Wiring for devices running only when engine is running.

[wintoon]

Hello,

I would like to wire up a device that can only run when the engine is running. Is there a terminal somewhere that is HOT only when the engine is running? Can I wire a relay there (very little power) and use that to wire from the battery to my device?

Thanks!
Sam.

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[N9WXU]

You might consider using a voltage controlled switch such as this: http://www.aprsworld.com/apo3/
With the thresholds set correctly, it will be active while the engine is running and inactive 10 minutes after the engine stops. The 10 minutes should cover the autostart/stop feature. The voltage threshold and the delay can be set with dip switches.

 

[wintoon]

Thanks! That's a great idea.

 

[jasonkosi]

You might consider using a voltage controlled switch such as this: http://www.aprsworld.com/apo3/
With the thresholds set correctly, it will be active while the engine is running and inactive 10 minutes after the engine stops. The 10 minutes should cover the autostart/stop feature. The voltage threshold and the delay can be set with dip switches.

I would avoid using a voltage switch like this. Modern cars voltage fluctuates a lot when driving, in my Bronco it’s anywhere from 12.7 to 15.1, any higher than 13 and that switch will turn off, along with any accessories connected to it. OP should instead use a fuse tap

 

[wintoon]

A fuse tap in the engine compartment would always be on correct? All fuses are always hot I believe?

Also, in general, if your alternator is working correctly you should have a pretty steady voltage coming from your engine I believe. There's always a difference between battery voltage and alternator voltage.

The switch will turn OFF when the voltage is lower than the set voltage. I believe if its set to 13 it should work nicely.

 

[jasonkosi]

A fuse tap in the engine compartment would always be on correct? All fuses are always hot I believe?

Also, in general, if your alternator is working correctly you should have a pretty steady voltage coming from your engine I believe. There's always a difference between battery voltage and alternator voltage.

The switch will turn OFF when the voltage is lower than the set voltage. I believe if its set to 13 it should work nicely.

Check the owners manual for what circuits the fuses are for. You will need to test them to know which are always hot.

 

[Bschurr]

Hello,

I would like to wire up a device that can only run when the engine is running. Is there a terminal somewhere that is HOT only when the engine is running? Can I wire a relay there (very little power) and use that to wire from the battery to my device?

Thanks!
Sam.

Fuse #35 under the dash is unused and it is switched power (only on when the vehicle power is on). Use a fuse tap and you are all set.

 

[wintoon]

Fuse #35 under the dash is unused and it is switched power (only on when the vehicle power is on). Use a fuse tap and you are all set.

Thanks. Do you happen to know if there are any switched power fuses in the engine bay?

 

[BroncoSarge]

 

[Donkeygyrl]

I used the swaybar disconnect on mine ,I have a base .

 

[EveryDayBronco]

Hello,

I would like to wire up a device that can only run when the engine is running. Is there a terminal somewhere that is HOT only when the engine is running? Can I wire a relay there (very little power) and use that to wire from the battery to my device?

Thanks!
Sam.

Yes you can.

Power for the relay can come from anything but if it was me I'd tap into the power for the 12v lighter socket.

I'm assuming you did't select the aux switches when you ordered??

 

[wintoon]

Not an option here. It was either the "nice" OBX or the "rugged" BL. I went with nice because I don't do much off-roading.

 

[UtahBrandon]

Thanks. Do you happen to know if there are any switched power fuses in the engine bay?

I tapped into #22 - the 360 camera for my backlights. Only hot when the key is on.

 

[wintoon]

Thanks!

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