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Neutral Safety Switch - A compilation of info
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56D500boy
Posted 2018-09-21 7:54 PM (#570543)
Subject: Neutral Safety Switch - A compilation of info



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I normally drive standard transmission cars (e.g. 93 Audi Turbo S4, 94 Audi V8 S4) but I have owned and/or driven automatic transmission cars including a 65 Plymouth Fury III (my father's) and a 68 Plymouth Fury I (mine) and an 85 Plymouth Caravelle (think Dodge Diplomat) cop car (mine) over my 52 years of driving. That said, I never really realized what was going on with only being able to start the cars in Park or Neutral until I bought my 56 Dodge Custom Royal D500 with 2spd Powerflite two years ago. When the initial attempts were made at getting the engine started, the starter would not turn the engine over when "asked". It was deemed that the starter relay had failed. When a new four terminal starter relay was installed and the starter still didn't get power, it was realized that the neutral safety switch on the side of the Powerflite had failed. The short term solution (which lasted 2 years BTW) was to create a jumper wire from the ground terminal of the starter solenoid to a ground (in this case, under the bolt that held the solenoid to the fender).

The upside of this hack was I was finally able to get the starter to crank the engine over and, eventually, get the engine started. As such, I was happy enough to ignore the failed neutral safety switch while a) I found a new 1704 283 switch and b) I carried on with more important projects. The downside of the hack was I could now attempt to start the engine in any gear (D, L or R) not just neutral. Typically, I never made the mistake of doing that but recently I did inadvertently try to start the car, not realizing that the transmission was in Drive. Oops!! Fortunately, the eBrake was on and nothing really happened.

However, I did decide that I better finally install the 1704 283 Neutral Safety Switch (NSS) that I got from my local NOS guy, Ron W. I did that last week, while playing with my drive shaft U-joints and while I had the car jacked up so I could easily access the NSS. Once it was installed and the wiring at the solenoid hooked up properly, low and behold, I could NOT start the engine in D, L or R!! Just N like the Dodge (Chrysler) engineers intended. Yay.

During this process, I discovered that the later models, e.g. 57 and 58 and ??? had a second neutral starting safety switch that further protected the owner and the engine and/or starter. In this case, the second switch was on the intake manifold and was vacuum-activated. The intent was, with the engine in neutral and the starter circuit completed, the starter could NOT be engaged *IF* there was engine vacuum, i.e. the engine was already running. This would eliminate those nasty grinding noises and help facilitate the creation of the Neutral Starting Button (when the N button was depressed fully, the starter would be energized - but only if the engine wasn't running (and the key was in the RUN position)). (Note: This could be easily retrofit to a car like mine that didn't come with the neutral vacuum switch).

Based on all that I decided to compile information that I had gathered over the past two years from searches and from this forum. Here is what I found:

First of all, the wiring diagrams for a 56 Dodge (typical of that year) showing how the neutral safety switch created the ground for the solenoid signal from the ignition switch when turned to START.





Previously, I had posted:

56D500boy - 2016-12-15 7:20 PM

Patient = 56 Dodge V8 with Powerflite. During the initial attempt at starting it back in mid-September after not being started from 10 to 24 years ("barn" find car), it was determined that the neutral safety switch was not working. The short term solution was to permanently ground the wire that went to the switch. While this solved the problem in the short term, it is dangerous to continue on. To this end, I have purchased a new 1703 283 neutral safety switch. I understand that a rod or something pushes the plunger on the tip of the switch. However, while testing the NOS switch, I can NOT determine whether the switch is functioning properly, i.e. creating an electrical flow path from the terminal on the other end of the switch, through the switch to ground. It almost seems like the plunger part of the flow path, not just a means of interrupting the electrical flow.

How is this switch supposed to work? Where how do I test it with a multimeter (so I can test the old one to determine whether the issue is the switch or the rod that actuates the plunger).




