Where to tap for dimming on '15

[zanethan]

I'm pulling my nonexistent hair out on this one. There is no switched 12v source in my car. I have checked the headlight fuses, fog light fuses, and the auto dimming mirror fuses none of them are switched via the headlights. Does anyone know where to tap a fuse for a switched circuit??!! And before everyone links to the radar detector and auto dimming mirror discussions I have read them 5 times today but they do not apply to my car for whatever reason.

 

[zanethan]

Alright so after much frustration and a few choice words I just tapped the headlight wire itself. I'm convinced my car doesn't have a switched fuse circuit at the fuse

 

[neeqness]

Alright so after much frustration and a few choice words I just tapped the headlight wire itself. I'm convinced my car doesn't have a switched fuse circuit at the fuse

Haven't used a headlight dimmer before but my best guess (if I couldn't read the manual) would be the headlight fuse to switch it on and battery for power.

 

[zanethan]

Haven't used a headlight dimmer before but my best guess (if I couldn't read the manual) would be the headlight fuse to switch it on and battery for power.

Nope the headlight fuse is a constant 12v source on our cars. Trust me I read my manual for 3 hours trying to find a headlight switched fuse.

 

[neeqness]

Nope the headlight fuse is a constant 12v source on our cars. Trust me I read my manual for 3 hours trying to find a headlight switched fuse.

Even when the lights are off?

 

[zanethan]

Yep. It baffled me as well. If you don't believe me go check on your car. Engine fuse box fuses 23 and 25.

My guess is that it has to do with how the auto light function is wired.

 

[thePete]

Most stuff on Fords is switched ground, so many of the fuses stay hot constant, but get shut down after a few minutes by the BCM.

 

[neeqness]

Yep. It baffled me as well. If you don't believe me go check on your car. Engine fuse box fuses 23 and 25.

My guess is that it has to do with how the auto light function is wired.

It's not that I don't believe you. I was just confirming, but it makes sense now. The fuse supplies power to the switch so it has to be constant. I was thinking that the lights lose power with the engine but this is not entirely true because they can be turned on when the engine is not running.

So you'd probably have to tap into the line after the switch.

 

[zanethan]

It's not that I don't believe you. I was just confirming, but it makes sense now. The fuse supplies power to the switch so it has to be constant. I was thinking that the lights lose power with the engine but this is not entirely true because they can be turned on when the engine is not running.

So you'd probably have to tap into the line after the switch.

If I hadn't been checking it myself I wouldn't have believed it haha. But yes I ended up having to tap the actual wire after the switch.

 

[XanRules]

If I hadn't been checking it myself I wouldn't have believed it haha. But yes I ended up having to tap the actual wire after the switch.

Sorry for the Necro-Bump, but - were you able to find a dimmable circuit? I am considering purchasing a boost gauge that supports dimming and I would love to be able to actually dim the damn thing.

 

[zanethan]

Sorry for the Necro-Bump, but - were you able to find a dimmable circuit? I am considering purchasing a boost gauge that supports dimming and I would love to be able to actually dim the damn thing.

Yes but you will have to actually tap the wire running to the light and depending on what voltage your gauge uses as a reference it might not work out.

You may also "lose"the auto on/off headlight feature. As I did.

This is just my finding so if anyone more experienced with the headlight wiring knows something else please correct me. That being said it doesn't appear that there is a constant voltage going to the headlights even when on. So if your gauge needs a specific voltage to dim it may drop below that voltage causing it to brighten.

Edit the best way to dim reliably would likely be to wire the dim function on a switch. Then just flip the switch when you want it dimmed.

 

[Ecmdrw5]

I’m in the process of doing the same thing and will reply here for anyone searching in the future. I’m going with the fog light fuses. Those are the only fuses I’ve found that are only hot when the headlights are on. Only bad thing is you have to always use fog lights or the dim feature doesn’t work.


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[HardBoiledEgg]

ITS THE FACT THAT THE CAR HAS GERMAN ORIGINS

IVE DUG AND DUG AND DUG. EVERYTHING IS GROUND SWITCHED. I EVEN TRIED THE START/STOP SWITCH