Cigarette lighter

[BMWVW]

I just bought myself an iPod (which I am loving and a car charger. I have noticed that the cigarette lighter maintains power even after the car is shut off. Is there a way to make it switch off with the car that anyone knows of?

Cheers,
Paul.

[John Firestone]

You could move the cigarette lighter to a switched power circuit. Few, however, are wired and fused for 30A, like, I believe, the lighter is. You would probably want to get rid of the lighter glow plug and replace it with the plastic fill plug from the non-smoker package.

[BMWVW]

Thanks for the tip. I don't know that I want to change the stock fitting, so I was thinking of wiring an auxillary cigarette socket instead. Can anyone recommend a switched circuit in the interior of the car that I could potentially add the socket to in parallel?

Cheers,
Paul.

[John Firestone]

There are five possible fused circuits you could tie into that will give you power with the ignition in the radio/accessory position:

• F42 -- has the airbag: risky
• F43 -- only 5A: may be too whimpy
  
• F44 -- 15A circuit that supplies the radio among other things: perhaps your best bet if you don't have a high-power sound system on this circuit
  
• F45 -- 7.5A, but has the EWS on it: if you blow this fuse you can't start the car
  
• F46 -- 15A, but powers the instrument cluster and cruise control

I would guess F44 with VI/SW (violet/black) wires is your best bet. However, someone will likely blow this fuse if they accidently plug in and press a cigarette lighter into your second socket.

[aceyx]

find the purple wire with the white stripe; it's a switched power line.

use any ground (THIN brown) wire.

[John Firestone]

I believe that's F43 with a 5A fuse. If I can believe the ETM I am looking at, you should be able to double that fuse to 10A as the smallest wire on that circuit is 0.5 mm^2. Good call.

You'll still blow the fuse if you plug in a cigarette lighter.

I would bolt another (preferably brown) ground wire to a chassis ground point rather than tap into an existing one.

[BMWVW]

Thank you both. I think I have enough to investigate (and hopefully keep me out of trouble ). I think I will check the power requirements for the head unit and if it is low enough to safely add another piece of equipment, use that circuit.

Cheers,
Paul.

[John Firestone]

Either circuit, off F43 or F44, should be fine for your iPod. I was just thinking ahead. Someday, you may be tempted to plug in something into your second socket with a greater draw. I am now not sure which would be the better choice.

[Tyler]

Once the alarm is engaged if you have one it cuts the power to the whole car. This is on a factory Bmw alarm not aftermarket.