Technical Can You Use a Brake Light Switch for a Nuetral Safty Switch?

Can You Use a Brake Light Switch for a Neutral Safty Switch, will it carry the load?

 

The load is not the problem. The switch is normally shut, held open when the brake pedal is up. Pushing the brake pedal lets the plunger come out, allowing the current to flow.
You want a switch that is opposite of that , I believe.
Normally open, held shut when in reverse. Good Luck

 

Any switch can be used with a relay and if you use a five tab cube relay you can wire it to function anyway you want...


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Unless i misunderstand what you wrote, you are backwards. most brake light switches are normally open, closing when brakes are applied to complete a circuit to turn lights on. Same as Neutral safety, normally open closed in park or neutral.

 

You can use a push button starter switch but, it'll only work in park.

 

A 50's plymouth lever type brake light switch is normally open , like mentioned , you may need an additional relay in the circuit ...

 

You could use it but would need a tab on the clutch pedal to depress it when you push in the pedal. That was the way my OT 69 Firebird was from the factory. IIRC they used the same switch to do each function.

Just looked it up. They actually had a lever type of switch like some of the old GM cars used.

 

I did misunderstand, I thought he was wanting a switch to turn on the backup lights when it was in reverse. What I said about the function of the brake light switch is correct, as I understand it. The "normal" position of the switch is where it sits when it is un actuated, even though we consider the normal position of the brake pedal is not pushed, when its sitting there in that position, the plunger is pushed in. Its a normally shut switch.

 

I am reading some confused sounding answers here.

All the brake light switches I’ve seen on cars connect the two wires when the button is not pressed- so the circuit is open when the brake pedal is resting up and pushing the switch.

This kinda switch would work as a NSS but I would use it as the ground leg on a bosch relay. Then feed the input with the starter switch/button. That way you can hit start all you want but it won’t crank unless the brake is pressed. That would be similar to a stock setup where the NSS is a ground switch that is engaged only in N or P in the trans or an aftermarket shifter.

I guess you could also use the key as only the run circuit and divorce the crank circuit. Then feed the starter button from the brake light circuit- you can hit start all you want but it won’t start unless the brake lights are on. This way would avoid a fancy modern bosch relay.

 

What I have going on is a Tremeck 500 (5 speed) WITH a short shifter location, when you move the shifter to a forward location you loose the factory Tremeck NSS, you have to plug it off. First choice is to mount posted pic of a brake light switch to mechanically operate as a NSS on the clutch pedal under dash. I think you have answered my question, NOT a good idea without a relay. If I have to buy the switch, buy a relay I might as well get a true NSS off a Mustang? that will not need a relay?

 

I would give Lokar, the shifter people and purchase the small button type switch from them.

 

It may be a little tricky using a simple switch such as that as it has to be activated in neutral, if it’s a standard and it’s on the shifter the range of the switch would have to go from 1st and 2nd and neutral and 3rd and 4th and neutral. A micro switch with a little lever would be a better choice or a ball switch. If on a automatic, it would need to work in park and neutral. Those would require some trick stuff to work properly. If you are going to use it as a “ safety” switch on the brakes or clutch it should be no problem.






Bones

 

Napa has a truck/tractor starter button that has a 30 amp rating, no relay required.
Also has a threaded neck on one end, bracketing made easy...Under $20? Last I checked.

 

I think it was a mopar with a 727 where the switch just opened the ground at the solenoid so it would not start. A simple rocker switch will work. You will need to construct a bracket.

 

I'm so confused... not sure if we are saying different things or the same...

 

The same, only different.

 

I am using the same switch for Brake light and Clutch switch, ( Napa #SL169 ) however it was originally used for Brakes.
GM used a heavier switch for the Clutch switch. Power was routed through the ignition SW, Clutch switch to the Start Solenoid, which requires higher current than the brake lights. Manufactures don't generally give current capacity of the switches but brake lights are wired with 16 or 18 ga wires. The Start wire on a Solenoid is 10-12 ga. with a lot more current capacity. If you decide on using it for a Neutral Safety Switch, use a 30 amp relay to power the solenoid, or the switch would not last very long.

 

Ok, the older lever type switches on -55-9 Chevy trucks (others too) are spring loaded. The switch is on the closed (current passing/short/etc, however you want to say it) as you pull the switch out of the box.

This would be considered a NC (normally closed) switch.

When you install the switch you have to pull the lever back and put it behind the pedal rod. This opens the switch (stops current flow like cutting a wire).

So when the pedal is at it at-rest position, no current can flow through the switch, when you depress the pedal, the spring loaded action follows the pedal movement and "closes" to allow current to flow and light up the brake lights.

Most of the later model vehicles are similar, but the switch actuates a micrositch built inside, and you can hear a little "click" as you depress the pedal and the switch closes.

Personally I don't see an issue using this type of switch on a manual transmission actuated off the clutch pedal.

I think it'd be a pain to try to make it work in an automatic tranny though.

 

Now I understand my misunderstanding.....those switches are normally closed but held in the open position normally!!

 

Just like Mike said, the same but different, little sideways and maybe backwards too

 

Configure it to work with the clutch pedal, then you don't have to be concerned with adapting anything to the transmission shift mechanism. Both normally open and normally closed types of switches can be used, you just need to build the switch activating clutch linkage accordingly.

If you've got a hydraulic clutch then plumb in a hydraulic brake switch.

 

I have a pressure switch activated by my hydraulic clutch to complete the starter circuit. The original switch lasted a couple years the new ones don’t seem to do as well. One day I’ll get around to wiring in a relay. Until then I can change them out in about 2 mins.

 

Pollak ball switches here:

http://products.pollakaftermarket.com/category/precision-ball-switches

Many useful options, including Lokar’s use of them as NSS and backup light switches.


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I can see the concept of the neutral switch on the 5 speed but have driven GM stick rigs with the clutch pedal since Dec 68 When I got home from Nam and picked up my special order 69 Cutlass with 4 speed and am so used to it that I never consider putting a rig in neutral to start it unless I am working on it. Either way the rig won't start in gear and that is what you are after. The other option is a push button you have to push with your left hand while turning the key with the right that makes you think about what you are doing and either have it out of gear or push in the clutch.

 

Alot of microswitches with an arm or leaf on them suitable for this application have 3 terminals. A common, NO and a NC. Easy peasy! And as said, wire it through a relay if you have an amp draw more than the switch is rated for.

 

Thanks Al's.C.D.T those can intimidating if you don't wire them all the time!

 

Just to be clear, your relay schematic prevents the engine from cranking unless the brake is depressed?

I like to save this kind of stuff for future reference...

 

Right. A brake light switch is Normally Closed, and is held open by the brake pedal at rest. Press the brake pedal, the open switch closes, providing 12V to the lamps.

This circuit provides 12V to close the relay, enabling the ignition switch to crank the starter.

You could adapt this to a clutch pedal switch for a stick car, or a transmission mounted Neutral Safety Switch.



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I probably wasn't clear but yes I am planning on mounting it on the clutch pedal. Whether it's opened or closed shouldn't matter as I can mount it over or under pedal center line of pivot shaft.................................................