A couple years ago one of my puddle lights began flashing the relay and interior lights so I pulled the bulb. It was recommended that I hard wire a ground to the light to stop the problem. My question is which wire to the light is the ground? I'm getting ready to strip the door skins off to replace the speakers and have some dings PDR repaired and I'd like to get that light up and running while I'm in there. Thanks

 

Did your interior lighting continue to work normally after you removed the bulb or did it then not work at all?
I doubt that the bulb is the cause of the problem but then it's a Jaguar and anything is possible. I had interior light flashing intermittently at first on only the driver's door that progressed to not working at all on the driver's door a few months later. The lighting continued to work normally on the other doors. The problem was a corroded connection in the driver's door harness to the door lock. There is a microswitch in each door lock and the signal from this is used to control the interior lighting. I was getting ready to remove the lock but I checked the harness first and found that a pin was so corroded that it had actually broken off at the base. This obviously provided an intermittent contact until it broke off entirely explaining the initial intermittent behaviour. Rewiring cured the problem and more than 1 year later I have not had any interior lighting problems since.

 

Pulling the bulb eliminates the bad ground circuit that starts the problem to begin with. The bulb doesn't cause the problem it's the fact that the bulb completes the circuit. Pulling the bulb stops the flashing but let's all other lights work. Already resolved by hard grounding the light fixture.

 

If you look at the wiring diagram (bottom LHS Fig 10.1 Interior Lighting) the puddle light is grounded by the door lock switch via the door switch pack when the door is open. By hard wiring the ground side of the bulb to ground you are by passing the switch pack and the door lock switch which would normally provide the ground path. The problem may not be with the actual door ground point itself but could be anywhere in the connections from the puddle light ground to the switch pack to the door lock switch to the door ground point. In my case there was no ground connection because of the corroded connector on the door lock harness. Because the bulb works when you independently ground it does not mean it's a ground problem - it is a problem in the circuit that normally provides the ground which includes the door switch and harness. Both sides of the door switch should be at ground when the door is open - if not then there is a problem between the switch and the ground point for that door.