Painless EFI Harness without NSS??

All,

I have what appears to be an older versions of the Painless Performance EFI Harness as it has same wire color coding, same labeling, etc. as their current 60510 Harness except mine does not include a NSS wire from pin 30 on the ecm. Did previous versions bypass the NSS and essentially trick the computer into thinking it was in gear at all times? Also, if I wanted to add an NSS (or a Clutch Safety Switch in my case as I have an NP435) could I just add an old school mechanical switch to the clutch pedal in between the ignition switch and “S” terminal on the starter solenoid just as a preventative so I don’t take it thru the garage door by accident? Thanks in advance.

Hook up a switch just like your brake pedal has for turning on the stop lights.

Sorry, can't help ya with the NSS wiring...

With a MT just run pin 30 straight to ground.

The NSS does not run through the EFI harness. It's part of the chassis harness only, since it is the interconnect between the ignition switch and starter relay. Neither of which is connected to the engine computer.
The exception might be an Explorer DIS engine with 4R70 transmission.
Otherwise, you're good to go with whatever you connect yourself.

Are you replacing the chassis harness as well? Or just the engine harness?

Paul

In other words, if you connected it through the computer the engine might not start, but the starter would still crank.

Paul

Thanks for all the replies. The reason for my confusion is that the current installation instructions for the 60510 harness includes this wire in their harness and also lists the different instructions for connecting it depending on the computer/transmission combo on pages 19-22. However, my harness does not have anything connected to pin 30 so I'm assuming it was bypassed (grounded??) so that it always thinks it is in gear. The harness worked just fine when previously installed except for the fact that it could be started in gear. I am replacing the chassis harness and wanted to make sure that I had my starter circuit wired up correctly so I didn’t fry my computer.

Here’s a link to the 60510 harness instructions:
http://www.painlessperformance.com/Manuals/60510.pdf?

I am planning to reuse the the existing Painless EFI harness as it worked just fine and replace the chassis harness with the American Autowire Classic Update harness. Based on the replies above, I can add a mechanical switch to the clutch pedal to interrupt the starter circuit when the clutch is depressed. This switch would be placed in series before the “S” terminal on the starter solenoid and leave the EFI harness as is, correct? Thanks in advance.

Make sure to add a manual override switch to your safety switch.
Can be used either in case of a switch failure, OR (and this is the reason that Toyota did it on their 4wd trucks) in case you want/need to start the vehicle in gear to get rolling.
It's an old trick for getting rolling gently and controllably in a highly technical situation.

Paul

Ok, so I learned something new today. Although I now remember having seen NSS wires connected to the computer, really never thought about them. I did not think they were for interrupting the start process. Not sure how the computer is involved in the "S" wire for a starter relay, but there it is in (somewhat) black & white. Never had to use one though.
However what we've mentioned previously is still true, that your chassis harness will normally include everything you need for the NSS to function as a block for the starter motor, and will not need to be plumbed into the ECM as far as I know.

Maybe one of the ECM-experts will describe just what the EEC-IV setup has to do with the starter relay. Maybe it's an additional safety thing, or maybe it's so the computer knows what's going on for shift indicator lamps, or fuel pump function, or whatever. Doesn't seem likely it's for the START signal, since that would just say "start" I would think?
Not sure myself, so would love to know.

I've never had to connect any NSS or clutch-safety interlock switch to an engine harness before. But it's obviously there for a good reason.
Who's got the down and dirty?

Thanks

Paul

Paul,

Thanks for all your replies. The manual override switch is a great idea and something I will definitely incorporate into my rewire project.

I am by no means an EEC-IV expert but from my research pin 30 basically indicates to the ECM if the transmission is in park/neutral or in gear. From my understanding it acts as safety mechanism to during cranking but is also used by the ECM to adjust the idle settings between park/neutral vs in gear. It either sees power or ground and uses that to indicate if you’re in park/neutral or a drive gear. I’m assuming that my EFI harness was wired without anything connected to pin 30 and basically tricks the ECM into thinking it is always in gear. I’m also assuming this was done so that the harness could be installed with with any ECM (A9P, A9L, etc) and trans combo since these harnesses are typically used for retrofit applications. Hopefully one of the EFI experts can confirm if these assumptions are correct.

