Ignition Switch Wiring

drewsky121 · Jun 22, 2016

I need advice from people who are smarter with wires than me (doesn't take much).
1995 Mustang, it is a track only car... that i like to occasionally have fun with on the back roads.
In order to race in NASA's AI class, which is what i'm working towards, i have to remove the steering wheel lock. in the process, i've destroyed my ignition cylinder/function (don't ask me what i did, i'm embarrassed to admit it). when i connect the battery, everything primes and turns on, and i can't turn it off or advance it to the start position.
My question: can anyone provide me a dummy-proof write up or guidance on how to wire in a rocker arm switch (one with off/run/start) to my ignition? i will be installing the switch in the center of the dash, and no longer using the key obviously.
Thank you for your help!

mcglsr2 · Jun 22, 2016

drewsky121 said:
I need advice from people who are smarter with wires than me (doesn't take much).
1995 Mustang, it is a track only car... that i like to occasionally have fun with on the back roads.
In order to race in NASA's AI class, which is what i'm working towards, i have to remove the steering wheel lock. in the process, i've destroyed my ignition cylinder/function (don't ask me what i did, i'm embarrassed to admit it). when i connect the battery, everything primes and turns on, and i can't turn it off or advance it to the start position.
My question: can anyone provide me a dummy-proof write up or guidance on how to wire in a rocker arm switch (one with off/run/start) to my ignition? i will be installing the switch in the center of the dash, and no longer using the key obviously.
Thank you for your help!

Challenge accepted! Give me a couple min to consult my wiring diagrams and work something up. I'll post back in a bit. Just to be sure, you want to completely replace your ignition cylinder & key with a button, switch or some combination thereof that will allow you to start the car, etc. Correct?

Also, please use a different color font - I don't know if you are using a normal web browser or tappatalk or something, but your font color is almost exactly the same as the background color on the page, making the text practically impossible to read without highlight it.

drewsky121 · Jun 22, 2016

you are correct sir! I want to completely replace my ignition key and cylinder wiht a switch.
Of note, i don't have accessories that run in the car... but.. i have my gauges wired into the wires that used to be my radio/hvac...so i'm assuming i may need to have an accessories switch as well?

sorry about the font!
Thank you very much for the help.. i'm lost and confused on this one on my own.

Andrew

drewsky121 · Jun 22, 2016

I love your Das Llama build thread so far... i'm upset i haven't seen this one before! I know that i will be stuck reading through this for quite awhile. excited to stay up to date with it!

ttocs · Jun 22, 2016

there are only two ignition wires other then the starter in the ignition harness. It would be a simple process to wire into them. Not sure what you did but the cylinder is really easy to swap out and not that expensive if that is all it is.

mcglsr2 · Jun 23, 2016

Alright, here you go. I opted to use relays to carry the current, as the fuses are rated at 40 Amps. Also, completely replacing the ignition switch while keeping all the electronics requires that we use a larger number of relays (8 in total). A totally stripped out race car, with no A/C or Heat, aftermarket cluster, no windows, etc. can make do with far fewer relays. I listed out what each relay powers - if it powers things you don't care about, just don't wire up that relay. Leave those wires alone.

Essentially you remove the wires from the OEM ignition switch and wire them up as depicted in the pics below. This, of course, means your car will be super easy to steal, as there will be no more keys. Also, this wiring is based on my 95 Mustang GT. Lastly, I *think* I am correct with what I've provided here. But please: inspect my work, critique it, ask questions, make sure *you* are comfortable that I got it right. I will be happy to answer any questions you may have. Also, if anyone else has a different way of doing this, or better way, please let me know, I'd like to learn from you may know.

With that said, on to the pics:

This is what the OEM ignition switch looks like, the wires, the color of the wires, etc. This is used to make it easier to identify which wires will go where. Be very careful with the wires, as a lot of them are the same color - and it does matter which PIN on the ignition they go, so be absolutely sure you note their position before cutting/removing them from the ignition switch:

Here are the functions: at minimum, you will want START and RUN. If you have no interest in running Accessories (like listening to the radio without powering the entire car) then you can leave ACC out. Up to you. This table lists out the functions, the Relay(s) they will use (with wires that will be "connected"), and what functions they will power. Feel free to omit any relay that powers something you no longer have or don't care about.

Simplified wiring diagram for START and ACC. For START, you must use a Momentary switch, SPST, Normally Open. When Pressed, Closed. For ACC, you must use a Toggle switch, SPST, Normally Open. When toggled, it will be Closed. If you want to use an illuminated switch for either of them the wiring will be slightly different as you will have to run a +12V feed from the battery to power the LED. It's not hard to do.

