Key Start and push button diagram

[hennessyVV]

Hey yalls,

Can someone confirm for me if I am on the right path here with my ignition wiring (turn key to start position and then press button to start vehicle. I seem to remember seeing a post or diagram someone recently posted but cannot find it for the life of me. Where does the 87 post on the 4-pin relay connect to?

I am using the Mustang Ignition switch cylinder with a scott drake harness, 4-pin relay and a start button.

So far this is what I have:

IGNITION SWITCH + RF Harness
RF harness (orange-IGN FEED) connects to the RED/GREEN wire on the ignition switch
RF harness (red- HDLT SW 1 Feed + red-IGN SW) connects to the YELLOW wire on the ignition switch
RF harness (LT blue EFI Crank + LT blue-IGN SW) connects to the RED/BLUE wire on the ignition switch
RF harness (brown- ACC Feed) connects to the post on the ignition switch

4-PIN RELAY
85-ground wire
30-12V from distribution block
86-red + green wire from start button
87-??

Start Button

Red + Green connects to 86 on the relay
Black- ground
Green (normally open) connects to 12V source

207452

[weendoggy]

Looking at your diagram/picture, 87 would be the feed to the starter solenoid. Power would travel from the key "ON" to the "start button", then push the button to power the solenoid and the connection between 30 & 87 goes to the starter solenoid. You still would need to make sure the power goes to the ignition side of your setup in crank and start mode. You wouldn't use the LT-blue wire because you're not using the keyed switch to start the engine. I think this would clear your starter issue.

207453

[hennessyVV]

Looking at your diagram/picture, 87 would be the feed to the starter solenoid. Power would travel from the key "ON" to the "start button", then push the button to power the solenoid and the connection between 30 & 87 goes to the starter solenoid. You still would need to make sure the power goes to the ignition side of your setup in crank and start mode. You wouldn't use the LT-blue wire because you're not using the keyed switch to start the engine. I think this would clear your starter issue.

207453

Hey thank you for the fast response. Just to clarify:

1. Disconnect the LT-Blue wires (Ron Francis harness) from the mustang ignition switch, '87' would go to starter solenoid.
2. Can I just connect the LT-Blue wires to '87' on the relay?

[weendoggy]

Hey thank you for the fast response. Just to clarify:

1. Disconnect the LT-Blue wires (Ron Francis harness) from the mustang ignition switch, '87' would go to starter solenoid.....Yes, 87 goes to the starter solenoid circuit on the starter or relay, whichever you're using.
2. Can I just connect the LT-Blue wires to '87' on the relay?

1. Where do they go in the harness? Starter? Fuse? If that wire in the harness goes to the starter solenoid, then yes, put it on 87.
2. ....Why?

From what you say, the LT-Blue wire is the "start" circuit on the keyed switch. That will work only if you turn the key to the "start" position. You don't need that if you intend on using the push button. Otherwise, you'd need to have the key turned to the start position and then push the starter button. You'd need two hands for that or a way of turning the key to start and pushing the button with one hand. Not sure why you'd want to do that.

[weendoggy]

Maybe this will help...
207464

[dbo_texas]

This might help: https://thefactoryfiveforum.com/showthread.php?49487-Keyed-Start-with-Push-Button

Basically you use both the key and start push-button on the coil side of the relay (trigger contacts 86-85). Both must be “closed” to close the coil trigger circuit on the relay and send +12V power (terminal 30) to the starter wire in chassis harness (on the relay output terminal 87)

The pics in the original post aren't showing up for me but I "think" this is what it showed. This is not my image - I think I screen grabbed it for the post linked above.
https://thefactoryfiveforum.com/attachment.php?attachmentid=207465&d=1734110348

[hennessyVV]

Maybe this will help...
207464

Thanks for the response. So from what I gather, I would connect the LT-Blue wire to 87 and not the red/blue wire on the key switch? Forgive me if I'm a bit slow on this.

