Can the Unused Auto Start/Stop Switch Be Used for Accessories?

[krisk]

I have a job 1 GT without the Auto Start/Stop, and as a result the leftmost button on the switch panel is blank and unused. I am wondering if anyone has looked to see if the panel is wired in a way that the blank button could be used to switch on/off an aftermarket accessory? I need to add a switch for a differential cooler, but I would prefer to not add an aftermarket switch if I can just use the button that is already there.

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[R3tro GT]

There was a thread about this last Week. Do a search

 

[GhastlyTT]

The wiring is the same for those with and without start/stop labeling. Some discussion happened here https://www.mustang7g.com/forums/threads/poverty-button-replacement.162009/ but no one has attempted yet.

 

[5.0ALM]

That switch is on the LIN bus for that module, which would then communicate to the CAN bus.

 

[krisk]

There was a thread about this last Week. Do a search

My apologies for the similar thread. I did search, but apparently did not use sufficient terms to pull up the old thread.

The wiring is the same for those with and without start/stop labeling. Some discussion happened here https://www.mustang7g.com/forums/threads/poverty-button-replacement.162009/ but no one has attempted yet.

Thanks for the link. The wiring diagram is helpful. I may see if I can get it to work.

 

[krisk]

That switch is on the LIN bus for that module, which would then communicate to the CAN bus.

I am certainly no expert in automotive electronics, so while I have a vague idea of the protocols, I don't know enough about them to interpret what that means for my application. What I would hope is that the blank switch "button" would toggle a wire between 0V and 12V which I could then tap and use with a relay to control the cooler pump.

 

[roadpilot]

While I have not looked behind the switch plate, I highly doubt they included anything behind that switch.

I am certainly no expert in automotive electronics, so while I have a vague idea of the protocols, I don't know enough about them to interpret what that means for my application. What I would hope is that the blank switch "button" would toggle a wire between 0V and 12V which I could then tap and use with a relay to control the cooler pump.

What you describe would be SPST (single pole single throw) switch, which means 12V would have to flow through that switch while powering the device (or relay) it is controlling. I just don't see those thin, tiny switches being rated to do that.

I'd be willing to bet that every one of those buttons are momentarily on contact switches (rated for a few milliamps) that do nothing more than trigger a relay or similar circuit located somewhere else in the vehicle.

In order to use as a relay trigger for something like a cooler pump, they would have to send 12V to the relay at all times. Again, I just don't see those switches being rated to do that. I see them more rated/suited for electronics, not electrical. Again, momentary contact switch.

Beyond that, why would Ford spend the money to put a fully functional AS/S system or circuitry including the module, relay and wiring, in the vehicle, say, "Hey, we are going to save money during the chip crunch, so we're NOT putting AS/S into the vehicles and giving you a $50 credit", then just disable it via programming? That would make ZERO sense.

 

[Sofa King]

I'd be willing to bet that every one of those buttons are momentarily on contact switches (rated for a few milliamps) that do nothing more than trigger a relay or similar circuit located somewhere else in the vehicle.

Probably don't even trigger a relay, probably just an input to a control module that does the work...

 

[roadpilot]

Probably don't even trigger a relay, probably just an input to a control module that does the work...

Yes, a relay can be electrical or electronic.

Bottom line, that switch is not going to be carrying any kind of amperage over a few milliamps at most.

 

[krisk]

Probably don't even trigger a relay, probably just an input to a control module that does the work...

Yes, a relay can be electrical or electronic.

Bottom line, that switch is not going to be carrying any kind of amperage over a few milliamps at most.

Sounds like the best bet is just to wire a new switch. Thanks for the feedback!

 

[roadpilot]

Sounds like the best bet is just to wire a new switch. Thanks for the feedback!

Not saying it can't be used to trigger an appropriate relay that will, itself, do the job. It just won't carry the load itself.

It's been a few years, but look into latching relays and impulse relays. IIRC, an impulse relay will trigger on/off (toggle) and remain on (or off) even when the trigger is no longer providing power.

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