Simplified wiring diagram for RUN. You must use a Toggle switch, SPST, Normally Open. When Toggled, Closed. The stuff I said about the illumination above applies here as well.

And there you have it. That should do it for you. Let me know if you have any questions or if the above is confusing or whatever

drewsky121 · Jun 23, 2016

Wow, that was incredible. Extremely nice work!
So, my dilemma is, when i took apart the steering column, i completely damaged/removed the plastic piece that is moved by the turning of the ignition cylinder that essentially allows for the key to function. So, right now, its just stuck in run mode but when i turn the key, it does not advance it to start or off.
So assuming that i am leaving everything else alone, and in tact, and simply want to relocate my starter wires, i need to wire up B4 and P1/2 to two separate relays by simply re-routing those wires before they go into that harness? If i leave everything else in tact, shouldn't it still function?

ttocs · Jun 23, 2016

hitting the wires in harness should still power all your accesories the same way the switch did. Now you should be aware that there are two different types of ignition wires. True ignition and then a regular ignition. A true ignition will stay on while the engine is cranking, a regular ignition will shut off while cranking. This allows only the pieces that need power while cranking(ecu for example) to get all the power that the starter is not taking and shuts down things like the radio that do not need it. You can wire everything to retain power while cranking if you want, not sure what is left on this car but it is better to seperate things that do not need it.

Also the rule in wiring is you never tap into a wire with out testing it first even if its the same color. You might be amazed how often the same color is repeated or how often its wrong.

mcglsr2 · Jun 23, 2016

drewsky121 said:
Wow, that was incredible. Extremely nice work!
So, my dilemma is, when i took apart the steering column, i completely damaged/removed the plastic piece that is moved by the turning of the ignition cylinder that essentially allows for the key to function. So, right now, its just stuck in run mode but when i turn the key, it does not advance it to start or off.
So assuming that i am leaving everything else alone, and in tact, and simply want to relocate my starter wires, i need to wire up B4 and P1/2 to two separate relays by simply re-routing those wires before they go into that harness? If i leave everything else in tact, shouldn't it still function?

Are you sure the car is "stuck" in RUN? If it is, you'd be powering the entire car: fuel pump, IGN, radio, etc. Do you just disconnect the battery or something? And to answer your question, if you are happy with the current state of the car but want a START, then just wire up the START portion of the diagram. But I'm not sure I understand the current situation with what you are describing. Also, ttocs has a really good point about separating START and RUN, see below...

ttocs said:
hitting the wires in harness should still power all your accesories the same way the switch did. Now you should be aware that there are two different types of ignition wires. True ignition and then a regular ignition. A true ignition will stay on while the engine is cranking, a regular ignition will shut off while cranking. This allows only the pieces that need power while cranking(ecu for example) to get all the power that the starter is not taking and shuts down things like the radio that do not need it. You can wire everything to retain power while cranking if you want, not sure what is left on this car but it is better to seperate things that do not need it.

Also the rule in wiring is you never tap into a wire with out testing it first even if its the same color. You might be amazed how often the same color is repeated or how often its wrong.

Hmm, good points about START vs RUN. I will need to rethink/redo this. I didn't separate items between the two. I suspect a different set of switches will be needed, a toggle that has an OFF, RUN, and Momentary START. I will update my diagrams tonight.

drewsky121 · Jun 23, 2016

My current state:
the moment I connect my battery, everything turns on. The fuel pump primes and gauges work. I have nothing wired in the car but stock gauges and three aftermarket gauges (that are running off of the wires that were originally for the radio (one power line from the battery, one ground from the battery, but I tapped into the radio ignition switched wire for my gauges to turn on and then the illumination switch wire for the lights) turning the ignition cylinder does nothing. I cut the plastic link that moves when you turn the cylinder with the key. While the cylinder is not stuck in run, that switch controlled by the movement of the plastic piece is.

mcglsr2 · Jun 23, 2016

Ah - I think I understand. In other words, if you were to remove the key cylinder completely, the car would still be stuck in run cause that stuff there is all effed up.

Are you good with the current state of the car? Meaning having it stuck in run and having to disconnect the battery?

drewsky121 · Jun 23, 2016

Correct. I could remove the ignition cylinder and it would still be in run.
Also, I'd prefer to be able to leave the battery connected. I want to be able to run my fan and what not after runs and not have to worry about it being in run, charging the coil constantly, etc.

mcglsr2 · Jun 23, 2016

drewsky121 said:
Correct. I could remove the ignition cylinder and it would still be in run.
Also, I'd prefer to be able to leave the battery connected. I want to be able to run my fan and what not after runs and not have to worry about it being in run, charging the coil constantly, etc.