To which 57Chizler responded:

57chizler - 2016-12-16 6:28 PM

The NSS provides a path to ground through the internal shift lever (rooster comb); in the pic below the switch/lever combo on the far left is the pre-'64. With a meter hooked to the threaded stud there should be continuity through the switch to the spring-loaded plunger on the opposite end of the switch whether or not the plunger is depressed.

It's actually pretty rare to find one that doesn't work, the usual reason for replacement is fluid leakage where the metal housing crimps onto the threaded stud insulator.


Here is 57Chizler's photo of the "rooster combs" in the transmission that shows the lever that contacts the NSS and allows the NSS to complete the circuit to ground.



The photos below show the 1704 283 for the side of the Powerflite (and early Torqueflite (??)) transmissions

Those are followed by the 57 and 58 and ?? cars with the additional 1770 093 vacuum-based neutral starting switch, the circuitry and the switch.

Thanks to 57Chizler, 1960_Des and Powerflite for use of their photos (previously uploaded to the forum) *PLUS* additional info and photos from Phil Courant in France (Merci Phil)


Edited by 56D500boy 2018-09-22 9:52 AM




(56DodgeNeutralSafetySwitchAndShiftLinkage.jpg)



(56DodgeNeutralSafetySwitchTransmissionCombShowingDetentLever.jpg)



(1704283_MechanicalNeutralSafetySwitch.jpg)



(1704283_MechanicalNeutralSafetySwitch_2.jpg)



(56DodgeNeutralSafetySwitch_NOSSwitchInstalled.jpg)



(PhilCourantsValveBodyPhoto.jpg)



(PhilCourantsSafetyLeverContactingSafetySwitchInNeutral.jpg)



(58ChryslerStarterGeneratorIgnitionAndHornsWiringDiagram.jpg)



(PhilCourantsSafetyStartingCircuitDiagram.jpg)



(NeutralStarterSwitchPNs1704283And1770093.jpg)



(1770093_VacuumNeutralSafetySwitch_3.jpg)



(57Chizlers392PhotoShowingLocationOfTheNeutralSafetySwitch.jpg)



(1960_DessPhotoOf392WithVacuumSafetySwitch.jpg)



(PowerFlites392VacuumFittingWithVacuumSafetySwitch.jpg)



Attachments
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Attachments 56DodgeNeutralSafetySwitchAndShiftLinkage.jpg (202KB - 438 downloads)
Attachments 56DodgeNeutralSafetySwitchTransmissionCombShowingDetentLever.jpg (195KB - 455 downloads)
Attachments 1704283_MechanicalNeutralSafetySwitch.jpg (196KB - 463 downloads)
Attachments 1704283_MechanicalNeutralSafetySwitch_2.jpg (149KB - 453 downloads)
Attachments 56DodgeNeutralSafetySwitch_NOSSwitchInstalled.jpg (220KB - 421 downloads)
Attachments PhilCourantsValveBodyPhoto.jpg (68KB - 432 downloads)
Attachments PhilCourantsSafetyLeverContactingSafetySwitchInNeutral.jpg (66KB - 423 downloads)
Attachments 58ChryslerStarterGeneratorIgnitionAndHornsWiringDiagram.jpg (162KB - 458 downloads)
Attachments PhilCourantsSafetyStartingCircuitDiagram.jpg (15KB - 448 downloads)
Attachments NeutralStarterSwitchPNs1704283And1770093.jpg (235KB - 422 downloads)
Attachments 1770093_VacuumNeutralSafetySwitch_3.jpg (104KB - 433 downloads)
Attachments 57Chizlers392PhotoShowingLocationOfTheNeutralSafetySwitch.jpg (200KB - 466 downloads)
Attachments 1960_DessPhotoOf392WithVacuumSafetySwitch.jpg (70KB - 410 downloads)
Attachments PowerFlites392VacuumFittingWithVacuumSafetySwitch.jpg (128KB - 444 downloads)
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Phil_the_frenchie
Posted 2018-09-22 7:12 AM (#570558 - in reply to #570543)
Subject: RE: Neutral Safety Switch - A compilation of info



