Help Please - installing kill switch track car

S

scubaanddreams

Member
2008 3.0si e86 (n52) (likely same for e85)

Starting with the basics.

There are three main battery red cables coming off the battery.

One runs along the passenger compartment and feeds the fuse box.

The other two run underneath the vehicle on the driver's side forward. It's a pretty good assumption that the big fat one feeds the starter.

Conventional wisdom would say that the smaller red one brings power back from the alternator, but I am seeing conflicting information. Does anyone have a no kidding explanation of the three reds coming off the battery.

Thanks.
 
Two go to the main power terminal in the engine bay (which then loops on to the starter) which is on the firewall at the back of the engine bay

The other goes to the fuse panel and then splits 4 ways from memory in the fuse panel
 
bigwinn said:
Two go to the main power terminal in the engine bay (which then loops on to the starter) which is on the firewall at the back of the engine bay

The other goes to the fuse panel and then splits 4 ways from memory in the fuse panel
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Thanks, when you say main power terminal in the engine bay what do you mean? Why two cables, I ask because it appears on the e90s the smaller one may power the dme and the larger the starter which then is connected to the alternator. So little online documentation I can find on 06-08 z4 n52 on this so any help appreciated.
 
Given that the cables are bigger than everything else, and red, can you not simply follow them round the engine bay? Removing the intake pipework should give you a clear line of sight.

@Liam22 doesn't pop on here very much these days, but he is a bona fide race car driver who competes (and mostly wins) in an E86. Pretty sure he can give you a definitive answer. May be worth doing a search on his previous posts to see if he's answered your question already somewhere in amongst them.
 
In the UK and FIA regs, the kill switch has to isolate the battery, so that switch would have to take any cables from the positive terminal, so I don't think it matters where the cables go to from the battery . We are also required to mark the battery earth strap with yellow or orange tape so the marshals know what to cut in an incident.

Note also you will need to protect the alternator with a resistive link or the sudden cut-off will damage it. It usually comes as part of the FIA isolator switch package.
 
Liam22 said:
I even drew diagrams! See page 9 :)
Click to expand...

Thanks, for all the haters I actually did do a search.

@Liam22 - Reference your drawing page 9 for the smaller cable - is the power distribution box the box that has several fuses and powers mostly dme components? Just outside the dme box. If so, that would be awesome.
 

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When I refer to the "power distribution box" in my line diagram I'm talking about the black plastic box in the corner of the engine bay.

The engine bay box with the +ve jumper post is unfused and runs to the battery and starter.

I've read this thread a few times and cannot see a clear question that relates to your objective.

Are you installing an FIA or Motorsport UK approved isolator? Or a simpler kill switch?
 
Liam22 said:
When I refer to the "power distribution box" in my line diagram I'm talking about the black plastic box in the corner of the engine bay.

The engine bay box with the +ve jumper post is unfused and runs to the battery and starter.

I've read this thread a few times and cannot see a clear question that relates to your objective.

Are you installing an FIA or Motorsport UK approved isolator? Or a simpler kill switch?
Click to expand...

@Liam22

I am in the US. Just to make sure I understand what you said you are saying your term of power distribution box' is the unfused box that is attached to the firewall - ie not what I showed in the picture above?

I am installing a kill switch.

Question would be on wiring (as-is, without relocating battery box). Either two pole or multi pole. I believe the alternator is connected to the starter which in turn is connected to the box on the firewall - so none of this is making sense to me.

There is also the fuse box in the engine bay that I linked above that mostly fuses dme components.
 

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scubaanddreams said:
Thanks, for all the haters I actually did do a search.
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Excuse me?
Bit touchy aren't you? Mr Trump been upsetting you all again? :rofl:

The only reference I can see to searches is me saying 'I' couldn't be bothered to search.

So I assume I am now 'all the haters'?

Please be aware this forum is NOT facebook.
 
enuff_zed said:
Excuse me?
Bit touchy aren't you? Mr Trump been upsetting you all again? :rofl:

The only reference I can see to searches is me saying 'I' couldn't be bothered to search.

So I assume I am now 'all the haters'?

Please be aware this forum is NOT facebook.
Click to expand...

Sounds good. I am not here to engage in buffoonery....I'd ask you to do the same please.
 
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enuff_zed said:
No not really. Just appreciate a little bit of politeness from a newbie. Don't come wading in with an attitude against people who actually tried to help.
Yours sincerely,
All the haters x x x
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How did you try to help, other than your snide comment which seemed to be directed at me about doing a search. Thanks again.
 
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enuff_zed said:
Given that the cables are bigger than everything else, and red, can you not simply follow them round the engine bay? Removing the intake pipework should give you a clear line of sight.

@Liam22 doesn't pop on here very much these days, but he is a bona fide race car driver who competes (and mostly wins) in an E86. Pretty sure he can give you a definitive answer. May be worth doing a search on his previous posts to see if he's answered your question already somewhere in amongst them.
Click to expand...
Kind of thought this may have been of some assistance?
Your thanks are noted and gratefully accepted.
 
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