Thread: Universal Ignition switch--Wiring question

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I have a vehicle that has NOTHING inline (fuses or circuit breakers) to protect the electrical system.

I have a universal ignition switch. It has 4 labels on the back--"st--ign--batt--acc"
Which of these do I use to put a circuit breaker inline to protect the starting circuit?

Thank you.

Battery wire going to the switch gets fuse. Check your wire closely, a fuseable link wire is often used here in place of a fuse.

How heavy should the wire be for this?

What do you mean by"Check my wire"?

How heavy should the wire be for this?
The wire size depends on the load of your accessories and continuous equipment, but usually this is a 10 gauge wire. But the load determines the size, and high temperature insulation is needed.

What do you mean by"Check my wire"?
I'm assuming you have a wire that is going to the switch, if not disregard.

If this is a new build and you have no wiring in it, I suggest you buy a harness for it.

out of curiosity, could he not run a wire from battery to fuse block, and from fuse block to ignition switch? Thus eliminating need for an inline fuse.

If the wire is run to the fuse box and from there to the ignition, then the section of wire from the battery to the fuse box would be unprotected. With the load this wire must carry, protection is highly recommended. Sometimes on this wire a fuseable link is used instead of a fuse. Fuseable links can be difficult to recognize, often they look like a smaller wire has been spliced into the main wire (look closely for a labeled rating on the link wire). Fuseable links (as any fuse) should be placed close to the source of power, in this case it would be close to the battery or solenoid connection.

Usually the battery wire goes to the ignition switch’s BATTERY terminal, continuing from the ignition switch BATTERY terminal to the FUSE box constant on section. Fuse boxes usually have two (or more) isolated sections, with some sections controlled by the switch.

The constant on section is NOT controlled by the ignition switch, it gets its power from the battery, power is distributed through fuses and this section is usually used for headlights, tail lights, brake lights, horn, exc. (sometimes horn, headlights and other accessories are controlled through relays).

The ignition switch’s STARTER and IGNITION terminals usually connect to the starter SOLENOID and ignition COIL directly, they are usually fused individually (fuseable link wires near the switch). The ignition switch’s IGNITION connection will be on with the STARTER position, but the STARTER connection will NOT be on in the IGNITION position.

The ignition switch’s ACCESSORY terminal connects to the fuse box’s accessory section (isolated section) the power is distributed through fuses to the accessory items such as radio, windows, doors, wipers, exc.. The ignition switch’s ACCESSORY items will be on with the ignition switch’s IGNITION and ACCESSORY positions, but the IGNITION will NOT be on in the ACCESSORY position.

Hopefully this clears it up a little.

Perhaps this would help? With at least some of you're questions. I'm more of a picture or diagram kinda guy... maybe this will help some?

Thanks 34-40, the site will not allow me to post attachments?

[QUOTE=36 sedan;562438]Thanks 34-40, the site will not allow me to post attachments?;QUOTE]

Then send them to me and I'll put'em up for ya! If you need my e-mail, just holler.

That is a super- simplified diagram.
You'll notice it has no fuse protection for the ignition circuit.

Also, it does not show the alternator. The ignition voltage is most properly sourced from the main power distribution block, which also sources the sense wire to the alternator.

I read a really great article a while back which explained why the voltage works better that way (basically the alternator can accurately sense the voltage drop) but I have a habit of cleaning out old files, so I do no longer have the article.