Would something like this work:
207470


This is the diagram I was initially referring to!
https://hosting.photobucket.com/239a0216-6f9e-4cc9-a0be-2ec53fb3e15d/3ec90e06-1676-4660-89a9-00abc81e6069.png?width=960&height=720&fit=bounds

[weendoggy]

hennessyVV sent you a PM

[cv2065]

Here's an updated version of the above diagram that will go along with the push button you have from billet buttons.

https://hosting.photobucket.com/239a0216-6f9e-4cc9-a0be-2ec53fb3e15d/3ec90e06-1676-4660-89a9-00abc81e6069.png?width=960&height=720&fit=bounds (https://hosting.photobucket.com/239a0216-6f9e-4cc9-a0be-2ec53fb3e15d/3ec90e06-1676-4660-89a9-00abc81e6069.png?width=960&height=720&fit=bounds)

[weendoggy]

Would something like this work:
207470

This is the diagram I was initially referring to!
https://hosting.photobucket.com/239a0216-6f9e-4cc9-a0be-2ec53fb3e15d/3ec90e06-1676-4660-89a9-00abc81e6069.png?width=960&height=720&fit=bounds

Nice to chat about this and hope it helps. I'm really not sure what those other diagrams are intending to do, but they won't accomplish much. Maybe the person who posted can explain it to all of us.

To answer your question, yes, that would work. I've added to it here to help. Also put a simple diagram to show how to install it. The clutch saftey switch is an option, but should be put in the feed to the relay, not after on the solenoid side. It can be put on the ground side of the relay as well. You shouldn't "break" the load wire from relay to solenoid.

207533 207534

[hennessyVV]

Nice to chat about this and hope it helps. I'm really not sure what those other diagrams are intending to do, but they won't accomplish much. Maybe the person who posted can explain it to all of us.

To answer your question, yes, that would work. I've added to it here to help. Also put a simple diagram to show how to install it. The clutch saftey switch is an option, but should be put in the feed to the relay, not after on the solenoid side. It can be put on the ground side of the relay as well. You shouldn't "break" the load wire from relay to solenoid.

207533 207534

Thank you so much for taking the time and going through the harness with me! It is much appreciated!

[cv2065]

I'm really not sure what those other diagrams are intending to do, but they won't accomplish much.

My goal was to keep my start switch active in the event of a push button failure. Key differences I see is that you have the Green switching wire going from the button going to the IGN where I have it going to the Gauge feed which is ACC powered. I was trying not to clutter the IGN connector as I believe ACC is powered during IGN as well. Can you tell me why you have Terminal 30 going to both the battery connector on the switch and a 12V power block? I also fused that wire. You have terminal 87 going directly to the Solenoid where I have it routing through the switch as I wanted to make that functional, as I'm also using the Solenoid connector on the key switch.

What is dysfunctional with my diagram? Not an electrician by any means.

[weendoggy]

To each their own, but in your diagram the push button is only supplying power to the ignition side of the key switch, according to your arrow pointing to it. If you wanted the key "starter" side still able to work in a failure of the push button, you should've shown #87 going to the Solenoid terminal of the key switch. IMO, the drawing is inaccurate. By having the Green wire connecting to the ACC terminal, you have the push button "live" when in the ACC position, which if someone pushed it, the starter would spin (provided they don't have a clutch safety switch installed). Bat + power is relative, so you can have it come from a power block, direct Bat +, or any other 12v. active source. It just depends on what you want. Having a fuse for the ignition is not needed if you have a master fuse somewhere prior, imo. Again, to each their own. Also, I'm am not a proponent of sending load power (#87) through simple switches. Same as I do for a 12v. fan, heater, etc. Just not good practice. Again, the drawing you provided is just not clear for someone not familiar with circuits. If I was a newbe, I'd be connecting #87 to the IGN side of the key switch and then wonder why my starter isn't working. jmo

[cv2065]

