Kill switch wiring

[Z3_GoCar]

GCR 17.27: "The master switch shall be installed directly in either battery cable and shall cut all electrical circuits..." (my emphasis) I was describing above with this requirement as an assumption.

You don't have a choice: the battery must be completely isolated from the rest of electrical system. If you did it as you describe, then the remainder of the car's electrical system is still getting juice from the battery.

....

[/b]

Greg,

Though I'd mention one exception which is electrically actuated fire systems must be hot at all times even when the BCS is off. If it's a pull cable like mine then all dead is good.

James

[raffaelli]

Can the lines which pass through the fire wall be continuous or do they need to be interrupted by one of those bulkhead terminals? I poked around a bit but could not find the answer. Should the line be continuous, what is commonly used to seal the opening?

[joeg]

A properly sized rubber grommet.

[Greg Amy]

Can the lines which pass through the fire wall be continuous or do they need to be interrupted by one of those bulkhead terminals?

AFAIK, there is no regulation in regards to that. Use your best judgment and best practices. - GA

[raffaelli]

I am suprised that the rules are not more clear on what the requirements are.

I see on the Summit site some pretty neat grommets. But....$18 each??????? :eek::eek::eek:






I think I will stick with the $10 assortment pack.

[Flyinglizard]

You could break the negative side. WFM. MM

[Streetwise guy]

Just to make life a bit more interesting, most Bosch alternators are internally regulated, and will continue to charge unless you disconnect the main power feed, which will have unpleasant effects on the alternator diodes. I have hooked my kill into the trigger circuit on the main efi relay (Dodge calls it the ASD relay), which on my Neon kills alternator field, ignition and injector pulse. The advantage to using a low amperage circuit like a relay trigger wire is there is no chance of burning up the kill switch. The disadvantage, as I discovered when I installed an unknown used kill switch, is that not only does the car quit charging if there is a problem, the injectors and ignition quit too. Post up the wiring diagram of your cars injection relay, and I'll show ya which wire to cut.

[JimLill]

as for going through the fire wall......... make a hole the size that heater hose fits snugly through and use that for your cheap grommet, with the batt+ through the hose. $.25 fix

[keilysmith]

It can be as easy as simply adding a little child and a transient (normally open) switch. Look for the sign "hot" exhaust - is a cable that goes from the center of the leg volume control, and ends at the end "tab on the outlet. Now, add a cable, for example, during the volume control, and welding of this cable to switch (either legs up). Then another wire bond for the remaining leg (the two who want to use) the switch and solder the other end to ground.

[Flyinglizard]

If you break the neg side and break the fuel pump ground wire at the same time, the car shuts off, fuel flow stops , and the whole wire system has better crash resistance. Smashing the ground wire into bodywork wont start a fire. This also avoids the big hassle of the alt contining to run the car.
The Bosch alt are often self exciting/ firing at around 3200=4000rpm . Check yours. Most will start without a light/exciter wire. For the few that need a light , I use two side marker light sockets and bulbs. The diode is in the alt , glowing the bulbs, key on engine off. When the car/alt fires, the lights go out.
I use this method for the ministock that needs to make a vacuuum rule. I need the alt load to increase the vacuuum so that I can use more cam.
I use two bulbs, because if one burns out the alt will not fire and the car wont make vac, costing me a DQ and money..
FWIW, many race cars have the starter power bypassing the bat break. The break switch does not like the high amps for very long and often results in a no start on the grid with 2 to go.
I dont condone this wiring, but my endurance car has the bat switch that can be bypassed really quickly.
HTH, MM

[JohnRW]

It can be as easy as simply adding a little child and a transient (normally open) switch. Look for the sign "hot" exhaust - is a cable that goes from the center of the leg volume control, and ends at the end "tab on the outlet. Now, add a cable, for example, during the volume control, and welding of this cable to switch (either legs up). Then another wire bond for the remaining leg (the two who want to use) the switch and solder the other end to ground.

kielysmith = [ame]http://www.youtube.com/watch?v=G6D1YI-41ao[/ame]

[Greg Amy]

As long as we're sullying the topic...I'll match your Hungarian with a Turbo Encabulator...

[ame]http://www.youtube.com/watch?v=rLDgQg6bq7o[/ame]

...and raise you a Retro Encabulator.

