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I don't get it either. No matter what stage any of the switches are in, the potential doesn't change... so it does nothing.

You may as well connect a loop of wire in parallel with the wire that goes to the ECM.


But this one I like.



putting switched 12v onto the neutral switch is a good idea. Then you must flip the switch, and press the button.

Oh oh, what if we had a switch with two pairs of contacts, so it closes two circuits at once? Tada!

One part of the switch closes 12V to the neutral switch, which in turn closes the relay, and the other signal is sent though the relay simultaneously.

What I'm trying to say is the "Switched 12v" and "Your Switch" are the same button, closed at the same time, when the button is pushed.

By switched I mean by a switched source that's on only with the key, either ignition or accessory, just to there's no need to have power running to it all the time. You can use a double-throw-double-pole switch, that will do and work exactly what you describe, but not needed and way more wiring than you need.

K, you guys don't see it, so I'll see if I can visually show how this will work:

Think of this as a game. You need to get your signal from the ECU to ground, ANY ground. A RED switch means the switch isn't pressed, a GREEN one means it is. "Start" means the car is now allowed to start.

On a normal start, you depress the clutch and it starts, if it's not depressed, the switch isn't on, thus it can't start.


Now, after your mod, say you want to start the car, but the shifter ISN'T in neutral, the signal can't get to ground, thus the car can't start...exactly what you want to happen as your safeguard.


Now, with the shiter in neutral, the circuit is open, so it allows the signal to pass to ground, so the car will now be allowed to start.


If you guys can't see it now, than I give up...really.

but we know the ECM isn't wired like that... I think I need to try that out, because I kinda get it, and just see what happens.

Indeed, but for what we know, it's not being used at all, which still would make it work. We're not sure where the switch wiring runs and if it goes back to the ECU or not, but whatever it does, all we know forsure if that it goes to ground, and that's all that is needed.

Even if it's being used, it's a much safer option to wire it rather than tying in 12v and being worried it'll ground into the ECU, frying that pin or even the ECU itself.

Nd4SpdSe wrote:By switched I mean by a switched source that's on only with the key, either ignition or accessory, just to there's no need to have power running to it all the time. You can use a double-throw-double-pole switch, that will do and work exactly what you describe, but not needed and way more wiring than you need.

K, you guys don't see it, so I'll see if I can visually show how this will work:

Think of this as a game. You need to get your signal from the ECU to ground, ANY ground. A RED switch means the switch isn't pressed, a GREEN one means it is. "Start" means the car is now allowed to start.

On a normal start, you depress the clutch and it starts, if it's not depressed, the switch isn't on, thus it can't start.


Now, after your mod, say you want to start the car, but the shifter ISN'T in neutral, the signal can't get to ground, thus the car can't start...exactly what you want to happen as your safeguard.


Now, with the shiter in neutral, the circuit is open, so it allows the signal to pass to ground, so the car will now be allowed to start.


If you guys can't see it now, than I give up...really.

Yep, you're right.
Ryan: do it this way. It's simple, elegant, and it works.

If you do it that way you will still have to press the clutch to start the car. The power wire that runs to the starter is broken by the starter interlock switch. If you do what is posted above, you won't be bypassing the starter interlock switch, so no power will get to the starter at all.

Funny you're right. People keep refering to there only being one but there are actually 2 switches on the clutch pedal. It's just that there's almost no information regarding both. Also everyone just refers to both of them as the clutch switch, but really, that's the most important one and the one we're working with. I means that diagram won't work, and a relay with power will need to be involved, but it's no biggie. I'll fix that up.

Ryan: try it, it works.

Poisondrop: if you're an electronics engineering student, you can't not understand how that works. Especially after ND's diagrams.

Actually, Poison may be right. I didn't realise that there are 2 clutch switches! One is just a random switch that's tied in withthe neutral switch. Those are probabaly to tell the ECU to change something when the engine is in neutral, the other is when the switch is totally depressed for starting the car. I need to see this for myself on (what's left on) on my car, but I did a search and almost no one mentions that little detail.

Here are the 2 options I've thought of so far, but no, those first attempts, although the wiring is right, won't let the car start because the Clutch Switch isn't the Safety/Interlock Switch

Nd4SpdSe wrote:Actually, Poison may be right. I didn't realise that there are 2 clutch switches! One is just a random switch that's tied in withthe neutral switch.

No, there aren't. There's one "starter/clutch interlock switch", mounted near the top of the clutch pedal assembly, and a "neutral switch" mounted on the transmission, under the right CV axle outlet. Your diagram with only the extra switch should work perfectly, no relay needed.

This one looks like a winner to me, although the "Your Switch" switch is redundant. You need only switch the one 12v wire.

One is just a random switch that's tied in withthe neutral switch. Those are probabaly to tell the ECU to change something when the engine is in neutral, the other is when the switch is totally depressed for starting the car.

The neutral switch is tied to the clutch switch because they send the same signal to the ECU, just for different reasons. But you have to realize that the neutral and clutch switches have nothing to do with starting the car. Neither does the ECU. Ryan is just using the neutral switch for some added protection from human error.

In the wiring diagram, power from the ignition switch passes through the starter interlock switch and runs to the starter directly. When you turn the key, the starter interlock switch MUST be engaged in order to complete the circuit and power the starter coil.

Inodoro Pereyra wrote:Your diagram with only the extra switch should work perfectly, no relay needed.

If this is the diagram you're talking about, I hate to quote myself, but...

PoisonDrop wrote:

Nd4SpdSe wrote:

That circuit does nothing but connect wires that are already connected...

I'm going to try and dig up an old harness I have in storage so I can test some of these. I think I have an old ECU as well, just in case. You know, with all the R&D we're doing here, you'd think we were going to market these things...

PoisonDrop wrote:

Inodoro Pereyra wrote:Your diagram with only the extra switch should work perfectly, no relay needed.

If this is the diagram you're talking about, I hate to quote myself, but...

PoisonDrop wrote:

Nd4SpdSe wrote:

That circuit does nothing but connect wires that are already connected...

I'm going to try and dig up an old harness I have in storage so I can test some of these. I think I have an old ECU as well, just in case. You know, with all the R&D we're doing here, you'd think we were going to market these things...

That's the diagram, and that was my first reaction too. But if you look carefully, when the neutral switch is closed (when the tranny is in neutral), the bypass switch is connecting the clutch switch with ground, through the closed neutral switch, therefore bypassing the clutch switch.

True, but what's the point?

Look at it this way. Both the neutral switch and the clutch switch ground a brown/yellow wire when active. These two brown/yellow wires are connected to each other, therefore both switches ground the same pin on the ECU, essentially bypassing one when the other is activated. So the switch, in this case, is completely redundant. The ECU can't tell the difference. It only cares that the gears aren't engaged, not how they got that way.

Plus, like I said, the clutch switch in that diagram has nothing to do with starting the car. It is pointless to bypass it. You must bypass the starter interlock switch, which is a totally different circuit. That is why I believe a relay is absolutely necessary, especially because of the current that the starter interlock switch handles (40A, judging by the wire gauge used).

You know this is essentially remote start without the remote.