[adjulbic]

Hello All;

Just installed a single din, flip screen car deck in my 2008 BMW 323i (Pics coming soon!). Everything works flawlessly! Very happy with the install. (Thanks to Izzyswift, mosx, bmw325i and jjmandy on this forum for all their help!).

One remaining problem remains....

Where can I tie my red accessory wire into?!

There must be a fuse I can tap into that delivers 12V only when I put the key in and zero when I take the key out (maybe?). The issue is that my deck is constantly powered. So, I have to turn it off every time, otherwise it will deplete my battery.

Any ideas? I bought a fusetap and right now have it in the Home Link (It's 12V constant; key in or out), but that didn't do the trick.

Any help would be great!

Thanks all!

[bmw325i]

I'm using homelink as the remote wire for my amp and many others use it for radar detectors. There might be more than one fuse. Also I think the cigarette lighter is switched try that one.

[adjulbic]

Hey BMW325i;

Thanks for the response. Now when you saw switched you mean that 12V is active when you put the key in, and inactive when you take it out right?

Also, stupid question, which fuse is for the cigarette lighter? what does it look like? The image attached is from another thread...

THanks!

[bmw325i]

Yes that is what I meant by switched, and it's number 30 on that diagram. If that doesn't work try a few different ones that you think will work.

[adjulbic]

Thanks!

Can you suggest any others I can try? I tried a few but no luck. Also, the the cigarette lighter, it shows a draw of 20amps...that's a lot.

Do you think the BMW dealership would tell me?

Thanks!

[superjay]

you can use the lighter or fuel pump. Use a relay, either way you go

[adjulbic]

Hey Superjay! Thanks for the response. Relay? What do you mean? I can't just use a fuse tap?

[bmw325i]

I might be wrong here but I don't think you would need a relay since the head unit draws power from the constant 12 volt wire and only switches on and off with the switched 12 volt.

[adjulbic]

Hey Guys;

I'm so confused lol. Thanks for the responses though. Can you elaborate BMW325i? What do I need to get? Can you show me a screen shot?

Thanks!

[superjay]

Originally Posted by adjulbic

Hey Superjay! Thanks for the response. Relay? What do you mean? I can't just use a fuse tap?

you do NOT want to share current draw with another circuit. Using a relay will take a signal from whatever circuit you choose to tap to trigger the relay, then take current from the battery.

If you don't know how to use a relay go to www.the12volt.com and look at the diagrams there.

[superjay]

Originally Posted by bmw325i

I might be wrong here but I don't think you would need a relay since the head unit draws power from the constant 12 volt wire and only switches on and off with the switched 12 volt.

Depending on the brand of radio various amounts of current may be drawn from the constant and accessory lines. Older Clarion radios would get 70% of their current from accessory. 5-10 year old Pioneer needed so little current from accessory that they put a resistor in-line to bring voltage to 6VDC.

I ALWAYS use a relay when tapping another circuit in a car. Why? Because the harness, and fuse, were designed for THAT CIRCUIT, and its specific current needs. Adding additional current draws to a circuit can lead to problems, especially in cars like ours, where draw is monitored.

Lighter, or 12v outlet, circuit are probably the only places I might skip the relay, since they are designed for variable current draws.

[adjulbic]

Hey Superjay!

As always, thanks again for sharing your knowledge.

This is getting way to technical for me. Can I use a fuse tap and put it on the lighter cirguit?

What about the fuse? Should I set it 5 amps or 20 ? If i set it at 5, it'll probably go every once in a while. However, at 20, wouldn't the radio bust?

Thanks!

[superjay]

If you must use a fuse tap (I hate them. I've had problems with them over the years) then use a 10A fuse from the unfused side of the circuit. This will parallel your radio accessory to the existing circuit.

Remember to secure your wiring well, so that you don't have wires moving during normal operation.

Also, use 3M electrical tape or heat shrink to protect exposed metal in the connections.