Neutral Safety Switch help!!!

Discussion in 'First Generation Challenger Forum' started by Brandon Ross, Jan 14, 2020.

  1. Brandon Ross

    Brandon Ross Member

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    Trying to resolve NSS issues on my 1970 Dodge Challenger. I have a brand new NSS, three prong. I also purchased a new pigtail just to ensure good connection. The middle brown/yellow wire goes to connection "G" on the starter relay like its supposed to. The black and black/white follow their path correctly as well. If i short out the black and black/white at the plug connection, the reverse light comes on. I checked continuity across the two outside pins of the brand new NSS in all gears and its open in all gears. I would expect continuity in reverse as it is actuated to close the loop for reverse lights. Car will not start in any gear. If I add a cable from the "G" point on the starter relay to the negative terminal of the battery like the previous owner had, the car will start in any gear and there is still no reverse lights in any gear. I am out of ideas shy of assuming i got a bad NSS. Any help is greatly appreciated.
     
  2. 2010RT

    2010RT Full Access Member

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    Perhaps the previous owner had wired it wrong. You should look into getting the wiring schematic from a service manual to see how it was supposed to be wired. Starting the car in any gear throws up a flag for me.
    Maybe try Googling wiring diagrams for 70 Challenger. I am working on a 52 pickup and am amazed at what you can find on line.
     
  3. Brandon Ross

    Brandon Ross Member

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    Mark,

    I have all the wiring diagrams. The NSS and reverse lights are now wired up exactly per the correct wiring diagram as far as i can tell. To me it says something is not connecting at the NSS inside the transmission, but i'm no certified mechanic and my knowledge of transmissions is very slim.
     
  4. B5blueRT

    B5blueRT Full Access Member

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    I assume from what you wrote: BLK wire is GROUND; WHT/BLK wire goes to the backup lamps and the BROWN/YELLOW wire goes to the starter solenoid terminal G.
    1. You already proved the wiring going to the backup lamps is good (has continuity) by shorting out the WHT/BLK wire to the BLK wire.
    2. Try shorting the BLK wire to the BROWN/YELLOW wire. The starter should crank with the ignition switch, same as running a wire from the G terminal or the solenoid to the NEG on the battery.
    3. If it doesn't crank, you have a bad connection somewhere on that BROWN/YELLOW wire between the NSS and the starter solenoid. Have that wire unplugged at both ends and check continuity.
    4. If it does crank, there is either a problem with the NSS or whatever activates it inside the trans. I'm not familiar with this, I've only seen external switches where you can see the mechanism that's connected to the switch. Hopefully you can take the switch out to move the activator manually and check continuity with it unplugged. If you can move the mechanism, BLK shorted to BROWN/YELLOW terminals should show 0 ohms only in two positions, Park and Neutral, the BLK shorted to BLK/WHT terminal should be 0 ohms only in reverse.
    If those measure correctly, the switch is good.

    Hope I didn't confuse you.
     
  5. KEVIN DONOVAN

    KEVIN DONOVAN Full Access Member

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    You try turning the plug around on the NSS?
     
  6. Brandon Ross

    Brandon Ross Member

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    B5blueRT,

    The black/white wire goes to fuse block (fuse is good) and the black wire goes back to the lightbulb (also confirmed good). The brown/yellow wire goes to the starter relay.

    Kevin,

    Flipping the plug around would do nothing. The NSS is just a switch. Inside transmission should push the nub inside, closing the circuit between black/white and black wires.
     
  7. Brandon Ross

    Brandon Ross Member

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    B5blueRT,

    The black/white wire goes to fuse block (fuse is good) and the black wire goes back to the lightbulb (also confirmed good). The brown/yellow wire goes to the starter relay.

    Kevin,

    Flipping the plug around would do nothing. The NSS is just a switch. Inside transmission should push the nub inside, closing the circuit between black/white and black wires.
     
  8. Brandon Ross

    Brandon Ross Member

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    UPDATE: So i pulled the brand new NSS and bench tested it. It failed and is working the opposite of what it should. While this is frustrating, I found a bigger issue. Just checked the numbers on the side of the transmission (not sure why i didn't do this sooner) and the trans is a 66. This means it was made for a 1 stud NSS. The car is a 70, so the reverse lights are set up to operate off a 3 stud. So i have to figure out if i can swap the rooster comb in the valve body for a 1970 to accommodate the three stud NSS or i have to wire up a microswitch to actuate the reverse lights somehow.