Before bringing my 1997 XK8 to Canada from Florida I had the local dealer program in the daylight running lights. They left it with the parking lights, rear and side lights and the low beam headlights on at all times. Now the low beam lights are burning out every 10 hours or so of running. At first I thought it was old age but not when it repeated.
Has anybody any idea why. All I can think of is daytime heat. Are there any heat resistant bulbs?

Jack

 

What is your voltage reading with the engine running?

 

What he said. Maybe two readings ... idle and, just to pick something, 2500 RPM

 

The guage on the dash reads just over 12V and is steady. I guess it would miss a surge.
Jack

 

IMO, the gauge would be able to display a surge or transient large enough to fry headlight bulbs. Also, come to think, if that were the problem other bulbs should then be going south too.

Anything unusual about the source for the headlamp bulbs you're using?

 

Ideally the DRLs using the headlamps should run at a lower voltage to save wear on them, but using the programmable Jag solution runs them at full brightness.

 

you mean the tail lights too? that's goofy...you could put an HID kit in the headlamps, they'll last longer for sure, but I'd also see if your local dealer could 'fix' the daylight lamp issue a little better than the florida one. Can't make it any worse.