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When i was "young" (!!!) i made a page about the neutral safety switch (57/58 cars), http://www.ch300imp.com/tqf-sw.htm#sw

 

wiring



Edited by Phil_the_frenchie 2018-09-22 7:14 AM
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mikes2nd
Posted 2018-09-22 9:12 AM (#570563 - in reply to #570543)
Subject: Re: Neutral Safety Switch - A compilation of info


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good stuff
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56D500boy
Posted 2018-09-22 10:00 AM (#570566 - in reply to #570558)
Subject: RE: Neutral Safety Switch - A compilation of info



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Phil_the_frenchie - 2018-09-22 7:12 AM

When i was "young" (!!!) i made a page about the neutral safety switch (57/58 cars), http://www.ch300imp.com/tqf-sw.htm#sw


Phil: Merci for the link. Good information there. I learned something about automatic transmissions as well as the neutral safety switch.:)

I have "stolen" your wiring diagram and two of your photos and incorporated them into my post above (credit to you in their upload names).

Merci beaucoup.

Edited by 56D500boy 2018-09-22 10:01 AM
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Phil_the_frenchie
Posted 2018-09-22 5:21 PM (#570582 - in reply to #570566)
Subject: RE: Neutral Safety Switch - A compilation of info



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No problem to use my diagrams or pics...
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56D500boy
Posted 2018-09-22 5:30 PM (#570583 - in reply to #570582)
Subject: RE: Neutral Safety Switch - A compilation of info



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Phil_the_frenchie - 2018-09-22 5:21 PM

No problem to use my diagrams or pics... :)


Merci. Much appreciated.

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56D500boy
Posted 2018-10-13 4:01 PM (#571627 - in reply to #570543)
Subject: RE: Neutral Safety Switch - A compilation of info



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In answer to a question about getting a car started without full wiring in place, I offered this explanation (which I am parking here for comments, as needed):

************

Normally, the 56 Dodge/Plymouth starter solenoids are not actually solenoids but more just a relay. With any relay, you want to use a low current trigger signal to pull a connection between the battery and a high current end point, e.g. the starter. This is much safer (few electrical fires) than trying to run the high current through the ignition switch.

So normally, with all the wiring in place, there is power to the ignition switch. When you turn the ignition switch to start, it directs a low current 12V signal to one of the small terminals on the starter solenoid (relay). With a standard transmission car, the body of the fender mounted solenoid grounds the solenoid so when you turn the ignition key to start, the current flows through the solenoid/relay to ground and the connection between the large cable from the battery and the large cable to the starter is made (inside the solenoid/relay) and with luck (good battery), the engine cranks on the starter. Assuming that the ignition switch is fully wired, there will also be 12V to the coil (or at least to the ballast resistor) and there will be spark and hey, maybe, an engine start.

With an automatic transmission, the safety guys said, hey look we need to prevent people trying to start their engine in gear (D or L or R) so we need to install a "Neutral Safety Switch" that will only flow through the low current 12V from the ignition switch in "START" when the transmission is in Neutral. That is a wise plan.

I am not clear on how much wiring you've got in place but the next thing that I am going to say assumes that you can deal with the power to the coil with the ignition switch in RUN. If you don't have that, all I am going to tell you is how to crank the engine on the starter by connecting some of the terminals on the four terminal solenoid.

The two larger terminals should be self evident, i.e. one should be the connection from the + terminal on the battery (12V neg ground in 1956), the other large terminal should be a thick cable going down to the starter.

The two smaller terminals are (1) the trigger power from the ignition switch (In START position) and (2) the connection to a working neutral safety switch. It should be a thinner wire that you can trace going down towards the transmission.

Assuming that you figured out which of the small wires is which and that the neutral safety switch is working and the transmission is in neutral, you should be able to get the starter to crank by temporarily connecting the large battery (+) terminal on the solenoid to the small ignition switch terminal on the solenoid. A complete hack can be done with a screw driver to bridge these two terminals. There will be sparks so safety could be an issue.

Otherwise, you can purchase a remote starter switch like one of these :



Should be able to find one for under $10 at PEPboys or O'Reillys or whatever.

