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Thread: Safety Switch Question

  1. #1
    Mark Eaton's Avatar
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    Safety Switch Question

    I have forgotten what the plan is for the neutral safety switch on my TKO 600. I'm running a DART 347 with EFI. Pretty sure that having the clutch safety switch will make this obsolete and if I wire it through my starter wire will just make a redundancy? Or do people wire it in?



    Thanks,

    Mark
    MK4 #9130 , complete kit, arrived 8/10/2017, Street Legal 2/14/2020.
    DART SHP 347, EFI, TKO600, IRS
    http://thefactoryfiveforum.com/showt...n-Build-Thread

  2. #2
    Seasoned Citizen NAZ's Avatar
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    I grew up without safety switches so unless there is a rule requiring them on a manual, I don't use them. I'm sure the neutral safety and clutch safety switches came about because some Adam Henry sued a deep pocket corporation for his own stupidity. Even one of my tractors has a clutch safety switch.

    Automatic is a different story. Even I agree that a neutral safety switch is required.
    Dart Little M 406" SBC 800 HP N/A & 1,100 HP on nitrous, 2-spd Powerglide with trans brake, 6,000 RPM stall converter, narrowed Moser 88 3.90:1 spool with 35-spline gun-drilled axles & Torino bearings, custom parallel four-link, custom tube chassis & roll cage NHRA certified for 8.5-sec (only two FFR Hot Rods have this cert).

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  4. #3
    Papa's Avatar
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    I think the clutch safety switch is fine and you don't need to use the neutral safety switch.
    My Build Thread: http://thefactoryfiveforum.com/showt...ter-Build-9754
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    Senior Member CDXXVII's Avatar
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    My understanding is that the TKO neutral switch is not designed to carry a load. I have my clutch switch and TKO neutral switch wired in parallel to a relay. My relay handles the load and either switch activation allows me to start the engine.
    Last edited by CDXXVII; 03-10-2019 at 04:48 PM.
    F5R #7841: Anniversary Edition MK4, Ford Racing 427, Edelbrock EFI, Gas-N Pipes, Stainless Headers, TKO600, 3.31 Moser 3-Link, 17" Halibrands

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  8. #5
    Senior Member skidd's Avatar
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    Quote Originally Posted by CDXXVII View Post
    My understanding is that the TKO neutral switch is not designed to carry a load. I have my clutch switch and TKO neutral switch wire in parallel to a relay. My relay handles the load and either switch activation allows me to start the engine.
    +1. I did the same thing. Came in really handy being able to start the car in Neutral, without having to get into the car and press the clutch pedal.
    2016 MK4 | '99 Explorer 5.0 | E303&600cfm carb | T5z + 3.55 | 3-link | SN95 | PB/PS | FR500 17" 315&275 |

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  10. #6
    Well Used Member boat737's Avatar
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    Quote Originally Posted by skidd View Post
    +1. I did the same thing. Came in really handy being able to start the car in Neutral, without having to get into the car and press the clutch pedal.
    X3 for me. Starts in neutral, or in gear with the clutch pedal depressed.
    If Brute Force doesn't work, you're not using enough of it.
    Basic Stuff: MK4 Complete Kit #8439, Wilwood's, 17" Halibrands. Extra Stuff: Stainless brake and fuel lines, Breeze cooling, Battery mount, SS Roll Bar. Old Fart Stuff: Heater, Seat Heaters, Footbox Fresh Air, Stereo, Keyless ignition, Power Steering, Hyd Clutch.
    Young & Dumb Stuff: 427w Dart, TKO600, 3 link Moser M9/Ford 9", 3.5:1, Eaton TruTrac Posi. Graduation Thread

  11. #7
    Member Jim Doak's Avatar
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    X4.
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  12. #8
    Mark Eaton's Avatar
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    How exactly would you wire that relay?
    MK4 #9130 , complete kit, arrived 8/10/2017, Street Legal 2/14/2020.
    DART SHP 347, EFI, TKO600, IRS
    http://thefactoryfiveforum.com/showt...n-Build-Thread

  13. #9
    Senior Member skidd's Avatar
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    In my case.. the way I did it was to start with a standard 5 pin relay that is tasked with actually powering the starter solenoid.
    I happen to have a S2K push-start button in my car that triggers the relay (And a DEI 2102T for security).
    Triggering this relay, sends 12v to the starter solenoid. (pin 30 -> Pin 87) Could easily come from the "start" position on a standard ignition key.
    So, the start button feeds 12v to the coil terminal on the relay (pin 85).
    The ground side of the relay coil (pin 86) goes to both the neutral safety switch in my T5, and the clutch switch on the peldal box.
    This ground from the relay goes to both of these switches in parallel. Then, the other side of these switches is grounded directly to the frame.

