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!!

__________________
2001 E53 X5 4.4i (03-07-2001 build date) White exterior / hellbeige interior (6MT swap vehicle - Manny)
2002 E53 X5 4.6is (12-20-2001 build date) Imola Red exterior / M-texture interior (Red)
2003 E53 X5 4.4i (06-26-2003 build date) Silver exterior / Black interior (Silvester II)
2008 Mini Cooper S ragtop (04-17-2008 build date) Dark Silver exterior / Gray interior ( Topless)
BMWCCA member (#4745)