Push Button Start System

ctuinstra

Well-Known Member
#1
I'm working on incorporating a push button start system in to the car. We talked briefly about this in the VATS thread. While I've just started, I figured why not post about it along the way for others.

It seemed, at first, to be quite simple, however, there had to be something to stop it from being easy. First of all, I'm fortunate enough to have my VATS (see the VATS thread for more info by clicking here) disabled already. If you don't, you may be able to by sending it off to ZZP or having someone local with HP Tuners disable it. The expensive route is to purchase HP Tuners and do it yourself, the pro here is that you can use it to tune your car also if you are so inclined.

This is the unit I purchased online for $70:

https://www.amazon.com/gp/product/B07FSTFDY2/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

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I chose this unit because it's a stripped down version of some of the others. There are many features included in the others that we simply don't need. This one still has door lock, etc. but you just aren't going to find one that basic. The price was at a good point for attempting. If I feel that it's inferior, I will probably upgrade. After receiving the unit, I cannot complain about it at all. Well, actually the only complaint is the poor directions derived from the language translation. The instructions are barely enough to get started, hence why I'm doing this write up. I really like the button itself, it has a really cool blue halo glow to it that changes with the mode that it's in.

Hopefully I can muddle my way through it and get it to work and make it a lot easier on anyone else wanting to tackle the project.

Continued...
 
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ctuinstra

Well-Known Member
#2
The wiring for the original key switch I found to be quite different than expected. This is the beginning of the difficulties, although it should still be very doable. The first thing I noticed is that the Cobalt has a 5V logic line for the start command and not just a simple 12V switch. I assume this is to prevent others from hot-wiring the car and stealing it.

Sorry the image is so poor, it's the only one I could find and I had to do a screen capture of it. If you notice on the far left side, the BCM has a 5V reference line that runs through one leg of the ignition switch. From there it goes to the switch where there is a 1.3K ohm resistor ( I actually measured 1.8K on mine) for the start circuit. While the car is in the Run condition, the 5V reference is fed back to the BCM until it's turned off. This is by far going to be the fun part. The rest of the circuits for the ACC and Run are simple 12V switched and the unit will work well with those.

Ign Switch.JPG



This is the Theft Resistor and what I measured.

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Since the push button start unit is designed to work universally, it just switches 12V to all of the outputs. As stated earlier, we are dealing with the 5V logic line. So I started to modify my circuit board in an attempt to inject the 5V to the relays instead of the 12V and include a spare 1.8K resistor I had. The hope was to make this still a contained unit and simplify things. Unfortunately I didn't fully realize the diagram of the relays until I was quite ways in to the modification. You can see them here, but there are four relays in the middle and the pin outs are really weird! In the process of using the reflow to remove one of the relays, I apparently destroyed it in the process. So I now I have a replacement on its way from Japan (read major hold up to this project).


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I now fully realize there is no work around using the circuit board and I will have to move on to plan B. That will be two external relays just for the Start circuit.


https://www.amazon.com/gp/product/B0721M34CM/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

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As soon as I get the replacement relay and the two additional relays, I will continue forward. I don't want to scare anyone away from this and I'm afraid I probably already have. My hope is to make it as simple as possible in the end. I will simplify everything with good directions and diagrams once it's up and running well.
 
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Nilbog

Well-Known Member
#4
Apologize for my ignorance (and the drinks i've just had :) )but are we making this more difficult than it needs to be? Is the goblin application different than if this was installed on say a stock cobalt (for instance)? Or are all these modifications you speak of required for any car it is installed on?
I think i responded to the VATs thread when this was brought up.... i assumed (likely poorly) that this would be plug in play
 

ctuinstra

Well-Known Member
#5
Apologize for my ignorance (and the drinks i've just had :) )but are we making this more difficult than it needs to be? Is the goblin application different than if this was installed on say a stock cobalt (for instance)? Or are all these modifications you speak of required for any car it is installed on?
I think i responded to the VATs thread when this was brought up.... i assumed (likely poorly) that this would be plug in play

Without knowing the exact inner workings of the BCM and the security circuits, I don't know how it could be made any easier. Because of the Theft Resistor, if you were to bypass it or ignore it and just jump start the engine, I don't think it will start or you would possibly be missing many of the accessory circuits for other things to function. At its core, I'm just trying to replace the actual key switch exactly as it is in the car. You may see in the diagram, there are actually three complete and isolated switches in the key switch unit.
 

ctuinstra

Well-Known Member
#7
Is there a chance that the 5V and the resistor are only used for the chip in the key?
There is a separate ring (the black plastic unit) that reads the key. This is part of the VATS system. I have that currently unplugged and the car starts fine. This was the point of the VATS thread, to prove that the VATS was actually disabled. I'm quite certain the 5V logic line will have to be functioning in order for the car to start. However, I could remove that pin from the switch to see if that is the case. If it were to start without it, that would make things a lot easier! But I just don't really think it will because there is nothing else wired to the Start position of the key switch, so there is nothing else to tell the car to start. And the resistor is not really an issue, just the signal line instead of a simple 12V engagement.
 
#8
We'd typically run keyless ignitions on our race bikes, (one less thing to forget or break). On Kawasakis we had to wire in a 100 ohm resistor in line on the data line. But it was a 12v source.

Thanks for posting your findings. Hope you're able to get it to work as I was planning on using a push button keyless starter as well.
 

ctuinstra

Well-Known Member
#9
Working on it a bit more today while I wait for the replacement relay.

I changed out the very heavy gauge wires from the main plug to a much more manageable 20ga. I just couldn't stand the very heavy 12ga wires that are going to have to be connected to the car's 20ga and then try to wrap them up neatly. This also gave me the opportunity to add additional 12V and ground wires to power the relay board (not seen here).

DSCN0072.JPG




From there, I had to modify the relay board just slightly. Quite frankly, it didn't have to be modified and the same effect could be had by just trying a couple of wires together, but injecting the resistor into the circuit is where the modification really helped.

I tied the COM of the relay together and the output has to be tied together. The only reason for the relay board is the need for two different paths of the signal; one path (relay) is for the RUN command, and the other path (relay) is for the START command (with resistor)

DSCN0075.JPG




This relay board is to replace this part of the key switch.
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ctuinstra

Well-Known Member
#10
Got the replacement relay today. Soldered it in place and did a mock-up on the bench with the external relays. So far, so good! The actual start system seems to work as expected. Now I have to connect it to the car and hope there are no whammies! I'll work on that tomorrow, tonight I enjoy the snow.
 

ctuinstra

Well-Known Member
#11
Proof of concept complete!

We temporarily wired it up to the car to test it and it worked the first try. You will see in this video Kaleb "unlocking the doors" or otherwise disarming it, then after pushing in the brake and clutch pedal he then presses the button to start the car. One more press to shut it off. And then he "locks the doors" to prevent someone from attempting to start it while you in the vicinity of the vehicle.

If you don't press the Brake, you can cycle through the ACC and Run and back off.

Now we are going to work on a mounting design.

 

ctuinstra

Well-Known Member
#15
Nice job. Does the fob have to be in range for subsequent starts after you disarm it?
That's my understanding but I haven't tested it yet. I know the system will "sleep" after a while and cannot be woke up without the fob. That was the purpose behind this mod. However ther are other systems out there that are just stand alone push to start without any fobs if one wanted one.