To each their own, but in your diagram the push button is only supplying power to the ignition side of the key switch, according to your arrow pointing to it. If you wanted the key "starter" side still able to work in a failure of the push button, you should've shown #87 going to the Solenoid terminal of the key switch. IMO, the drawing is inaccurate. By having the Green wire connecting to the ACC terminal, you have the push button "live" when in the ACC position, which if someone pushed it, the starter would spin (provided they don't have a clutch safety switch installed). Bat + power is relative, so you can have it come from a power block, direct Bat +, or any other 12v. active source. It just depends on what you want. Having a fuse for the ignition is not needed if you have a master fuse somewhere prior, imo. Again, to each their own. Also, I'm am not a proponent of sending load power (#87) through simple switches. Same as I do for a 12v. fan, heater, etc. Just not good practice. Again, the drawing you provided is just not clear for someone not familiar with circuits. If I was a newbe, I'd be connecting #87 to the IGN side of the key switch and then wonder why my starter isn't working. jmo

Thanks for the feedback. I thought about the green switching wire going to the Solenoid on the switch instead of ACC and can make that change. I won't have a clutch safety switch. Fused power will continue to go to the distribution block. In terms of 87 going to the Solenoid, my thinking was that if I'm going to keep the switch live in the event of a button failure, the ignition switch is already feeding the Solenoid through the 'S' terminal, so more or less piggy backing on that from the relay? Then again, to your point, that would be 30A running through the switch which is maxed out at that amperage. So maintain the connection to the S terminal so the switch works and run the 87 terminal of the relay to the solenoid as you have laid out. That makes sense.

[weendoggy]

Thanks for the feedback. I thought about the green switching wire going to the Solenoid on the switch instead of ACC and can make that change. I won't have a clutch safety switch. Fused power will continue to go to the distribution block. In terms of 87 going to the Solenoid, my thinking was that if I'm going to keep the switch live in the event of a button failure, the ignition switch is already feeding the Solenoid through the 'S' terminal, so more or less piggy backing on that from the relay? Then again, to your point, that would be 30A running through the switch which is maxed out at that amperage. So maintain the connection to the S terminal so the switch works and run the 87 terminal of the relay to the solenoid as you have laid out. That makes sense.

First, don't make it harder than it is. Also, understand how each device works. EX: the "S" terminal on the key switch only works when you turn the key to that position. It is NOT hot (12v) all the time. So, in your diagram, the push-to-start would never work. Also, the 30A breaker should never see that load going to a simple solenoid. You'd be surprised how little the solenoid draws. As I said, the way you have your diagram shows the push-to-start just feeding the IGN side of the key switch, which would get power as soon as the key is in the ON position. It wouldn't hurt anything, just wouldn't engage the starter solenoid. Your arrow directions are also a bit misleading. I've taken your diagram and modified it to show you how you'd make it work in your setup. In this diagram, the push-to-start button would engange the starter solenoid and if it failed, you could still use the key to make it wrok. Hope this helps you out.

207554

[cv2065]

First, don't make it harder than it is. Also, understand how each device works. EX: the "S" terminal on the key switch only works when you turn the key to that position. It is NOT hot (12v) all the time. So, in your diagram, the push-to-start would never work. Also, the 30A breaker should never see that load going to a simple solenoid. You'd be surprised how little the solenoid draws. As I said, the way you have your diagram shows the push-to-start just feeding the IGN side of the key switch, which would get power as soon as the key is in the ON position. It wouldn't hurt anything, just wouldn't engage the starter solenoid. Your arrow directions are also a bit misleading. I've taken your diagram and modified it to show you how you'd make it work in your setup. In this diagram, the push-to-start button would engange the starter solenoid and if it failed, you could still use the key to make it wrok. Hope this helps you out.

207554

Thanks for the clarification. You’ve been a big help!