Now, if you find that the engine is not cranked by the starter, then the neutral safety switch might not be working (my situation) or the wiring is compromised. A short term fix is to connect a wire between that second small terminal and a ground, e.g. the bolt that is holding the solenoid to the fender.

Assuming that you fix the solenoid ground issue, you should now be able to get the engine to crank on the starter with the transmission in neutral.

Once you are at that stage, and the rest of your wiring is in place, you can turn the ignition key to RUN and then use the remote starter to crank the engine and try to get it to start.

*IF* you don't have the ignition switch wired up, you could still theoretically get the engine started by running a separate small (16 gauge) wire from the + terminal on the battery to the input side of the ballast resistor and then immediately try to start the engine using the remote starter connected to the solenoid.

Hope that helps. "



Edited by 56D500boy 2018-10-13 9:03 PM
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56D500boy
Posted 2018-10-13 9:06 PM (#571641 - in reply to #571627)
Subject: RE: Neutral Safety Switch - A compilation of info



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Just to confirm that I knew what I was talking about (shocking I know ), I found my remote starter switch (hanging on a nail in the garage) and hooked it up as shown below. Initially, I just tried it without a key in the ignition. Worked (engine cranked). Then I put the key in the ignition and turned it to RUN (but not START). Then I went back to the engine bay and, with the transmission in neutral, I touched the remote starter switch and bingo, the engine started right off. Didn't even need to manipulate the throttle linkage. Gotta luv that Pertronix ignition





Edited by 56D500boy 2018-10-13 10:34 PM




(RemoteStarterSwitchConnectionsOnA1956DodgeStarterSolenoid_Annotated.jpg)



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Attachments RemoteStarterSwitchConnectionsOnA1956DodgeStarterSolenoid_Annotated.jpg (247KB - 414 downloads)
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56D500boy
Posted 2020-08-20 9:08 PM (#602347 - in reply to #570558)
Subject: RE: Neutral Safety Switch - A compilation of info



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I found a wiring diagram in the 1957 Dodge Factory Service Manual that flags the neutral safety switch, the vacuum switch and the neutral starter switch and how they all work together (only for 57-58 Dodge and Chryslers with Torqueflites):



Edited by 56D500boy 2020-08-20 9:11 PM




(57ChryslerDodgeNeutralStartingSwitch_WiringDiagram.jpg)



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Attachments 57ChryslerDodgeNeutralStartingSwitch_WiringDiagram.jpg (146KB - 333 downloads)
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mikes2nd
Posted 2020-10-03 2:30 PM (#603942 - in reply to #570543)
Subject: Re: Neutral Safety Switch - A compilation of info


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for my 57 dodge...

so when you are looking at the starter solenoid on the diagram you are looking at them "upside down"... the neutral safety switch goes to the S? and the start wire goes to the I?

I got a new one for the Dodge(from Rockauto) and typically I is used to go to the coil to bypass the resistor as it puts out 12 volts.... where S is the ignition start switch... hmm
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56D500boy
Posted 2020-10-03 4:27 PM (#603944 - in reply to #603942)
Subject: Re: Neutral Safety Switch - A compilation of info



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I can't help you with the "I" or the "S" per se but I can help with the logic.

The starter solenoid is just a big relay that uses a low current 12V input to close contacts between two high current devices, i.e. the battery and the starter.

As such, the low current trigger signal input and ground are connected to the two smaller of the four solenoid terminals and the battery and starter are connected to the two large terminals (with relatively thick cables, etc).

So in the case of a 1957 Dodge you turn the key to run and then push the "N" button on the Torqueflite shifter box. That completes part of the circuit that will eventually trigger the starter but to complete the rest, the engine has to be stopped. This closes the vacuum (another safety) switch allowing current to carry on two one of the smaller terminals on the solenoid. However, nothing happens unless that low current has somewhere to go, in this case to ground via the second small terminal, connected to the neutral safety switch on the transmission.

