Wiring a push button start

[rfstang]

Good afternoon everyone, so I want to add a push button start along with a on/off switch to eliminate the key completely, something similar like the boss 302s or watson racing prepped cars, I've been looking for a write up even the button itself with no success.. Id mostly like to know into what wires I should tap in. So if anyone has done it and happen to have a wire diagram it would be great if you could chime in! Thanks!

 

[Bill Pemberton]

Ok, could be a long shot, as I have heard Texas is a big State, but here goes ............" How far are you from Princeton, Texas?"

The reason I ask is that is where Vorshlag is located , they are very well versed in Modifying Mustangs , and they are also a site sponsor. Even if they are not close to you , you might give them a ring, as I had a good conversation with their Chief Engineer and he gave me some advice on some suspension ideas.

Good luck.

 

[Swiss Boss]

Pretty easy
Here's a link to all schematic : http://iihs.net/fsm/?d=499
Here's the schematic of the starting key


The way I did it on my car :
- Locate the connector on the key switch
- Take the Blue-Red wire and connect it to a master switch
- On the output of the master switch, connect the Blue-Grey wire ( key in ignition), Grey-Violet wire (power CC) and an extra wire to a push button. I didn't connect the Violet-Green wire (power AA) and lost the wipers
- From the output of the push button, connect the Blue-White wire (start signal)

You'll still have to put the key in the ignition because of the anti-theft system

To start the car :
- Flip up the master switch. That will power up the car like you turned the key all the way just before the cranking
- Press the push button to start cranking. You can release the push button as soon as the car start cranking.
- Flip down the master switch to kill the car.

Good luck

 

[rfstang]

Just what I needed, thanks for the info man, BTW what kind/brand of button did you use?

Pretty easy
Here's a link to all schematic : http://iihs.net/fsm/?d=499
Here's the schematic of the starting key
View attachment 17396

The way I did it on my car :
- Locate the connector on the key switch
- Take the Blue-Red wire and connect it to a master switch
- On the output of the master switch, connect the Blue-Grey wire ( key in ignition), Grey-Violet wire (power CC) and an extra wire to a push button. I didn't connect the Violet-Green wire (power AA) and lost the wipers
- From the output of the push button, connect the Blue-White wire (start signal)

You'll still have to put the key in the ignition because of the anti-theft system

To start the car :
- Flip up the master switch. That will power up the car like you turned the key all the way just before the cranking
- Press the push button to start cranking. You can release the push button as soon as the car start cranking.
- Flip down the master switch to kill the car.

Good luck

 

[Swiss Boss]

Just what I needed, thanks for the info man, BTW what kind/brand of button did you use?

I'm just using toggle switches. Car is gutted so I don't have the radio anymore.

 

[rfstang]

Ok, so after much thought im tackling this job finally tomorrow Swiss Boss and company, please hear my approach on the job to see if it makes sense to you guys:
First thing is cutting the key away from the fob and put it on the ignition always on the on position, this will serve 2 purposes, "remove" the steering lock which is a rule on my class and to hide fob next to the PADS unit in the ignition switch, this way the fob would not be on the way of my knee and will look like a true push start.
Next I would tap the master switch between the blue-red wire and then tap the ignition button into the blue-white wire which to my point of view simplifies the installation a lot. What do you guys think?

Pretty easy
Here's a link to all schematic : http://iihs.net/fsm/?d=499
Here's the schematic of the starting key
View attachment 17396

The way I did it on my car :
- Locate the connector on the key switch
- Take the Blue-Red wire and connect it to a master switch
- On the output of the master switch, connect the Blue-Grey wire ( key in ignition), Grey-Violet wire (power CC) and an extra wire to a push button. I didn't connect the Violet-Green wire (power AA) and lost the wipers
- From the output of the push button, connect the Blue-White wire (start signal)

You'll still have to put the key in the ignition because of the anti-theft system

To start the car :
- Flip up the master switch. That will power up the car like you turned the key all the way just before the cranking
- Press the push button to start cranking. You can release the push button as soon as the car start cranking.
- Flip down the master switch to kill the car.

