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Switched Ignition Live Help


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#1 pcxr

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Posted 26 October 2012 - 11:51 AM

I require a few switched ignition lives, alternator sense and input to ecu. I phoned Westfield and because my loom is an early one it has no switched live.

Question is how do I install one.

#2 WellyJen

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Posted 26 October 2012 - 01:32 PM

What age is the loom on your car? If the ignition is switched on from the ignition switch, then it has a switched live. My car was originally just carburettors and Luminition Optronic ignition via a coil. This was turned on from the ignition switch.

When I added things like an ECU, alternator sense, high pressure fuel pump, injectors and so on to my car I made a separate loom for all the new equipment. This was connected direct to the battery via an additional cable with fuses and to earth also. The loom was powered up via a pair of relays, energised from the ignition switch, actually the old ignition feed to the coil. This meant that it wasn't trying to draw huge amounts of additional current through the ignition switch and overloading that circuit.

Jenny

#3 Dave Eastwood (gadgetman) - WSCC AO Rep

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Posted 26 October 2012 - 01:37 PM

Are you sure? As Jenny said, that sounds odd, could it be either you or Westfield have just misunderstood what you wanted?

How do you stop your engine once it's running, even if you've no ignition key and use a start button, you must surely have an ignition off switch?

#4 pcxr

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Posted 26 October 2012 - 03:54 PM

I made it clear that I wanted a switched ignition live for the alternator sense and fuel pump relay and he saida loom from 1996 will be early and have no switched live.

I was trying to id a switched live on the back of the ignition barrel that would prime the pump but 2 of the 3 wires were permanently live and the other only became live when the key was turned all the way to turn the engine over. I know esentially that one is switched but it wont prime the pump.

I have worked with switched lives and relays before in an old ford and the pump primed for 2-3 seconds when the key was turned to second position. Westy doesnt do this, nothing happens when keys at second position and if i wired it to the permanent lives it obviously runs constantly which isnt right.

I realise now that the MBE ignition ecu im getting should prime the pump but not confirmed. That aside I still need a ignition sense for the alternatorand switched live for ecu.

#5 Dave Eastwood (gadgetman) - WSCC AO Rep

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Posted 26 October 2012 - 04:08 PM

Does turning the ignition key to the off position stop the engine? if so, one of those three wires is the switched live. (One will be permanently live -the feed from the battery position, the other - usually thinner gauge wire that runs to the starter solenoid - often white with a red trace IIRC, is the one that goes live in the starting position.

If you have to use a switch to stop the engine, (unless it's an FIA cut off switch) then the ign. live will be one side of that switch. It may well be, if you're on an ecu, that you don't have a conventional high current switched live circuit - just a low current, thin wire that goes to the ecu's power relay. But here needs to be something in there somewhere!

#6 Dave Eastwood (gadgetman) - WSCC AO Rep

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Posted 26 October 2012 - 04:27 PM

A quick check back through old build manuals seems to suggest the ignition switch should have a brown feed from the battery, White feed out (swiitched) to fuse box and white with red trace to starter solenoid.

Of course it's a kit car, so the reality could be anything!

#7 pcxr

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Posted 26 October 2012 - 05:52 PM

Yeah thats what ive got the three you mention, so that means theswitched live is the white one and therefor the one i need.

#8 pete g

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Posted 26 October 2012 - 05:56 PM

you should have two sets of fuses .one set are battery live. the other set should be ignition live.



fuel pump are normally controlled via ecu . alternater switched live can come from any of the ignition live fuses.

#9 Dave Eastwood (gadgetman) - WSCC AO Rep

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Posted 26 October 2012 - 06:04 PM

Yep, not sure if the earlier cars are the same, (couldn't find as much fuse box info). But in later cars the white ignition live circuit connects to one side of the ignition live fuse box. Each circuit then has its own, appropriately sized fuse, and the feeds out are on green wires.

As Pete said, the second fuse box is the one with coloured wires in and out and is the permanently live box, feeds lights, indicators etc.

#10 pete g

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Posted 26 October 2012 - 06:08 PM

my 1992 car is wired like it .and cant see how they can be that different . you need perm 12v circuits and ignition circuits on all cars. :t-up:

#11 Dave Eastwood (gadgetman) - WSCC AO Rep

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Posted 26 October 2012 - 06:15 PM

Yep that was my point earlier, even if the ignition switch on the column has been bypassed to allow for a starter and toggle style ignition switch somewhere. There still has to be a switch for the ignition live circuits somewhere on the car, or you couldn't stop the engine!

#12 Meakin

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Posted 26 October 2012 - 09:05 PM

On mine, very old 1992 loom it has 1 fuse box (8 fuses). You have loops that connect lives for different feeds. Ie Only 1 switched live (white) and 1 permanent live (brown), this is then looped from fuse to fuse to create parallel circuits (mine is at the top of the fuse box). This then feeds the 8 fuses 3 are the circuits that require permanent live: lights, starter/horn (i think - but could be wrong), and radiator fan. The other 5 are switched they feed to both green and purple wires. what they connect to is another thing. I think they are heater fan, windscreen wipers, ignition, fuel pump, indicators/other ignition switched lamps (reverse) BUT could be totally wrong on what they connect.

I simply had a series of wires to extend to fit a fuse box and found this to be right. What you need look at pcxr is the fuse box to find your switched lives and permanent lives.

Hope this has helped in some way.
Paul

#13 Paul D Turner

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Posted 27 October 2012 - 07:46 AM

What age is the loom on your car? If the ignition is switched on from the ignition switch, then it has a switched live. My car was originally just carburettors and Luminition Optronic ignition via a coil. This was turned on from the ignition switch.

When I added things like an ECU, alternator sense, high pressure fuel pump, injectors and so on to my car I made a separate loom for all the new equipment. This was connected direct to the battery via an additional cable with fuses and to earth also. The loom was powered up via a pair of relays, energised from the ignition switch, actually the old ignition feed to the coil. This meant that it wasn't trying to draw huge amounts of additional current through the ignition switch and overloading that circuit.

Jenny


Exactly my original scenario and I did exactly this with mine. The only difference was the new live was taken from the switched side of the battery master switch instead of the battery and I put a fuse in this live immediately after the battery switch, don't want a fire.

#14 Norman Verona

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Posted 28 October 2012 - 09:19 AM

Do you think


loom from 1996 will be early and have no switched live.


Should read


loom from 1996 will be early and have no SPARE switched live.



#15 Dave Eastwood (gadgetman) - WSCC AO Rep

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Posted 28 October 2012 - 10:13 AM

Knowing how primitive some Westfield wiring has been, I took it as possibly being a step further, (unless I've misunderstood you Norman), I took it as possibly meaning, everything but the actual ignition itself was "battery live", let's face it, the lights already are, and that only really leaves horn, wipers etc. I'd still be slightly surprised if this was the case, but it's not beyond the realms of possibility.




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