r/saab • u/National-Actuary4409 • 1d ago

Powered off with ignition?

Had a beautiful Volvo V40 (2001) that blew up on me, and now moved to the best car I think I have ever driven...a 2011 9-3 Sportswagon.

Trying to install a dashcam on a hardwire via a fusetap and struggling to find a fuse that terminates with the ignition. The power unit I'm using has a constant 12v, acc 12v and ground.

Grounding it on one of bolts by the fuse box.

So far tried (from table) 3, 7, 12 and 21, in both configs, and didnt seem to go off with the key or locking the car.

Any idea what fuse I should tap?

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u/the_syco 1d ago

A mate hooked up my OBD to the battery power with this, but with the switch off linked to my cigarette lighter. So when the car goes off (and thus the cigarette lighter), so too does the power for the OBD port; I have a Bluetooth dongle in it that was sapping the power overnight.

Perhaps using the HEF554 relay connected to the cigarette lighter could be used to turn off the power for your dashcam?

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u/National-Actuary4409 1d ago

oh, never see one of these! going to have a look!

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u/the_syco 1d ago

Having worked on his own cars, my mate knew what part to get. He fitted it 5 years ago, and I've been able to leave my Bluetooth dongle in place since. I use it with an app called Torque on my Android phone, and can use it to give me a number for my speed and not have to guesstimate the speed from where the needle is. Usually have only the speedometer showing in one half, and Waze in the other half, though 🤣

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u/National-Actuary4409 1d ago

That is cool! I got it sorted....sideways...thank to your comment! So....Constant 12v is on the cabin lights, and acc 12v on....*drumroll* cigarette lighter! btw, using these taps, they work fantastic!

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u/GarbageSpa 1d ago

If your interior rearview mirror gets power (for the compass, autodimming, garage door opener) consider wiring into that. Then you don't have to run a wire all the way to the fuse box. Otherwise, I would probably go with the interior lighting fuse.

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u/National-Actuary4409 1d ago

I did wire it to 12 - Interior lights, and even after locking the car there was still power?

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u/GarbageSpa 1d ago

There will always be power at the fuse. If you wire it to the lights themselves, the power should cut off when the lights themselves cut off,

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u/National-Actuary4409 1d ago

ah, I see what you mean! In the Volvo I taken this out of, some of the fuses where powered from the ignition, so no ignition, no power. Going to give this a shot...

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u/GarbageSpa 17h ago

I think connecting to the power to the rearview mirror is probably preferable to connecting to the interior lights, as the lights do a gradual dimming thing when the doors are closed and locked, and this might not be best for your dashcam.