Good luck

 

[Dave_W]

Looking at the schematic, the main key switch looks like it actually sweeps 2 contacts.
powered at ACC: VT-GN (& off)
powered at RUN: VT-GN & GY-VT
powered at START: GY-VT & BU-WH
The thing to note is that in the START position, the ACC (VT-GN) wire is not powered.

To wire this as a master switch and start button, ideally you'd cut the power to the VT-GN wire on the output of the master switch when you push the start button. You can do this by adding a Single-Pole, Single-Throw, Normally-Closed (SPST-NC) relay to the system.

A quick search found this as a solid-state relay: https://www.newark.com/sensata-crydom/dc60s3-b/solid-state-relay-3a-3-5-32vdc/dp/37M2361
and this as an automotive mechanical relay (much cheaper, has both NO and NC outs):

https://www.newark.com/potter-brumfield-te-connectivity/1432869-1/automotive-relay-spdt-12vdc-40a/dp/21M4883

Just make sure whatever you use has an NC output; most have an NO output.

From the contact on the start switch that the BU-WH wire is connected, connect a second wire that goes to the input/control side of the relay. On the other input/control connection of the relay, add a wire that goes to ground. Then take the VT-GN wire, and instead of wiring it directly to the master switch, connect it to the output/load side of the relay. Then wire the other output/load contact to the master switch. Since the relay is NC, it will allow power to pass from the master switch to the VT-GN wire, unless the start button is pushed (which causes the relay to open and de-energize the VT-GN wire).

Good luck, and don't let the smoke out of the wires!

 

[Dave_W]

Next I would tap the master switch between the blue-red wire and then tap the ignition button into the blue-white wire which to my point of view simplifies the installation a lot. What do you guys think?

Okay, cutting the BU-RD and putting the master switch in line seems like it would work. I'd still try to do the extra work to de-energize VT-GN on start. Cut the VT-GN and wire the ends to the load/output side of the relay. Cut the BU-WH wire and connect your start button to the cut ends. Then, add another wire from the "downstream" side of the start switch to one of the input/control contacts on the relay, and connect the other input/control contact to ground.

You can do the math for the relay wire size; for the mechanical relay I linked to, it has 90 ohm coil resistance, so 22AWG would be okay if kept under 6ft.

 

[302BOB]

Is this push start conversion possible for a Boss with a black key and red track key activated???...just curiuos..not going there anytyme soon...............

 

[Dave_W]

You would still have to put each key in (or near?) the ignition switch so the Passive Anti-Theft System (PATS) could detect which key it was. There's a PATS transceiver module in the steering column with a ring "antenna" around the ignition switch, and that sends a signal to a transponder in the key head, which returns a signal, and the PATS transceiver reads the signal returned. Something (or exactly?) like an RFID chip in the key. The ECU talks to the PATS transceiver, and determines if the key is allowed to start the car, and if it's a MyKey or a TracKey.

 

[302BOB]

Personally, because I'm old school, I like turning a key to start my vehicle..Boss, truck, whatever...Hon's Juke is push start and I've been thru the problems when the battery goes in the fob when you try to start it.....The Boss will stay key start on my watch..................

 

[302 Hi Pro]

Would it be easier just to buy and install a Push Botton accessory kit?

 

[rfstang]

Thanks for the input Dave, your're right about that.. so for the circuit to work the way you mention it would be easier then to tap the push start button in the grey-violet circuit in normally closed pole and tap in the NO side into the Blue-white pole. It makes more sense that way dont you think?

Okay, cutting the BU-RD and putting the master switch in line seems like it would work. I'd still try to do the extra work to de-energize VT-GN on start. Cut the VT-GN and wire the ends to the load/output side of the relay. Cut the BU-WH wire and connect your start button to the cut ends. Then, add another wire from the "downstream" side of the start switch to one of the input/control contacts on the relay, and connect the other input/control contact to ground.

You can do the math for the relay wire size; for the mechanical relay I linked to, it has 90 ohm coil resistance, so 22AWG would be okay if kept under 6ft.

 

[Dave_W]

tap the push start button in the grey-violet circuit in normally closed pole and tap in the NO side into the Blue-white pole. It makes more sense that way dont you think?

I suppose that works as well. Six of one, half-dozen of the other.

 

[302FAM]

rfstang, did you ever get to doing this, I'm thinking of the same thing.