If these readings are with the car off (engine not running) then they are pretty good and indicate a good battery in a good state of charge.

If they are with the engine running, then yeah, your charging system (alternator, regulator etc.) is a little suspect. I would expect to see voltage well above 13v with a good charging system, with 13.8-14.2 being the norm.

If your charging system has failed, you would likely have an orange battery icon lighting up on the cluster but as you haven't mentioned this, I assume it's not.

Have you unlocked the diagnostics readings on the cluster BC? You can check the system voltages there too - menu #9. It reads about 0.3-0.5v low but it's a good indication of what's going on.

Good day!

Did you swap the battery? Did it actually start? The voltage at the headlights is right, but the lack of sufficient amps will also make them dim... A dead cell in the battery (or a bad connection) will give you the 12 volts, but far less amps than needed...

Do you have a known good battery you can swap in the X just to verify that is or isn't the culprit?

Cheers!!

BTW, if your only symptom is dull headlights for a few weeks (until the battery went flat/died) then your alternator is most likely ok, as a dead alternator and/or regulator would have left you stranded long ago.

Do you have halogen or xenon (HID) headlights?

I'll have a look over the wiring diagrams and see if I can identify a common earth or supply source that could be the source of your problem...

Do I need to remove the full headlight to check the lense?

That would be great! I have xenon headlights

I wasn't referring to the projector lens inside the headlight assembly - I meant the out plastic cover. The internal projector is well protected.

Ah my mistake. I'm not sure if it looks dirty as I have a mesh over the headlights. This mesh is not the cause as the lights were pretty bright until a few weeks ago but I'm not sure how I would clean them without removing it. And as both headlights went dull at the same time it tells me it could be an electrical issue?

If you measured the headlight voltages at the headlights themselves (both power and ground wires) then the ground path question isn't relevant but if you measured from the lamp power wire to somewhere on the chassis (a bolt etc.) then it's very relevant.

The left xenon headlight is connected to ground (earth, chassis, -ve, etc.) at earth junction X165.

http://i49.photobucket.com/albums/f2...psctcube0w.png

in front left wheelhouse

The right xenon headlight is connected to ground (earth, chassis, -ve, etc.) at earth junction X166 and X1106.

http://i49.photobucket.com/albums/f2...psyp5kypud.png

wheel well, front right

If you have fully adaptive xenon lighting (turn left and right as well as up and down) there is an additional ground point for both lights at X10012.

http://i49.photobucket.com/albums/f2...psgrvbyka5.png

footwell, passenger's side LH A-pillar

Check all the brown wires are secure and that the ground terminal is well connected to the bodywork. You might even want to do a resistance test from each ground junction back to the large ground terminal on the inside of the left front fender (the used for jump starting). Should be a very low resistance.

HTH...

Thanks again wpoll. I will do a resistance test and check all grounds are clean and secure.ill post results once completed.
Thanks again

Trans Fail Safe
 

I got a Trans Fail Safe while car was idling in park. Turned ignition off, car would not start. Started acting as battery was dead. Let sit for an hour, car started and drove fine for 3wks. Started car and Trans fail Safe came on again, then put car in gear and pulled off and car was sluggish. Parked car for that day and came back with lights on and would not turn over. Then battery died. Had battery tested and tested good. Recharged battery and install, Trans fail safe again. IDK what to try. Also, 4X4 light is on.