[D Stand]

Hello HennessyVV, noticed you are in Bothell. I am in Bothell as well with a completed MK4 without paint. Hopefully you get your wiring sorted out. Looks like you are on the top of Nike hill, I am near Shelton View Elementary.

[dbo_texas]

First, don't make it harder than it is. Also, understand how each device works. EX: the "S" terminal on the key switch only works when you turn the key to that position. It is NOT hot (12v) all the time. So, in your diagram, the push-to-start would never work. Also, the 30A breaker should never see that load going to a simple solenoid. You'd be surprised how little the solenoid draws. As I said, the way you have your diagram shows the push-to-start just feeding the IGN side of the key switch, which would get power as soon as the key is in the ON position. It wouldn't hurt anything, just wouldn't engage the starter solenoid. Your arrow directions are also a bit misleading. I've taken your diagram and modified it to show you how you'd make it work in your setup. In this diagram, the push-to-start button would engange the starter solenoid and if it failed, you could still use the key to make it wrok. Hope this helps you out.

207554

Weendoggy I have a question - with this modified diagram, wouldn't you be able to start the car without the key? If the output (87) of the push button relay is connected directly to starter solenoid as shown, won't pushing the button start the car regardless of key position? Just want to make sure I understand...if true, this would create a security risk. I'm new at electrical (and using relays) so I'm still making sure I understand all the schematics as I dive into electrical. I think your original diagram in post #10 addresses this by forcing the circuit to go through the key switch and it has to be turned to IGN position so that is in series with the push button circuit (on the relay coil trigger). Putting them in series means both have to happen in order to start.

To address cv2065's concern about push-button failure and wanting to have a key backup, couldn't you run a wire from the key switch "start/solenoid" terminal and connect it to the starter solenoid in parallel to the purple wire (pin 87 of the relay)? This would be redundant but would still give you the option to start with key (and bypass the push button).

Let me know if I have that right or if I'm just totally confused.

[dbo_texas]

This is what I mean:

https://thefactoryfiveforum.com/attachment.php?attachmentid=207672&d=1734535000

[weendoggy]

Weendoggy I have a question - with this modified diagram, wouldn't you be able to start the car without the key? If the output (87) of the push button relay is connected directly to starter solenoid as shown, won't pushing the button start the car regardless of key position? Just want to make sure I understand...if true, this would create a security risk. I'm new at electrical (and using relays) so I'm still making sure I understand all the schematics as I dive into electrical. I think your original diagram in post #10 addresses this by forcing the circuit to go through the key switch and it has to be turned to IGN position so that is in series with the push button circuit (on the relay coil trigger). Putting them in series means both have to happen in order to start.

To address cv2065's concern about push-button failure and wanting to have a key backup, couldn't you run a wire from the key switch "start/solenoid" terminal and connect it to the starter solenoid in parallel to the purple wire (pin 87 of the relay)? This would be redundant but would still give you the option to start with key (and bypass the push button).

Let me know if I have that right or if I'm just totally confused.

Simple answer, NO, it won't start, UNLESS the operator has the key in and turned to the ON position. The starter could spin, but only if the feed to the push-to-start button has power, and there isn't a clutch safety switched wired in, requiring the pedal (or other mechanism) to allow current to travel to #86. It really depends on how the person is supplying 12v signal to the push-to-start button. So, lets say it's wired 12v hot all the time, the push-to-start would work, engaging the starter (in gear or not), but the car wouldn't start because the key isn't in the switch and turned to ON. If it was, it would start. With the key out, there's no power going to the IGN side of the key switch, thus meaning it's dead. If I was to wire this setup, I'd make sure my push-to-start button would NOT get 12v until I had the key on.

As for your post about the switch SOL powering the starter as well, that's exactly what is going on here, and you'll notice I have 12v coming to the push-to-start via the IGN terminal. However, hennessyVV isn't doing that. Yes, that's redundant but it'd work.

edit: Also in you purple dash wire, it would by-pass the safety switch if one was being used.