Well it that's the case it makes total sense. It in no way has anything to do with keeping the engine from cranking or starting. Just lets the computer know what the status of the transmission is.
Which would be why most modern transmissions have WAYYYY more wires coming out of their NSS' or "range switches" than our old simple old 4-wire switches had.

Paul

Forgive my lazy copy/paste job, I added a little to it:

There is no reason I can think of to run 12+ to pin 30 while cranking. I think the only reason it was done that way is so that the ground signal goes away during crank. It doesn't tell the PCM to enter crank mode. Crank mode is determined by RPM. The PCM is in crank mode until 300 rpm is exceeded, then it will not re-enter crank mode unless the rpms drop below 50.

It is rumored that the Auto computers had a diode in them to protect them from the 12v crank signal, and the manuals do not. It's also rumored that it usually won't hurt a manual PCM unless you get in to an extended crank situation, then it will eventually fry. I don't know how true that is because there is a much simpler solution......don't send power to pin 30 (and especially not to 46).

Where things really go south is with the mis-match O2 wiring harness and potentially sending 12 volts to SIG RTN (pin 46) during crank. That is guaranteed to smoke the trace in the PCM. My solution is to remove the o2 harness altogether. And once again...Don't send power to the PCM during crank.

The PCM only knows of 2 different states when it comes to pin 30. If pin 30 is grounded (same as run to SIG RTN) then the PCM thinks you are in neutral. If there is no ground signal on pin 30 then the PCM thinks you are in drive.

The idle speed, dashpot, and DFSO (decel fuel shut off) are handled differently between neutral and drive. You may like the way it idles or handles dashpot differently in neutral vs drive, or vice versa. You may also find it stalls when coming to a stop in drive, but doesn't in neutral. The extra idle hang (dashpot) in neutral might drive you nuts but find it more acceptable in drive.

Because of this, when I build a harness I install a jumper (re-used spout connector). One side is connected to pin 30. The other side is connected to ground (but sig rtn would work also). With the jumper in you get neutral, pull it you get drive. If you like the drive settings better but need to pull codes, simply toss the jumper back in to keep 67 from setting and allow the KOER test. This is why I say, if in doubt run pin 30 to ground (and nothing else). Now, if I'm also tuning the vehicle I build the harness for then I just ground pin 30 to keep from tossing 67 and tailor dashpot and the other idle settings to perfection. That is unless the vehicle is an automatic with an unused NSS, or an aftermarket shifter that has a switch for park and neutral. In that case I'll wire it so pin 30 is grounded in park or neutral and tune the idle air settings for both.

In short there is no reason to provide crank signal to any pin on the PCM. Doing so only adds to confusion and potentially smoked computers. You do still need to provide crank signal to the TFI module. The TFI module will lock timing during crank when the signal is present. That prevents hard starts when hot.
If you want to make sure your harness is safe and won't burn up a computer, then there is a simple test you can do. Remove the connector from the PCM and the wire from the S terminal of the starter solenoid (so it will not crank). Then test both pin 30 and pin 46 of the PCM connector for power while operating the ignition switch. Neither pin should show power in any key position including start. If either one has power you can potentially smoke the PCM.

EFI Guy,

Thank you for the detailed response and excellent explanation! So by leaving pin 30 blank (and therefore no ground path) my ECM thinks I’m in drive at all times, correct? If this is correct, could I just leave pin 30 blank in order to get “drive” characteristics and adjust the “neutral” settings via the idle set screw to help mitigate any stalling issues at idle? Thanks again for your reply.

Yes, if pin 30 is blank your PCM thinks you're in drive. You will need a way to ground it if you ever want to do a KOER test though.

Do not touch the screw! It's not an idle screw, it's a stop screw.

EFI Guy,

Thanks for confirming and also thanks again for the excellent explanation in your previous post! I’ve been tinkering on engines for along time but this is my first venture into the realm of EFI so I greatly appreciate detailed responses that not only answer the question at hand but provide the reasoning for it as well. In regards to providing a ground path for a KOER test, would a simple toggle switch between pin 30 and ground suffice since I don’t have an extra spout connector? If so, how what amp rating would you recommend?

Yes, there is no load on that circuit so it's going to be less than an amp. Which means just about any switch would work. You could even get fancy and use a double pole switch to also trigger the STI input. Then one switch would trigger neutral and put it into self-test mode. Just hit the switch and count the flashes.