    Pardon my crude attempt at ascii-based wiring diagrams
    Code:
    12v -> Ignition Key ------> On ------> Pin-30  ~  Pin-87 ------> Starter
                        \
                         \-----> Start -----> Pin-85  ~  Pin-86 -----> Trans Switch ----> Ground
                                                            \
                                                             \-----> Clutch Pedal Switch -----> Ground
    2016 MK4 | '99 Explorer 5.0 | E303&600cfm carb | T5z + 3.55 | 3-link | SN95 | PB/PS | FR500 17" 315&275 |

  14. #10
    Well Used Member boat737's Avatar
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    I did basically the same. I did add a bypass switch to eliminate the clutch and safety switches and the relay in case of a circuit/wiring failure. And since I had the NC pos (Pin 87A) available, I wired that through an adjustable rate flasher to my dash red-warning light (same red light as the low-voltage, and the parking-brake-set, used blocking diodes to separate the 3 systems). It flashes if the start circuit is activated with out being in neutral or the clutch pressed. The starter won't engage, but is telling why--it's in gear with the clutch not depressed. Overkill I know, but it works.
    Attached Images Attached Images
    Last edited by boat737; 03-12-2019 at 09:27 PM.
    If Brute Force doesn't work, you're not using enough of it.
    Basic Stuff: MK4 Complete Kit #8439, Wilwood's, 17" Halibrands. Extra Stuff: Stainless brake and fuel lines, Breeze cooling, Battery mount, SS Roll Bar. Old Fart Stuff: Heater, Seat Heaters, Footbox Fresh Air, Stereo, Keyless ignition, Power Steering, Hyd Clutch.
    Young & Dumb Stuff: 427w Dart, TKO600, 3 link Moser M9/Ford 9", 3.5:1, Eaton TruTrac Posi. Graduation Thread

  15. #11
    Boydster's Avatar
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    Quote Originally Posted by boat737 View Post
    I did basically the same. I did add a bypass switch to eliminate the clutch and safety switches and the relay in case of a circuit/wiring failure. And since I had the NC pos (Pin 87A) available, I wired that through an adjustable rate flasher to my dash red-warning light. It flashes if the start circuit is activated with out being in neutral or the clutch pressed. Overkill I know, but it works.
    Thats actually kinda cool. "Warning, Warning, engage clutch before starting." Like bad stuff can happen really quick.
    ---Boyd---
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  16. #12
    Senior Member rich grsc's Avatar
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    Quote Originally Posted by CDXXVII View Post
    My understanding is that the TKO neutral switch is not designed to carry a load. I have my clutch switch and TKO neutral switch wired in parallel to a relay. My relay handles the load and either switch activation allows me to start the engine.
    There is no load on the start wire, it just engages the starter relay. So you now have a relay operating a relay. Doesn't hurt anything, just not needed at all.

  17. #13
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    Quote Originally Posted by boat737 View Post
    I did basically the same. I did add a bypass switch to eliminate the clutch and safety switches and the relay in case of a circuit/wiring failure. And since I had the NC pos (Pin 87A) available, I wired that through an adjustable rate flasher to my dash red-warning light. It flashes if the start circuit is activated with out being in neutral or the clutch pressed. Overkill I know, but it works.
    Boat-

    Thanks for posting the details on this! The warning light idea is kind of cool too; I am going to have to think about that...

    I really appreciate the wiring diagram too! It doesn't look too hard to emulate. But, if there's a way to screw it up, I bet I kind find it.

    Skidd-

    Thanks for your details as well; especially the ascii diagram -- pretty cool!

    I also appreciate the other folks who chimed in confirming how they wired theirs. It helps to have confirmation, especially when you are weak in that part of the build.

    Thanks everyone. I sure do love having this resource!!

    Regards,

    Steve

  18. #14
    Senior Member skidd's Avatar
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    Quote Originally Posted by rich grsc View Post
    There is no load on the start wire, it just engages the starter relay. So you now have a relay operating a relay. Doesn't hurt anything, just not needed at all.
    A slight over simplification. There is a load, it's just not a relatively big load. Some starter solenoids pull less than an amp to engage, others can pull up to 10 amps (electrically assisted bendix). All depends on the starter solenoid.
    So long as the neutral safety switch, and clutch switch can handle the current required by the starter solenoid, then it's true, no need for an additional relay.
    Key point there being, that the switches must be rated to handle the solenoid load. I'm pretty sure the N switch in my T5 can handle the load, but I was not convinced the clutch switch I have could. It looked pretty light.
    I don't know anything about the TKO neutral switch load rating. But I would not be surprised if it was not designed for solenoid loads. The newer trans are often designed for computer controlled cars. It's very possible that switch was designed to only interface TTL logic.

    Additionally, it can also simply depend on your wiring needs.
    In the case of my install, I already needed a relay for the starter-kill feature of the security system I installed, and because the s2k push button can't take the solenoid load.
    So, I opted to use a single relay that was controlled by all systems (start-button, security, clutch, neutral, hidden override). It greatly simplified the wiring, and became a single point of failure, and a single point of diagnostics too.
    Last edited by skidd; 03-12-2019 at 09:30 AM.
    2016 MK4 | '99 Explorer 5.0 | E303&600cfm carb | T5z + 3.55 | 3-link | SN95 | PB/PS | FR500 17" 315&275 |

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