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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



Expert

Posts: 3689
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Location: Lower Mainland BC
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
----------------
Attachments 56DodgeNeutralSafetySwitchAndShiftLinkage.jpg (202KB - 19 downloads)
Attachments 56DodgeNeutralSafetySwitchTransmissionCombShowingDetentLever.jpg (195KB - 13 downloads)
Attachments 1704283_MechanicalNeutralSafetySwitch.jpg (196KB - 16 downloads)
Attachments 1704283_MechanicalNeutralSafetySwitch_2.jpg (149KB - 14 downloads)
Attachments 56DodgeNeutralSafetySwitch_NOSSwitchInstalled.jpg (220KB - 16 downloads)
Attachments PhilCourantsValveBodyPhoto.jpg (68KB - 20 downloads)
Attachments PhilCourantsSafetyLeverContactingSafetySwitchInNeutral.jpg (66KB - 13 downloads)
Attachments 58ChryslerStarterGeneratorIgnitionAndHornsWiringDiagram.jpg (162KB - 15 downloads)
Attachments PhilCourantsSafetyStartingCircuitDiagram.jpg (15KB - 14 downloads)
Attachments NeutralStarterSwitchPNs1704283And1770093.jpg (235KB - 14 downloads)
Attachments 1770093_VacuumNeutralSafetySwitch_3.jpg (104KB - 13 downloads)
Attachments 57Chizlers392PhotoShowingLocationOfTheNeutralSafetySwitch.jpg (200KB - 12 downloads)
Attachments 1960_DessPhotoOf392WithVacuumSafetySwitch.jpg (70KB - 12 downloads)
Attachments PowerFlites392VacuumFittingWithVacuumSafetySwitch.jpg (128KB - 12 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



Elite Veteran

Posts: 831
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Location: Pau, S-W France

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


Expert

Posts: 3042
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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



Expert

Posts: 3689
20001000500100252525
Location: Lower Mainland BC
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



Elite Veteran

Posts: 831
50010010010025
Location: Pau, S-W France
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



Expert

Posts: 3689
20001000500100252525
Location: Lower Mainland BC
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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Posts: 3689
20001000500100252525
Location: Lower Mainland BC
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



Expert

Posts: 3689
20001000500100252525
Location: Lower Mainland BC
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)



Attachments
----------------
Attachments RemoteStarterSwitchConnectionsOnA1956DodgeStarterSolenoid_Annotated.jpg (247KB - 4 downloads)
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