Ignition Coil Current draw.

[Mudderoy]

Does anyone know what the current draw is for a 1998 Jeep XJ ignition coil?

I know, at least I think I do, that the voltage is 12 volts, and looking at the size of the wire the amperage must be pretty low, maybe less than 30 amps. Hmmm I wonder what fuse is used for the coil...

[4.3LXJ]

Why do you ask?

[Mudderoy]

Why do you ask?

One of the places to disable a vehicle. Fuel pump or ignition coil.

[Thomass]

One of the places to disable a vehicle. Fuel pump or ignition coil.

I did do it by interrupting, the power supplies (electronic relais) from the computer.
so this way the rig will not start at all. ( by some rigs you will get an fault code after the power is restored)
I also have a brake lock

[Mudderoy]

I did do it by interrupting, the power supplies (electronic relais) from the computer.
so this way the rig will not start at all. ( by some rigs you will get an fault code after the power is restored)
I also have a brake lock

Yea I was thinking about putting a relay in on the brake line. Break that circuit and you can't get the thing into gear.

[4.3LXJ]

If you are thinking about a simple switch, the ones you got will run a coil easily.

[Mudderoy]

If you are thinking about a simple switch, the ones you got will run a coil easily.

I was thinking of a relay, and I just wanted to make sure what the current draw was so I could match up the proper relay. Nothing worse than having a Jeep that I can't start because I didn't design something right. Oh and it wouldn't fail until the worse possible moment. lol

[4.3LXJ]

I would just get the heaviest one I could. I just bought a 50 amp a couple of days ago for around $8.50 including tax.

[Thomass]

I disagree with the heaviest relay, i simple formula tells me that there will bee no more than 4 amps on the wire.
V = I x R, where V = 12 Volt and R = 3 Ω explains us that I = 4 Ampere
3 Ω is the coil resistance (i did measured it)
so 5 amps will be more than enough.
bigger relays become in time slow-switching witch will create carbon/contamination on the contacts and this will produce a higher resistance. and that will be bad for the proper working of the coil.
I do use an electronic relay, it is able to switch hi current fast, and in rest (on or off) it nearly doesn't draw any current for it self.
see

http://docs-europe.origin.electrocomponents.com/webdocs/0034/0900766b80034042.pdf

[Mudderoy]

I disagree with the heaviest relay, i simple formula tells me that there will bee no more than 4 amps on the wire.
V = I x R, where V = 12 Volt and R = 3 Ω explains us that I = 4 Ampere
3 Ω is the coil resistance (i did measured it)
so 5 amps will be more than enough.
bigger relays become in time slow-switching witch will create carbon/contamination on the contacts and this will produce a higher resistance. and that will be bad for the proper working of the coil.
I do use an electronic relay, it is able to switch hi current fast, and in rest (on or off) it nearly doesn't draw any current for it self.
see

http://docs-europe.origin.electrocomponents.com/webdocs/0034/0900766b80034042.pdf

Thanks Thomass. It has been awhile since I messed with electronic formulas and I had forgotten that one from Ohm's law.

[4.3LXJ]

Mud. The reason I said what I did is that the small relays all have the same coil. Just the contacts are different. So it doesn't matter. But I would want heavy contacts on something that was critical.

[xj4life2]

Ohm's law is great but the fuel pump relay fits in your pocket and takes only a sec to pull it and without that it aint goin no where.

[Mudderoy]

Ohm's law is great but the fuel pump relay fits in your pocket and takes only a sec to pull it and without that it aint goin no where.

Too much trouble plus you get finger prints all over your girls sweater, and that's never a fun subject when you drop her off back at her parent's house.

[xj4life2]

Too much trouble plus you get finger prints all over your girls sweater, and that's never a fun subject when you drop her off back at her parent's house.

So thats why I keep gettin caught LOL LOL

[4.3LXJ]

So now you have to make a choice. The relay or the sweater. Which is it?

[Thomass]

Too much trouble plus you get finger prints all over your girls sweater, and that's never a fun subject when you drop her off back at her parent's house.


So now you have to make a choice. The relay or the sweater. Which is it?

Those fingerprints can be helpfully :)
check this out:
http://media.conrad.com/m/7000_7999/7500/7510/7516/751633_GB_00_FB.EPS.jpg

it is just an fingerprint actuated electronic relay
than it doesn't matter where your fingerprints will be :smiley-laughing021:

[4.3LXJ]

Thomas, this could inspire a whole new thread, or maybe just continue this in the motivational posters thread.