Hi all, long time forum viewer, first time poster. I am wondering if anyone knows how to make the cigarette lighter power stay on even when the car is turned off in a 2003 C240. I have seen some forum posts regarding this in the E-class, but I am not sure if the idea is the same in my car. Can anyone point me to some documentation or have knowledge of this?

Thanks in advance
-oriz

Cigarette lighter should be on all the time.

It's not. When I take out the keys, the power shuts off.

OK - Yours is different to mine. Mine is like an Audi. SA assembly

Then take constant power from the fuse box in the side of the dash.

So it's not possible to make the cigarette lighter stay on?

Why are trying to do this? If you just want a constant 12v even if the car is off your radio has a constant 12v you can tap into.

I'm trying to charge a cell phone with the car off and not have to splice any wires if I can get away with it.

You have a choice - Take it from the fuse box. Rewire your cig lighter to a 20amp permanently on tap in the fuse box.

Stay away from taps that go to sleep with the CANBUS like the radio.

What's involved in rewiring it to the 20A fuse? Just a matter of moving a couple wires or is there soldering and stuff involved? I'm totally new to this and haven't taken a look at the fuse box yet.

As cars vary you need to take a meter & find a tap in the fusebox that has a wire going to it as fat as the one going to the cig lighter & make sure it does not go to sleep with the CANBUS. Then run a new wire from there to the cig lighter. This requires some careful stripping of the dash & console to feed a new wire.

If your car was prewired for a cell phone then the wiring will be there already at the side of the console. Only Benz can tell you from your VIN whether the car is prewired.