I am hooking up an aux iphone cable so that it will charge as well as play my tunes. I want to hook the power supply to the wires going to the cigarette lighter, but there are four wires. Anyone know which colors are ground and power?

 

Forgot to mention its a 2007 E350

 

Use Volt meter cheap at Radio shack read ground first w/meter on ohms if it shows resistance that is ground turn key on read other wires with black probe on the body metal ( the ground ) and meter on volts when you find 12 volts you have your 12 v feed and use the body ground
good luck

 

Thanks, I'll give it a try