Okay. Well, if you think the switch is effed and not really fixable, then your best bet would be to cut all the wires and do something like what I posted with the relays and stuff - essentially completely bypassing your current ignition switch cylinder. Then you could leave the battery connected and stuff.

Let me put a little more thought into, and take into account what ttocs said - I'll draft up some new diagrams.

drewsky121 · Jun 23, 2016

mcglsr2 said:
Okay. Well, if you think the switch is effed and not really fixable, then your best bet would be to cut all the wires and do something like what I posted with the relays and stuff - essentially completely bypassing your current ignition switch cylinder. Then you could leave the battery connected and stuff.

Let me put a little more thought into, and take into account what ttocs said - I'll draft up some new diagrams.

Greatly appreciated. If I don't want the accessory position on the ignition cylinder to work, there is no need to wire up relay 8, correct?

mcglsr2 · Jun 23, 2016

drewsky121 said:
Greatly appreciated. If I don't want the accessory position on the ignition cylinder to work, there is no need to wire up relay 8, correct?

Correct. If you don't care about ACC, just omit it. You wouldn't need a switch or the relay.

drewsky121 · Jun 23, 2016

mcglsr2 said:
Correct. If you don't care about ACC, just omit it. You would need a switch or the relay.

So I'm not trying to be complicated. Just want to let you know that, but I can't help but look at it and think there is a simpler way. What would happen if I just created two relays for nothing but the ignition. I had my own power source from the battery and simply cut wires B4 and P1/2 and routed them through the switch. Meanwhile, I left everything else intact and still hooked up to the harness on the column. Would that work?

mcglsr2 · Jun 23, 2016

drewsky121 said:
So I'm not trying to be complicated. Just want to let you know that, but I can't help but look at it and think there is a simpler way. What would happen if I just created two relays for nothing but the ignition. I had my own power source from the battery and simply cut wires B4 and P1/2 and routed them through the switch. Meanwhile, I left everything else intact and still hooked up to the harness on the column. Would that work?

No worries, I fully expect questions.

When you say Ignition, do you mean the START function, or the RUN function? And you could do what you said - but then anytime you attach the battery your car is in RUN. If you are okay with this, then just wire up the START function. The problem will be stopping your car - you will have to disconnect the battery to do that. The problem you have is that the car is stuck in RUN. Or am I missing something?

The simpler way (though I'm still not too clear on how exactly it broke) would be to just get a new key cylinder from LMR, new ignition switch if that's what is broken, and re-install those guys. Then use the key and ignition cylinder/switch like normal, no new switches or relays necessary.

And it's deceptively not simple. The issue ultimately is that the key/ignition on a car controls *a lot* of stuff. Think of each relay as a "circuit." The ignition switch is solely responsible for making multiple connections to energize those "circuits" at specific times. If you are just wiring in a push-button start as some people do, it's simple, as you only need to deal with the START function. If you have a stripped out race car it's simple, as you no longer have 90% of the things that those "circuits" are powering and thus don't need to make the connections. If you have a regular car powering all those "circuits" and want to replace/replicate the functionality of the ignition switch, then it is more complicated as each of those "circuits" need to be addressed.

ttocs · Jun 23, 2016

as he said you will be cutting/integrating into the critical power circuits in the car. For this very reason I normally do not recomend first timer/diy types to install alarms/remote starts and that is basically what is going on here. Replacing the parts would be much easier/cleaner and you still have the security of the key

drewsky121 · Jun 23, 2016

Well, i'm not new to cars or wiring, i was not entirely sure how to wire this based on our harness and how it works. I've done everythign else to this car, but i understand.

as stated however, i can't replace it all without replacing the whole steering column. again, its not in the cylinder or ignition switch. There is a plastic piece that moves when you turn the cylinder that engages the different switches inside the column. it is also where the lock is for the steering wheel. in the process of removing the lock, i accidentally destroyed that plastic shaft, and did so while it was in the "Run" position, so its now stuck in that position.

You are correct however, because i wasn't thinking when i asked earlier. because i don't want all of the accessories to be on the moment i hook up the battery, i will have to put them all on relays and one master "accessory switch" next to the ignition switch. just a toggle switch, with the starter on a 3 position momentary switch.

ttocs · Jun 23, 2016

if your wanting to run the fan between runs or an electric water pump put those on a separate relay and switch. I can show you how to use a diode to isolate that relay so it will power up with the regular accessory switch, but then not power up all the accessories when you just want to run the fan.