How can you tell if your 2003 Lincoln Navigator had a factory DVD player installed if there is an aftermarket one in now?
Factory cover housing should match with the rest of the vehicle. After market are always all black.
Yes, i found the answer. Truck had an aftermarket tachometer installed. 2nd truck this tach has been on. After 320,000 mi. on this tach, something in the wiring or internals failed. Unplugged the tach, truck fired right up. Check those aftermarket accessories you installed, before finding fault with the factory stock vehicle.
Check your fuses I recently installed an aftermarket stereo and had the problem of the unit turning on and off repeatedly. The factory ground wire was to thin/weak. I grounded my new unit directly to some metal that was inside the dash where the stereo was to be mounted. It worked well and stayed on after that.