SR/KA Neutral switch - normally open? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

KoukiMonsta · 07-16-2018, 06:09 AM

Talkin' Sr or KA manual trans.

Is the neutral switch the same as the reverse/5th gear switch?

I was under the assumption the neutral switch went to ground when in neutral, so ECU would see ground at that terminal when in neutral. I just assumed this for whatever reason.

But my trusty multimeter tells me that ain't true. The switch is normally open, meaning open in neutral and closed in gear.

I can't trust that the switch I have in that spot is correct, it 'could' be a reverse switch for all I know...unless they are all the same?

onehundredoctane · 07-16-2018, 07:46 AM

That's backwards. . . the only way that it could work is if the neutral safety switch was closed when in neutral, to complete that circuit and allow 12v to go to the starter.

LoSt180 · 07-16-2018, 08:06 AM

The neutral switch has nothing to do with the starter interlock. That comes from a switch on the clutch pedal, or park/neutral sensor in an auto trans.

KoukiMonsta · 07-16-2018, 10:04 AM

I am NOT describing the switch on the clutch pedal.

It COULD work either way, it depends how the ECU functions - which is the whole point of my question. I do not know how it functions.

LoSt180 · 07-16-2018, 11:56 AM

The ECM detects the park/neutral position when continuity with ground exists.

When the gear position is in neutral, the PNP switch is "ON".

In electrical terms, the switch "closes" the circuit when in neutral, and "opens" the circuit in any other position.

Here's the circuit diagram for the neutral position switch. Drawing is the same for all S-chassis manuals I have on hand.

The KA 5th position and reverse switches function the same way.

KoukiMonsta · 07-16-2018, 02:06 PM

Quote:

Originally Posted by LoSt180

The ECM detects the park/neutral position when continuity with ground exists.

In electrical terms, the switch "closes" the circuit when in neutral, and "opens" the circuit in any other position.

The thing is, using a multimeter and probing the leads, this is not true.

In neutral I have zero, open, continuity. In gear I have continuity.

I think I am going to remove the switch, PITA to get to tho..and confirm my sanity as to whether is is NO or NC.

It's bee a long time since I had a tranny open, but I am not visioning how this would work - unless the switch is normally closed. I don't see any way the switch could be depressed in any shifter position other than neutral.

onehundredoctane · 07-17-2018, 07:42 AM

I know it's not "advised". . . but you can bypass it so the car will start regardless.

Several cars I've owned were this way since they were originally autos.

KoukiMonsta · 07-18-2018, 05:33 AM

Quote:

Originally Posted by onehundredoctane

I know it's not "advised". . . but you can bypass it so the car will start regardless.

Several cars I've owned were this way since they were originally autos.

this switch, located on the rear end of the transmission, has nothing at all to do with that.

This is strictly input the the ECU.

I am wiring the car from scratch, and it sure as shit doesn't have the clutch interlock switch.

07-16-2018, 06:09 AM	#1
KoukiMonsta Nissanaholic! Join Date: Mar 2009 Location: NC Posts: 1,969 Trader Rating: (23) Feedback Score: 23 reviews	SR/KA Neutral switch - normally open? Talkin' Sr or KA manual trans. Is the neutral switch the same as the reverse/5th gear switch? I was under the assumption the neutral switch went to ground when in neutral, so ECU would see ground at that terminal when in neutral. I just assumed this for whatever reason. But my trusty multimeter tells me that ain't true. The switch is normally open, meaning open in neutral and closed in gear. I can't trust that the switch I have in that spot is correct, it 'could' be a reverse switch for all I know...unless they are all the same? __________________ @UpshiftEngineering

07-16-2018, 08:06 AM	#3
LoSt180 Zilvia Addict Join Date: May 2013 Location: MD Posts: 966 Trader Rating: (18) Feedback Score: 18 reviews	The neutral switch has nothing to do with the starter interlock. That comes from a switch on the clutch pedal, or park/neutral sensor in an auto trans. Last edited by LoSt180; 07-18-2018 at 06:04 AM..

07-16-2018, 10:04 AM	#4
KoukiMonsta Nissanaholic! Join Date: Mar 2009 Location: NC Posts: 1,969 Trader Rating: (23) Feedback Score: 23 reviews	I am NOT describing the switch on the clutch pedal. It COULD work either way, it depends how the ECU functions - which is the whole point of my question. I do not know how it functions. __________________ @UpshiftEngineering

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07-16-2018, 07:46 AM	#2
onehundredoctane Post Whore! Join Date: Oct 2006 Location: Greensborough, NC Posts: 2,783 Trader Rating: (3) Feedback Score: 3 reviews	That's backwards. . . the only way that it could work is if the neutral safety switch was closed when in neutral, to complete that circuit and allow 12v to go to the starter.

07-16-2018, 11:56 AM	#5
LoSt180 Zilvia Addict Join Date: May 2013 Location: MD Posts: 966 Trader Rating: (18) Feedback Score: 18 reviews	The ECM detects the park/neutral position when continuity with ground exists. When the gear position is in neutral, the PNP switch is "ON". In electrical terms, the switch "closes" the circuit when in neutral, and "opens" the circuit in any other position. Here's the circuit diagram for the neutral position switch. Drawing is the same for all S-chassis manuals I have on hand. The KA 5th position and reverse switches function the same way.

07-17-2018, 07:42 AM	#7
onehundredoctane Post Whore! Join Date: Oct 2006 Location: Greensborough, NC Posts: 2,783 Trader Rating: (3) Feedback Score: 3 reviews	I know it's not "advised". . . but you can bypass it so the car will start regardless. Several cars I've owned were this way since they were originally autos.