Giacomo

I am at the Glen race and while going through tech discovered that the emergency cut-off does not shut off the car's running engine. It appears the powers that be will not allow me to run without a properly functioning cut-off.

The cut-off switch that was previously installed in the car cut the engine right away so, although I didn't know how it was exactly wired, I didn't worry about it. The old switch had started to fail so I had it changed as part of the prep for the Glen race. The shop that did the installation wired the ground through the cut-off and not the power. So when the cut-off is engaged the battery loses ground and supplies no power. But the engine still runs because the alternator is grounded independently just by the way it is mounted. After some discussion with the shop owner he suggested I use the secondary terminals on the cut-off switch to loop the coil power through the cutoff. I did this and it does effectively kill the engine right away.

I now have a cut-off switch that cuts the battery ground on the main terminals and on the small secondary terminal is cutting off power to the coil. It works but does anyone see any problems with this setup? The power to the coil will always be running through the switch as will the battery ground.

garrett376

You should get a 6-pole switch, so you save your alternator during the moments your engine is spinning down after the switch is thrown, as the power output needs somewhere to go. The 6-pole switch gives the alternator a resistor to shoot its last bits of electricity through...

garrett376

And most clubs require the positive to be cut off... by just cutting off the ground, if your car gets crunched, it may find a new ground (anywhere on the chassis).

Giacomo

Oh, I fully agree, I just didn't turn my mind to it how the cut-off was wired when I picked up the car and drove off to the Glen.

Giacomo

What is a 6-pole switch, where do I get one and how do I install one? After the race I will have the cut-off rewired to cut out battery power and also the main power from the alternator.

garrett376

Here is a write-up I did on installing a kill switch in a 964... it should give you the idea! It's the only way to go, in my opinion. Especially when my club does "spot checks" of the kill switch after races in the impound - the frequent testing of the switch will surely roast the alternator over time!

Here's the link:
https://rennlist.com/forums/964-foru...right-way.html

Giacomo

OK, the 6-pole connector is what I have, just that the ground is routed through the main terminals and not the main battery power, that should be easy enough to change, more or less. The coil is also routed through #2 secondary terminals. The #1 secondary terminals have nothing.

How does the suggested install actually save the alternator? Where is the last bit of power routed? What goest to the #1 terminals?

JerryW

Here is another writeup I did for the 944Spec guys

http://944spec.org/944SPEC/content/view/77/25

you should be using all the terminals on the switch.

schwank

I just triple checked my wiring on a 944 with a 6 pole.

Main poles
1) Red from battery
2) Wiring harness and main power

Secondary poles
1&2) Coil
3) Loopback to Main Pole #2
4) Runs to a resistor as described by garret. This allows the alternator to bleed current as he described. The other side of the resistor goes to ground.

Giacomo

Schwank,

OK on main poles and 1 & 2 secondary on the coil.
The 3) loopback to main pole #2, is that just back to the pole terminal? because that seems a little different than the wiring diagram.

APKhaos

Giacomo,
How did this all turn out? Hope you got to run!
FWIW, your shop need an a$$ kicking for wiring your kill switch that way. Seriously!

shiners780

This might help...

schwank

Giacomo, Jim's diagram shows it perfectly... that line shunts power from the engine harness to the resistor through the secondary circuit.

fatbillybob

You need a new shop.

Here is the source for the right switch
http://www.pegasusautoracing.com/pro...asp?RecID=1464

And how to wire it
http://www.pegasusautoracing.com/pro...asp?RecID=1464

A930Rocket

Link to wire it:
http://www.pegasusautoracing.com/pdf...structions.pdf