*IF* all those ducks line up, the current flow from the ignition switch to the neutral starting switch, through the vacuum switch on the engine and then to the small input terminal on starter solenoid and then out to ground via the neutral safety switch. Bingo, the big current contacts are closed and big current flow from the battery to the starter.

The 12V to the ignition is a whole separate thing (different terminal on the ignition switch (either "IGN" or maybe just "I") with a dark blue wire.



Edited by 56D500boy 2020-10-03 4:35 PM
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mikes2nd
Posted 2020-10-03 10:54 PM (#603952 - in reply to #570543)
Subject: Re: Neutral Safety Switch - A compilation of info


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figured it out. There are remote and starter based starter solenoids...

The "big engine" cars use the starter solenoids directly attached to the starter... the polys use remote starter solenoids...

The remote ones look JUST like the Ford ones.. If you see an I or S terminal it wont work... its almost like a mower "pole" starter solenoid.

It has ground, start ignition wire, batter, to starter... Ground is run by the neutral safety switch(vacuum if push button).

Since I bought a "aftermarket" starter... I am going with a high powered relay that I can use as a terminal and run the starter wire through.

If you leave the original starter solenoid you need to jumper the starter.





(711m+fSb4YL._AC_SL1500_.jpg)



(51NzGtqSrRL._AC_SL1000_.jpg)



Attachments
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Attachments 711m+fSb4YL._AC_SL1500_.jpg (101KB - 262 downloads)
Attachments 51NzGtqSrRL._AC_SL1000_.jpg (35KB - 264 downloads)
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mikes2nd
Posted 2020-10-04 12:51 AM (#603953 - in reply to #570543)
Subject: Re: Neutral Safety Switch - A compilation of info


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This is a good replacement for the OEM starter solenoid if you have this stle, not like the 150$ they want for oem from some jackwagon on ebay.

Just like it though. STANDARD MOTOR PRODUCTS SS567 12$ at rockauto.. guess i should do a vid or make a thread.

I think for the manual trans versions you can use anything you want, even the ford versions because you dont care about the neutral safety switch.

 



Edited by mikes2nd 2020-10-04 12:56 AM




(solenoid.jpg)



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Attachments solenoid.jpg (112KB - 267 downloads)
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56D500boy
Posted 2020-10-04 2:49 AM (#603954 - in reply to #603953)
Subject: Re: Neutral Safety Switch - A compilation of info



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1692 659 is a good PN for 56-58 Plymouth and Dodge and 57-58 Desoto S27 and LSI (Dodge-based FireSweeps) w/PowerFlite or Auto. 3 Speed (Torqueflite) Trans., so that Rock Auto four terminal solenoid should work.

I would agree about the manual trans solenoids. They only need a trigger signal terminal (they ground through their mounts) and the larger battery and starter terminals.



Edited by 56D500boy 2020-10-04 2:51 AM
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56D500boy
Posted 2022-01-18 7:40 PM (#618606 - in reply to #603954)
Subject: Location of the Neutral Safety Switch on the Cast Iron Torqueflites



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I thought that I should be more complete and add the locations of the Neutral Safety Switches on the first (56-58) and second (59-61) generation cast iron Torqueflites.

In both cases, I believe that you could swap these out for new ones by jacking up the driver's (left) side of the car to tilt the ATF away from the Neutral Safety Switch
hole and not have to drain fluid to do the job.



Edited by 56D500boy 2022-01-19 10:57 AM




(1957WindsorTorquefliteShowingLocationOfTheNeutralSafetySwitch.jpg)



(1959TorquefliteWithNeutralSafetySwitch_Annotated.jpg)



(1704283_MechanicalNeutralSafetySwitch.jpg)



Attachments
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Attachments 1957WindsorTorquefliteShowingLocationOfTheNeutralSafetySwitch.jpg (120KB - 47 downloads)
Attachments 1959TorquefliteWithNeutralSafetySwitch_Annotated.jpg (123KB - 48 downloads)
Attachments 1704283_MechanicalNeutralSafetySwitch.jpg (121KB - 49 downloads)
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