the record straight, in the hopes that this is helpful to anyone who stumbles through this like I have. The car's been running fine, but I have found that the NSS can definitely be relevant with regard to engine performance. Specifically, within the A9L's strategy, Idle timing can be set differently with regard to whether the transmission is in neutral or in 'drive', which the computer determines from the NSS. I'm not sure, as I've made a lot of changes since I started tuning, but I believe both of these tables are set up the same with the factory's strategy.

But Chris... if they're the same, why are you posting this correction?

Now, I haven't worked through whatever my specific problem is, yet, and if I do figure it out for certain, I'll come back to update this post, but... My car is not varying the ignition timing at idle. It's specifically locked to the 0-RPM-error commanded value of 20 degrees. My current theory is that because the A9L depends on the NSS to decide which table to use, my lack of an NSS signal is causing the A9L to command 20* without accounting for the RPM error in those tables, at all.

The point is, at the very least, Ford's EEC strategies do take the signal from the NSS into account. Even if the A9L doesn't vary timing, other strategies might. So, it would be best to keep the NSS, if possible. If I can validate this as my problem, I my look to provide a work-around such as always sending one signal or the other so that I can gain back control of idle ignition adjustments vs. RPM-error.

Here're the two tables I'm referring to & what Binary Editor's help file says about them:

"FN841D - ISC Spark Multiplier versus RPM Error in Drive (in gear - manual with neutral switch)."
"FN841N - ISC Spark Multiplier versus RPM Error in Neutral."

 

[FastDriver]

So, to follow up, I have made some progress... hopefully found a solution with the help of the eectuning.org guys. "TRLOAD" in binary editor's A9L Bin is a setting that tells the computer whether the clutch & 'gear' switches are working. I turned them off (=0), which tells the computer not to expect their signal and it forces the computer to perceive Neutral. This restored the computer's idle timing adjustments. Since they didn't mention any 2nd order tuning impacts while driving, I hope/suspect that only affects idle programming, but that remains to be validated. It's worth noting that setting it to 2, which tells it 1 of the switches is working, also restored idle timing. Since the NSS is tied into the clutch switch circuit, I'm not sure this has any functional difference. Here's what Binary Editor's help window says about it:

Given that telling the computer to ignore the NSS restored my idle timing, it looks like disabling the NSS absolutely impacts engine performance, at least at idle. That said, I was able to achieve a stable idle with static idle timing. Before the quarterhorse, I did so by turning up the idle RPM to maybe 900 or so with the throttle set screw & TPS reset. The exhaust would water your eyes. After the quarterhorse, it was a much more involved process, but I was able to reduce idle to 800 RPM, and improve the emissions some. I believe I *could* set RPM down another 100 or more, but the way the T56 rattles & engine shakes, 800 is probably where I'll leave it.

ps. I've switched to '2'. Maybe there's no functional difference, but I just didn't like the 'forced neutral state' verbiage. I want the computer to allow itself into the 'drive' tables if it can. It's unclear whether it can based upon the clutch switch alone, but for now, the car clearly idles with timing adjustments, and it also definitely calls for RPM appropriately when I'm coasting down to a stop. In other words, it seems to be using the speed sensor and/or other inputs to determine that it should not be idling until it's appropriate to do so.

 

[Dan02gt]

I fought with this years ago on my car. My understanding was that it's for the anti stall features. The clutch switch and trans switch are wired in parallel with each other and normally open. They close completing the circuit when either the trans is in neutral or the clutch is pressed in otherwise the ECU thinks the car is in gear and moving so it varies the timing to ensure it doesn't stall.

Someone had installed the wrong trans switch in my car that was closed with the trans in gear and opened when the car was in neutral. So with the clutch out and the trans in neutral the computer through the car was in gear an moving so the idle would shoot up to over 2k rpms.

I'm not sure that TRLOAD 2 or 3 matter on our cars since the switches are in parallel and the computer has no way of knowing which one is activated or if they are both activated.

 

[FastDriver]

Thanks. That must've made you want to pull your hair out. Without watching what the computer is doing very closely, I wouldn't think diagnosis would be possible. So far, I infer that 2 is effectively the same as 0, based on the way it's running/acting.