Magnum Neutral Safety Switch, effect idle? and wiring?

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robcuda

robcuda

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Hi guys. 97 stock efi obdII swap. Getting a code for NSS. A 3 pin connector.
First of all, if the NSS is not operating will it effect the idle?
While trying to fix, I am curious what triggers the code, the center pin only?
Pic below of pin-out.

-Can I focus only on the center pin to get the NSS to work? I don't care about the reverse lights (outer pins) right now. OR, do the outer pins ground the center?

-I have located the center wire: Brown/Orange
-Also located the third wire: Violet/Black
-It calls for a white wire for the 1st pin but I can not locate it. There is a Black/green wire (the only unaccounted for wire in the trans harness that is right at the bundle of other NSS wires but I am skeptical in hooking it up to NSS (it is a Black/Green, slightly larger gauge wire and I doubt manual is wrong about color but is it possible?)
Thanks for any ideas!

NSS.jpeg
 
I don't know why it would affect the vehicle running once you get it started. Could be the switch, connections, harness, something in the trans/ linkage, I don't know whether it's integrated into the controller.
 
67Dart273 said:
I don't know why it would affect the vehicle running once you get it started. Could be the switch, connections, harness, something in the trans/ linkage, I don't know whether it's integrated into the controller.
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Just found this from Dodge "NSS is used to determine idle speed (varying with gear selection), fuel injector pulse width, ignition timing advance and vehicle speed control operation."
 
robcuda said:
Just found this from Dodge "NSS is used to determine idle speed (varying with gear selection), fuel injector pulse width, ignition timing advance and vehicle speed control operation."
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I’ve found this to be true. On a stock ecu program, they bump the timing and raise the idle slightly when it comes out of neutral and goes in to gear. It keeps the idle speed consistent when the engine goes from unloaded (park/neutral) to loaded (in gear with your foot on the brake). Most factory efi systems do the same.
 
Same reasoning behind having a sense line on the ac compressor clutch.
 
TT5.9mag said:
I’ve found this to be true. On a stock ecu program, they bump the timing and raise the idle slightly when it comes out of neutral and goes in to gear. It keeps the idle speed consistent when the engine goes from unloaded (park/neutral) to loaded (in gear with your foot on the brake). Most factory efi systems do the same.
Click to expand...
Thanks for the input. Any tips on wiring just the center pin? Or do all 3 pins have to be wired for full functionality?
 
I would say pin 2 definitely needs to be wired for functionality of the ecu. Pin 1 and 3 are wired for reverse light activation. At least I think. Test it with a multimeter. In reverse if you have continuity between 1-3 and it goes away in any other gear then the power is used to light the reverse lights. I’m betting pin 2 will have continuity to ground in park and neutral but open in any other gear. I don’t have a 3 pin switch here to test or I’d do it.
 
As TT5.9mag said, the center pin should be grounded in park and neutral by the switch. This provides ground for the starter relay but the PCM also monitors that wire so it knows the status. The code is likely setting because the PCM sees startup and drive cycles without ever seeing that wire changing status.
If I am seeing this correctly, the wire should come from pin 2 of the park neutral switch, splice off at S127 and to both terminal 85 of starter relay in the PDC and to pin 6 in connector 1 of the PCM.

Note that I am using a 1999 wiring diagram, so it could be different than your 1997, but so far everything I have compared for engine and transmission has always lined up the same.

If you had a manual transmission PCM, or reprogram your PCM as a manual transmission, it will ignore this circuit and code.
 
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Bobzilla said:
As TT5.9mag said, the center pin should be grounded in park and neutral by the switch. This provides ground for the starter relay but the PCM also monitors that wire so it knows the status. The code is likely setting because the PCM sees startup and drive cycles without ever seeing that wire changing status.
If I am seeing this correctly, the wire should come from pin 2 of the park neutral switch, splice off at S127 and to both terminal 85 of starter relay in the PDC and to pin 6 in connector 1 of the PCM.

Note that I am using a 1999 wiring diagram, so it could be different than your 1997, but so far everything I have compared for engine and transmission has always lined up the same.

If you had a manual transmission PCM, or reprogram your PCM as a manual transmission, it will ignore this circuit and code.
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Bobzilla, thanks so much for this info. I am new at reading schematics so I'm a little slow. This will help me track this down. With a splice such as S127 is it a matter of following the wire to the splice? I'm assuming the splice could be anywhere along the harness, correct? Also, do you think the center pin is grounded through the harness, pdc, or pcm independent of the outside pins? Thanks a bunch!
 
robcuda said:
Bobzilla, thanks so much for this info. I am new at reading schematics so I'm a little slow. This will help me track this down. With a splice such as S127 is it a matter of following the wire to the splice? I'm assuming the splice could be anywhere along the harness, correct? Also, do you think the center pin is grounded through the harness, pdc, or pcm independent of the outside pins? Thanks a bunch!
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The center pin is grounded by the switch itself. The wire to the ecu is a “sense” wire.
 