[ame]http://www.youtube.com/watch?v=RXJKdh1KZ0w[/ame]

(it's funny as hell when John and I think of the same things... )

[tom91ita]

try looking at how i wired my 86ish honda crx.

http://www.flickr.com/photos/tom91it...7603191663037/

basically, i tried to show on the car's wiring diagram and the switch wiring diagram how they relate to each other.

so connection "A" or "D" on the switch is shown as "A" or "D" on the wiring diagram.

hope this helps. btw, i have done the annual tests as well race weekend tests and never hurt the alternator. (weekend tests are wondering why the car won't start when i arrive at the track and then remembering i keep the master switch off in the trailer......)

[mossaidis]

Posting for a friend that is prepping his car for SCCA in NARRC ITE..

We're trying to wire the killswitch. He has a late 1.8T VW motor in a 84 Scriocco.

"The problem with the altenator is that it takes it's feed for the exciter wire directly from the battery cable wire from the back of the car. I will asssume I have to cut all power to the main feed cable before the altenator? Not sure how to isolate it completely from the system so the car shuts off when switched."

[Greg Amy]

How "late" of a VW 1.8t?

Most VWs use Bosch alternators with internal field circuitry; ergo not even with the sheisrocket would there be a field wire to bisect. In that case, I'd recommend bisecting the wire from the battery to the starter with the main cut off circuit, then bisecting the main ignition wire through the secondary normally open circuit of the switch ("Z or 2" in the diagram on page one.)

For the 1984 Scirocco, the secondary wire to bisect would be the "15" or "switch on" circuit that supplies power to the rest of the car, a 16-gauge black wire coming off the ignition switch. Cut that wire and the car dies.

GA

[GTIspirit]

I encountered similar situation on my '87 VW GTI 16V when wiring the kill switch. Alternator keeps the engine running quite fine when battery power is cut..... So I plan on interrupting the "T15" to the ignition because that will kill the spark which will in turn kill the fuel pump. Most vehicles should have some kind of fuel pump enable that's controlled by the ignition. So when the engine stops running the fuel pump stops pumping, no need for a separate fuel pump cut. This should also dissipate the charge from the alternator so there is no risk of blowing the regulator with a sudden shutoff of the alternator output.

[dhrmx5]

This is a subject that is a real pain to me. Yet another vaguely written rule in the GCR that is subject to interpretation.

I have always wired my switches to kill battery power and the fuel pump. Cars will run just with just a battery or an alternator but if you take away the fuel I guarantee the engine is going to die. Sure, it takes a few seconds for the engine to shut off and the alternator to lose it's energy but at that point in time ALL circuits are dead and there are no fuel lines pressurized to 60-90 psi just waiting to burn through or crack and cause a flash fire. Fuel pressure is gone because the engine burned it off. Certainly a much safer scenario for the turn worker who is trying to assist you or put out an underhood oil/gas fire.

Why is the rule poorly written? There are no criteria for time, testing, or wiring for most cars. The fact that the GCR is specific about wiring a SRF but not any other vehicle leads me to believe there are options as to how the results are accomplished. The way I wire my car has all circuits dead with the car running after a few seconds and the circuits are all dead with the car not running. Given that the rule simply states that all circuits must be cut would mean that my wiring accomplishes that goal.

[CRallo]

best first post ever?

This is a subject that is a real pain to me. Yet another vaguely written rule in the GCR that is subject to interpretation.

I have always wired my switches to kill battery power and the fuel pump. Cars will run just with just a battery or an alternator but if you take away the fuel I guarantee the engine is going to die. Sure, it takes a few seconds for the engine to shut off and the alternator to lose it's energy but at that point in time ALL circuits are dead and there are no fuel lines pressurized to 60-90 psi just waiting to burn through or crack and cause a flash fire. Fuel pressure is gone because the engine burned it off. Certainly a much safer scenario for the turn worker who is trying to assist you or put out an underhood oil/gas fire.

Why is the rule poorly written? There are no criteria for time, testing, or wiring for most cars. The fact that the GCR is specific about wiring a SRF but not any other vehicle leads me to believe there are options as to how the results are accomplished. The way I wire my car has all circuits dead with the car running after a few seconds and the circuits are all dead with the car not running. Given that the rule simply states that all circuits must be cut would mean that my wiring accomplishes that goal.