It sounds like that schematic is not what you got. I would imagine that your car has a close variant though. The grommet is where the wire runs through the firewall into the engine compartment. The connector can be anywhere from there the where the wire splits off the go to both head lights. If this is indeed indicative of your wiring and you have determined that the lamps are not actually failing, you might try toggling the dimmer switch rapidly when this happen to see if the lights come back on indicating that the problem is in the switch or opening the hood and basically just shaking the wiring looms in the engine compartment to see if the lights come back on pointing to a bad connection there somewhere. I think it is unlikely that you would have simultaneous lamp failure. It is far more likely that you have a bad switch. Again, if your wiring is similar to this.