10 replies to this topic

[bunch1980]

From doing a search read lots and i think for me best thing is to have the negative side of coil switched. To do this do i need to actually cut the negative wire? and put switch inline? or does it simply connect to negative terminal of coil?
If it connects to coil terminal how is best to connect it? Is there only 2 terminals on a coil + & -?
I have later 93' Sprite that has the lucas part electronic ignition will this make any difference to how i do this?

And am i write in thinking i need wire and a switch rated around 20amps?

Sorry for all questions just dont want to fry me or anything lol!

[david@skeggyminis]

if you get an on/on switch and wire one on in the + side coil wire that would kill the coil power when the switch is moved
then you can get a red flashing led to wire up to the other side on
so one on engine will start no flashing light flick the switch will kill engine and put led on

[bunch1980]

if you get an on/on switch and wire one on in the + side coil wire that would kill the coil power when the switch is moved
then you can get a red flashing led to wire up to the other side on
so one on engine will start no flashing light flick the switch will kill engine and put led on

I see an on/on switch would that have 4 terminals on the back then? and im guessing i would need to cut in to + feed to coil under the bonnet some where then feed back in to bulkhead behind dash etc?

I see and the led will look like an alarm thingy flashing then to!

[david@skeggyminis]

yes on/on has 4 pins
take the wire off the coil + join a new wire to it run that wire to the switch then run a wire from the switch back to the coil +
for the led find a + in the fuse box run a wire to the switch then join the + led wire to he switch and the led - to the body

[bunch1980]

yes on/on has 4 pins
take the wire off the coil + join a new wire to it run that wire to the switch then run a wire from the switch back to the coil +
for the led find a + in the fuse box run a wire to the switch then join the + led wire to he switch and the led - to the body

I have done a diagram as i think these can speak a thousand words! only things im not sure off is how to know which terminals to use on
switch or would it be obvious?
and can the fuse box connection be any continual live 12v feed?

So hopefully when this switch is on the coil will not work so mean car wont start, i guess starter motor will still turn over?
and the led will flash!

Attached Files

•  COIL_diag.pdf   6.01K   60 downloads

Edited by bunch1980, 15 March 2010 - 01:54 PM.

[Ethel]

The coil creates a spark every time the contact breaker points open. The points (or electronic ignition module) are just a switch connecting the coil to earth. By adding a second switch to earth you can earth the -ve side of the coil even when the points are open - no break means no spark.

If your car is unlucky enough to be targeted by a thief with half a brain, the ignition will appear normal and hot wiring voltage to the the coil will have no effect.

_______________/ ___dizzy (earth)
coil -ve ------<
_______________/ __hidden switch (earth)

[bunch1980]

The coil creates a spark every time the contact breaker points open. The points (or electronic ignition module) are just a switch connecting the coil to earth. By adding a second switch to earth you can earth the -ve side of the coil even when the points are open - no break means no spark.

If your car is unlucky enough to be targeted by a thief with half a brain, the ignition will appear normal and hot wiring voltage to the the coil will have no effect.

_______________/ ___dizzy (earth)
coil -ve ------<
_______________/ __hidden switch (earth)

So are you saying I should add another switch also to - side of coil? or just on the - only side? just to really confuse the thieving toerags lol?

[Ethel]

It's your call, a simple switch to earth the -ve side of the coil will work and won't be immediately obvious as the coil and points will appear to work normally without cranking the engine.

For additional measures how about a fuel tap or battery isolator in the boot?

[bunch1980]

It's your call, a simple switch to earth the -ve side of the coil will work and won't be immediately obvious as the coil and points will appear to work normally without cranking the engine.

For additional measures how about a fuel tap or battery isolator in the boot?

Thats was my original plan to do -ve side as most said this was best use after i did a search not sure reason why -ve was best.

Im also looking at an alarm/immobiliser to but will be a cheapish one if my mate can fit it, but not 100% sure i want one.
and like you say the discarnect in the boot is also on cards once i get to moss here in Bristol! just hope i can get my discount to!

Edited by bunch1980, 15 March 2010 - 04:36 PM.

[Ethel]

The dis-car-nect is tidy, but you could use any isolator switch by just adding a fused bypass between the terminals.

[bunch1980]

Right ive got some 20a wire on way and some 15a fuses, first off to wire in my 12v accessory socket i know how to wire that in now phew! lol

Now will 20a wire and a inline 15a fuse be ok for me to go from -ve of coil and add a switch etc?

Just so im clear on this lol I need to cut the -ve wire to the coil i guess some where near bulkhead then im basically splicing in a switch in that -ve wire?
which when off will cut off the coil so car wont star, will it turn over still?

Attached a pdf. of where i think i need to cut wire as shown on wiring for carb models 1988 and mine is 93' sprite so hope got right diagram.
the wire i have shown goes from -ve coil to rev counter it shows all though i dont have a rev counter so where does it go?

Attached Files

•  coil_wire_copy.pdf   71.27K   39 downloads