420A Neutral safety switch

powellds2 · Apr 8, 2015

I'm wondering how this switch functions. Is there power going to it? Is it just something the ecu looks for before starting? Anyone know the specifics of it?

rtrocket59 · Apr 8, 2015

Its just an on/off switch. Let's just say its a normally closed switch in the neutral/park position for sake of discussion (don't know the actual off the top of my head).

When in park/neutral, the ecu will see voltage coming from the circuit and logic will allow the starter relay to be grounded when requested.

If the shifter is in any other position, the ecu sees 0v coming from the circuit and logic will not allow the starter relay to be grounded.

Actual operation may vary but that is the basic operating conditions for your average vehicle.

powellds2 · Apr 8, 2015

Do you know the actual voltage of that switch? I'm trying to find a better way of using my 2step/wot box and right now I am using the cruise switch which is at the top of the pedal travel, I'd like to use a switch at the bottom of the travel (like the neutral safety switch location) but the box I'm using needs to see 12v to and then 0v when triggered, or vice versa. I'm just wondering if there's any power running through that actual switch that my wot/2step can pick up on. If my memory serves me correct, I think I tried tapping into both of the wires for a signal for the wot/2step box, but was unsuccessful.

VelocitàPaola · Apr 10, 2015

The switch grounds the starter relay, so you should measure close to ground with it on (closed), and close to 12V with it off (open).

powellds2 · Apr 22, 2015

VelocitàPaola said:
The switch grounds the starter relay, so you should measure close to ground with it on (closed), and close to 12V with it off (open).

Happen to know which wire has the 12v? I've tried both for my wot box and neither works.

VelocitàPaola · Apr 23, 2015

It looks like it's a black/yellow wire, according to the FSM.

powellds2 · Apr 24, 2015

Tried it, I wonder why I can't get it to work... To get my 2 step/wot to work I had to install my own switch and run it straight to a 12v source. Of course the only mounting option was at the top of the pedal where I don't want it... I'm thinking about just losing the safety switch all together and just using it for my 2step/wot box only...

luv2rallye · Apr 24, 2015

Read carefully (sounds backwards but this is how it works): On the M/T (only) when the clutch pedal is not pressed to the floor and key is turned to Start, the "clutch pedal position switch" remains closed so the starter relay activates which DISABLES the starter (relay contacts open). It actually provides the ground to the relay's coil to activate it. When pedal is pressed to floor, the "clutch pedal position switch" opens which prevents the starter relay from activating so starter remains enabled (relay contacts closed). All this makes more sense when you realize the starter relay is a normally closed type (so activating it opens up the circuit to the starter while deactivating it closes the circuit).

You may not be able to use this switch because when open (pedal down) the wire going to the relay coil is floating so it is not a true power source (coil is between switch and battery). So it may read +12v on a meter but as soon as you draw any current, the relay coil will drop voltage. If you only draw a couple milliamps it may work if you're lucky but I wouldn't trust it. And make sure you press pedal all the way down (to open switch) before turning key to Start or you will get a voltage spike generated from the coil (due to collapsing field of stopping coil current) - of course that would be normal pedal operation though.

Since the starter relay is normally closed, yes you could unplug (or cut it's wires) the "clutch pedal position switch" and rewire it to fit your needs.

powellds2 · Apr 25, 2015

luv2rallye said:
Read carefully (sounds backwards but this is how it works): On the M/T (only) when the clutch pedal is not pressed to the floor and key is turned to Start, the "clutch pedal position switch" remains closed so the starter relay activates which DISABLES the starter (relay contacts open). It actually provides the ground to the relay's coil to activate it. When pedal is pressed to floor, the "clutch pedal position switch" opens which prevents the starter relay from activating so starter remains enabled (relay contacts closed). All this makes more sense when you realize the starter relay is a normally closed type (so activating it opens up the circuit to the starter while deactivating it closes the circuit).

You may not be able to use this switch because when open (pedal down) the wire going to the relay coil is floating so it is not a true power source (coil is between switch and battery). So it may read +12v on a meter but as soon as you draw any current, the relay coil will drop voltage. If you only draw a couple milliamps it may work if you're lucky but I wouldn't trust it. And make sure you press pedal all the way down (to open switch) before turning key to Start or you will get a voltage spike generated from the coil (due to collapsing field of stopping coil current) - of course that would be normal pedal operation though.

Since the starter relay is normally closed, yes you could unplug (or cut it's wires) the "clutch pedal position switch" and rewire it to fit your needs.

I completely understand. Thanks a lot for the info, now I know why it wouldn't work. Well, I guess if I ever stick a remote start on my car, I won't have to worry about the safety switch

No biggie anyway since I'm the only one who drives my car... Ever.

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420A Neutral safety switch

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