KILL SWITCH, AGAIN

#21

Better diagram (no changes, but easier to read).

So, I am going to mount this to some very sturdy 1/4" steel plate on the convertible battery tray right in front of the junction block. There is a very handy ground for the resistor on the strut tower - no wire need be more than 6" long.

I’m then going to fish a 18" pull up to the black vent under the passenger windshield. I found a nice one on www.renline.com. This will keep everything dry that matters. I have heard of sad stories of ruined weekends from kill switches.

Thanks all - especially Bruce!

#22

Here’s the way it turned out… not too shabby :wink:

Natalie

#23

Let’s try this again…

natblack wrote:

[quote]Here’s the way it turned out… not too shabby :wink:

Natalie[/quote]

KillSwitch.jpg680x510

#24

Dude that’s sweet.

#25

That is a very clean install. I took a slightly different approach and wired the switch right into that panel by the wiper. Drilled and grommeted a hole to run the battery cable through. Used a replacement battery cable and some 12g wire to run from switch to the "engine side". Cut off the old battery clamps and used eyelet style cable ends everywhere, then sandwiched all the eyelets with washers and ran a bolt through and taped it over. Then used the original firewall clamp to secure it. There’s a photo, the green tupperware box and yellow wires are for my data acq. Please ignore the nasty big practice hole where I f’ed up.

#26

I did mine at the other end of the car…had to fill the hole anyway:

IMGP1282.jpg800x600

#27

Bill, thats as good a spot as any. Just needs an E sticker.

#28

Gasman wrote:

I put the sticker on after this picture was taken…

#29

That’s a nice clean install… we considered that location too! (Isn’t it amazing how many different ways people can accomplish the same thing?)
Natalie

M3Bill wrote:

[quote]I did mine at the other end of the car…had to fill the hole anyway:

IMGP1282.jpg800x600
[/quote]

#30

jblack wrote:

Ok, I’m slightly confused. Nothing new in that. :lol:
The alternator feed wire that you show going through 2 or optional 1, is that also connected to the main switch? The diagram makes it look like it is going around it. That wouldn’t work, would it?

#31

1 and 2 represent two other sets of contacts on the kill switch (in addition to the large main terminals)
1 behaves opposite to the main terminals and 2 (i.e. it is closed when the main terminals and 2 are open)

bruce

#32

That might be a helpful piece of info I left out. I got the "six pole" one from Bimmerworld (even though they call it 4 pole). - Search their site for "Electrical Cutoff Switch" As Bruce says, when you pull the switch, you disconnect the big lugs and the #2 lugs, and connect the #1 lugs. This is to protect the alternator and give the electricity that it produces as it quits spinning for the 1/10th of a second after you pull the cord. Many have said that this is unnecessary on a BMW of our vintage, but it took nothing to wire it, and there is a ground right there at the strut tower.

#33

I’ve got a simple two post switch, can I just attach both the main and alt leads to it instead of using a 4 post?

#34

no, as John learned earlier, the two wires have to be separated from each other in order for the car to stop running when those circuits are opened.
bruce

ddavidv wrote:

#35

I understand the diagram you have drawn up and the principle behind it, but from the electrical schematics for my 89 325i, at least, the “smaller” wire from the battery has nothing to do with the alternator. Thus connecting it to the resistor isn’t achieving what I believe it should be doing. From what I see, you’d have to tap into the “big” wire and direct it through the resistor when the switch is turned off.

Or an I just looking at something wrong?

#36

M3Bill wrote:

[quote]I did mine at the other end of the car…had to fill the hole anyway:

IMGP1282.jpg800x600
[/quote]

Ok I need to install my kill switch and a transponder and I like the look of where this kill switch is. My question is how will this work if it is raining out side or would there not be a problem?

#37

the circuit we have been discussing does not have the alternator shunt-to-ground function that you are thinking of (involving the resistor). A typical 6 post cutoff switch will have a large set of contacts that are Normally Closed, a small set that are NC and a small set that are Normally Open (all when the red switch is closed). For BMWs, you use the two sets of NC contacts for the large and small wires from the battery. The NO connection is typically not used but you can run a wire from the alternator to it, and then a resistor to ground on the other side of the NO contact if you want to provide that protective shunt function when the switch is opened (those contacts will close at that point).
cheers,
bruce

kioneo wrote:

[quote]I understand the diagram you have drawn up and the principle behind it, but from the electrical schematics for my 89 325i, at least, the “smaller” wire from the battery has nothing to do with the alternator. Thus connecting it to the resistor isn’t achieving what I believe it should be doing. From what I see, you’d have to tap into the “big” wire and direct it through the resistor when the switch is turned off.

Or an I just looking at something wrong? [/quote]

#38

I think you would want to put some rubber grommets at the body to stop a lot of water from leaking in. The switch itself should be pretty well sealed.
bruce

lt1_man wrote:

[quote]M3Bill wrote:

[quote]I did mine at the other end of the car…had to fill the hole anyway:

IMGP1282.jpg800x600
[/quote]

Ok I need to install my kill switch and a transponder and I like the look of where this kill switch is. My question is how will this work if it is raining out side or would there not be a problem?[/quote]

#39

OK guys, I started futzing with the kill switch today and might be a little confused on the wiring.

I took a zip wheel and cut the two large cables at the terminal block, against the fire wall…I learned within minutes that move may have made this job a little more difficult than needed. :laugh:

I should’ve just cut the large lead, the main battery cable on the left side of the block and left the block intact?

Anyway, it’s a done deal, the entire terminal block has been removed and I have the kill switch bracket mounted pretty much in it’s place.

My quandry is now that I have all the wires cut, I know that the large battery cable and the 4ga. cable from the starter will go to opposite main terminals on the kill switch. The two 10gauge wires that were “married” at the terminal block, the one ran in conjunction with the main battery cable will go on the left terminal for “2”…

OK, out of all the cables on the right (looking at the firewall, as you’re working in that area) the red ones, 3 or 4 of them I think…which ones need to be isolated from the main terminals if any? On the two black cables that were terminated at the terminal block, do either one of those need to be on the other side of the “2” terminal? …opposite the smaller of the two cables from the battery?

Have I confused anyone yet?? …I think I confused myself. :blink:

I guess to summarize my question, it’s easy to figure out what to do with the two cables on the left once you cut them, but there are about 6-8 of them on the right, which ones can I terminate to the main lug on the kill switch, along with the cable from the starter, and which one(s) need to go on the other side of terminal “2” on the kill switch?

Thanks for your help, I’ll be finishing this up after I get the motor back in and ready to start up again.

#40

just imagine you had only cut the two wires leading up to the terminal block and make the appropriate connections.
bruce