Originally Posted by KeithLuneau
Looking into the connector with the wire going away from you, and with the wide part on the bottom, the pins are 1-2-3-4-5 left to right, and the outer shell isn't connected to anything! The last pin on the right should be ground, you can check that one without opening the charger up. It should trace through to the cigarette lighter plug, on one of the two metal tabs on the side. Only one is connected though, the other is just there as a spring to hold it tight I guess.
There should be that one ground pin, then one other pin will have 5V one it, it should be either pin 1 on the left, or pin 4 next to the ground pin. The other pins are not connected so you can't short them. Just be careful not to short pins 4 and 5 if those are in fact the two "live" pins. There's no telling what will blow...
I would check between pins one and 5 and see if it has 5V first, if not, carefully try pins 4 and 5!
I'll place my bet on pin #4 having the +5V from the HD car charger. Since pin #1 is standard +5V and pin#5 is standard ground, those would be used by standard PC and charger USB plugs to normally charge the camera, with the camera's additional circuitry to permit charging AND going into video recording mode being reserved for pin #4. The camera's circuit board picture shows that all 5 pins are soldered to active circuit traces, so all 5 must be used for something. Since Pin #4 is either standard open or standard ground, a normal USB charger plug would not likely do anything even if pin #4 were grounded. But if +5V were there, as it would be only from the car charger, with appropriate circuitry in the camera this would be the trigger to both charge and allow the camera to record. I don't see any other possible way for everything to work the way it does.
<EDIT> sheesh... you guys should be sound asleep by now! You proved my hunch right before I finished the picture and got it posted! <EDIT>