I have an 04 Acura TSX automatic. The low beams will not come on and the battery is reading at 14.1 when it is running and 12.4 when the engine is off. Already changed the Ballast and that seemed to fix the problem for two weeks. Now back to no Low beams, except some times sporadically. High beams work every time Iv checked all the fuses and the ground. Could it be the alternator?
Test the ballast first. Then check the bulbs. If they both checked out, you may have a short issue.
If the fuses and bulbs and relays are good, I would be looking at the switch itself. The alternator sounds like it's fine with your readings.
Changed the switch. Still no Low Beams
Maybe begin troubleshooting by checking to see if there's Power on Fuse 1 and Fuse 6 in the underhood fuse box when the headlights are turned on. Grab a test light, clip the alligator clip to Battery Negative, and probe the fuse test tabs. Make sure the test light lights up.
If the test light lights then the problem is between the fuse box and the headlights.
Here's the wiring ((I highlighted Red for Power and Green for Ground over the real wire colors)):
((In the 1st diagram)) If there's Power on both of those fuses then you know the controls and the integrated low beam relay is working so you can use the test light to see if there's Power on one of the wires and Ground on the other wire at the connectors to the HID units at the headlight assembly. If there is then you have to suspect a problem with the HID units (which you just replaced) or the bulbs.
If there isn't Power on both of those fuses, then ((in the 2nd diagram)) check Fuse 7 and Fuse 21 in the under-dash fuse box. If they're OK and ruling out any broken wiring or corrosion in any of the wiring connectors then you may suspect a faulty Combination Switch Control Unit (windshield wiper/washer switch).
Are these the OEM headlights or aftermarket LEDs? What ballast are you referring to?