S127 can be thought of as a simple “T” where one wire becomes two. One leg goes to the ecu and one goes to the starter relay.
 
TT5.9mag said:
S127 can be thought of as a simple “T” where one wire becomes two. One leg goes to the ecu and one goes to the starter relay.
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You guys are awesome, I feel like I'm getting this close to running properly, very excited!
 
I just looked back to find the donor vehicle from your other thread. Looks like it was a B3500 van with 5.9 Magnum. That means my post number 10 has the incorrect splice and PCM connector numbers, since I assumed the donor was a pick-up truck. If the diagram I am looking at now is correct, it will be pin 6 of connector 2 at PCM, and it goes through splice S119. The way it works and is wired is still the same.

Also, your questions from post 11 were already answered correctly by TT5.9mag, so I will just click the agree button for his posts. Lol.

Edited for spelling correction only.
 
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Bobzilla said:
I just looked back to find the donor vehicle from your other thread. Looks like it was a B3500 van with 5.9 Magnum. That means my post number 10 has the incorrect splice and PCM connector numbers, since I assumed the donor was a pick-up truck. If the diagram I am looking at now is correct, it will be pin 6 of connector 2 at PCM, and it goes through splice S119. The way is works and is wired is still the same.

Also, your questions from post 11 were already answered correctly by TT5.9mag, so I will just click the agree button for his posts. Lol.
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Thanks for posting the correction for my B3500 I appreciate it. I'm learning schematics for the first time and any tips on where to start is very helpful! Right now I have the center pin connected but still starts in Drive and Reverse. Will start testing the way you guys suggested and follow wires.
On another note, I just tracked my idle problem to a bad 02 sensor. Although it worked in the donor it must have gotten banged up during the swap and was not giving me a code. My first enjoyable test drive, LOL!
 
So you are actually having a an issue, not just a code setting, since you say it starts in drive and reverse.
When you did the wiring originally, how did you set up your starter? Is it using the Magnum harness and relay or is it using the car's original starter relay?
 
Bobzilla said:
So you are actually having a an issue, not just a code setting, since you say it starts in drive and reverse.
When you did the wiring originally, how did you set up your starter? Is it using the Magnum harness and relay or is it using the car's original starter relay?
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That's a great question. I had a guy help me get it fired up and I honestly don't know. But I see where you are going, if it's using the original relay it would not be communicating with the NSS, correct?
 
If it is using the magnum harness and starter relay then he (or you) must have added an external ground to pin 85 on that relay. That would bypass the NSS.
 
Bobzilla said:
I just looked back to find the donor vehicle from your other thread. Looks like it was a B3500 van with 5.9 Magnum. That means my post number 10 has the incorrect splice and PCM connector numbers, since I assumed the donor was a pick-up truck. If the diagram I am looking at now is correct, it will be pin 6 of connector 2 at PCM, and it goes through splice S119. The way it works and is wired is still the same.

Also, your questions from post 11 were already answered correctly by TT5.9mag, so I will just click the agree button for his posts. Lol.

Edited for spelling correction only.
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My B3500 has a 5 pin connector, and the same year pickup has 3, why did Dodge do that?
 
Ceedawg said:
My B3500 has a 5 pin connector, and the same year pickup has 3, why did Dodge do that?
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I assume you are seeing the difference between the RH hydraulically controlled transmissions with less wires and a newer RE electronically controlled transmission with more wires.
 
Bobzilla said:
I assume you are seeing the difference between the RH hydraulically controlled transmissions with less wires and a newer RE electronically controlled transmission with more wires.
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Both are electronic controlled, used my case and the new guts from the truck trans. Other than the NSS and the pressure sensor on the valve body, identical same year too. Bigger hole for the 5 pin too, reason I had to use my case. (Sorry for the hyjack)
 
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Ceedawg said:
Both are electronic controlled, used my case and the new guts from the truck trans. Other than the NSS and the pressure sensor on the valve body, identical same year too. Bigger hole for the 5 pin too, reason I had to use my case. (Sorry for the hyjack)
Click to expand...
Interesting. I am not familiar with this one.
 
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