Tonight I installed a new car stereo (no extras) into a friend of mine's 2008 Ford F150. Using a voltage tester, as well as wiring information from the internet, we went ahead and wired everything up, and everything worked. Now he says that the stereo cuts off when the car is moving, and begins working again when he comes to a stop. The only explanation I can think for this is a grounding failure, but all of the connections seem ok. I did not ground the ground wire to the chassis, but rather to a wire which I believed to be the ground due to tests with the tester. Any help appreciated. Thanks.