Missing Ignition Part . . . . Help!

[S_Beaudry]

At a loss for the correct term here . . . .

I guess I need a "relay" or something that is between the battery + and the ignition key switch which is rated at 15 amps that will cut down the 750+ amps from the battery +.

I am trying to do some out of car testing, and not using the fuse box in the car.

Are these "relays" just generic?

Is there one usually built into the fusebox when I wire it that way?


Any help greatly appreciated . . . . .

[John Poling]

S_

A relay does not "cut down" the amperage from the battery. The only thing the rating on a relay tells you is that more than 15 amps pulled through the realy could cause it to stop working correctly. If you do not know the amperage a certain component pull, you have to take power (watts) into consideration when figuring whether or not a relay will depedably work or not.

P=Power (watts)
I=Current (amperes)
E=Potential (Voltage)

P=IxE
I=P/E
E=P/I

A 12 volt cars voltage supply is normal at 12.7 volts from the battery.

OEM headlights or most foglights are generally rated at 55 watts.

Therefore using the appropriate formula from above one could deduce that the current draw would be equal to about 8.66 amps for two headlights on their low beams.

This is just an example for you to use.

The 750 amp rating on a battery is just basically letting you know the "Power Ability" of the battery, kind of like your typical house circuit breaker box has a 100 or 200 or whatever ampere main on it. This is the amperage value that you wont exceed by supply.

What are you testing?

John

[S_Beaudry]

In my haste, I did not see the ignition key switch was only rated at 15amps.

After connecting the ignition key switch to the battery ( nothing in between the two ), I think I fried the key switch.

The connection that only had power when the keye was turned to the start position, now has power all the time, therefore I think I overpowered the key switch.

What part goes in between the battery + and the key switch to reduce the power?

Did I fry the switch, or is it just bad? It did work, but then it went bad, was it overpowered?

[John Poling]

S_

In all of the designs I am aware of, there is nothing between the ignition switch and the battery except a fuse.

If you fried an ignition switch, it was probably defective unless you splice some kind of a high current drawing item inline without a relay. Generally speaking, you would not be running more than a few amps through an ignition switch, instead, you would use it to supply voltage to a relay which would only draw milliamps through the ignition switch.

John

[Ron61]

S_,

I just looked to be sure on my 69 factory wiring diagram and there is nothing between the switch and battery. You can use a ballast resistor to drop voltage, but the 12 volts through your switch should go to your solenoid to operate it and that will cut the heavy current through to the starter. Make sure that you don't have a short somewhere that is pulling to much current through the switch. The solenoid is just a heavy duty relay. Make sure it hasn't shorted the primary winding straight to ground. And as you stated, a bad switch is a possibility also. Even a piece inside the switch could have came loose and be shorting. Ballast resistors are normally used with the old points and coil distributor set ups.

Ron

[S_Beaudry]

Does the solenoid need to be grounded right back to the battery, or can it just go to ground on the chasis?

The wire back from the switch to the post on the solenoid that supplies the "momentary" power to the starter, does that go to the small lug that says "S" or the one that says "I" ?

Just want to be sure of this so as not to short something out!


Anyone . . . .

[Michael C Henry]

What got grounded .The switch shouldn't have any electrical contact from an inside contact with the outside of the switch when the switch is operated it makes connections internally with the terminals.Unless the contacts were no longer in there proper positions which means the switch is no good anyway.
. Check the switch by dissconnecting all wires, remove the switch from the dash .Use a multi meter on the ohms position .connect one probe to the" Bat" terminal,the other to the metal outside of the switch there shouldn't be a connection.Then operate the switch and see what terminals get connected in which positions of the key.(Off )no connections ( ignition position) ignition and accseesory terminals should be hot .(Start) is the spring loaded podition start should light up while being turned, Ign should stiil be hot. In (accessory position) battery and accesory should be connected.If you have a connection to the switch housing ,the switch is junk. If connections aren't where and when they are supposed to be its junk. Switches are realitave cheap. A Circuit breaher between battery and switch could be saver.Butt If it fried internally ,what did you have connected to draw that much current?

[John Poling]

S_

If you are holding the starter solenoid in your hand as if mounted to the firewall. In other words, the solenoid cylinder is between you and the mounting bracket with the 2 small terminals pointing at you. The cable from the battery should be connected to the large terminal on your left side and the starter cable connected to the one on your right. The wire coming from the ignition switch to the starter solenoid should be connected to the "S" terminal and the only thing that should be connected to the "I" terminal is a wire that goes from the starter solenoid to either your ignition coil (non Duraspark II ignition) or to your ignition control box depending on which ignition system you are using. The "I" terminal is not used on all systems. This is where you need a pin out for the system you are using.

Does this help? If not, please clarify more here.

John

[S_Beaudry]

Originally posted by John Poling


S_


Does this help? If not, please clarify more here.


John

Yes, everybit of info does help. . . . .

A quick trip over to Autozone and I found a new ignition switch for $8.95, brought it home and wired it the same as the old one, and it did work fine.

So . . . either the switch was bad, or I accidently shorted it out by myself.

Thank you for the help and the insight!

[Michael C Henry]

If its a new solinoid ,it should have instructions, if not hope the terminals are marked. They make so many solinoids that all look the same but are different .I've seen solinoids that are for forklifts. The second small terminal is a ground that is connected to the alternater. It works as a starter safety that keeps the starter from activating while the engine is running.But if you ask for a starter relay solinoid for a mid sixties Ford ,the two large (5/16") terminals are (battery)power in and (Starter ) switched Power out,the two small terminals are the trigger or (switch) and (Ignition ) is for resistor bypass that would by pass the Oem resistor that supplies a cut down power to the coil. for a full 12v while cranking. If there is no provision for a ballast resister in the coil power supply then the bypass is not going to gain you anything.On a fiberglass car you will have to run a ground wire from the solinoid metal mountimg bracket to the ground system to operate the electro magnetic switch.
My light blue solinoud was operating just fine when I took the car apart.The first time I tried it after all the work in worked it operated one time and the electro magnet quit, the connection was broken internaly. The solinoids are riveted together and repair is not an option. Heck, they arne't that expensive.My difficultty was finding a color that I liked and the same distances of the mounting bracket to large power in terminal. I ended up with a light grey BW solinoid that had a different way the bracket came off the body but everything worked the same.l