Jaguar Repair: Jaguar XJS, jaguar xjs, light fuse

Question
One of my reverse lamp bulbs went out. Then the stop lamps went out. Then the headlights stop working. The turn signals stopped working. All of this happened at the same time.

Answer
Hi Joseph,
Never try to diagnose electrical problems on several items at once. Always pick only one item and trace it down from power to load or from load to power supply.
I would start with the head lights. It is not necessary to remove all of the head light bulbs to test for power to them. You can test with a test light at the head light fuse panel on the left fender well under the hood with the head light switch on. You need to test fuse # 2,3,4 & 5 for power. If you have power then you do need to test the wires at each head light. If you don't have power you need to test the headlight relay just in front of the fuse panel.
Direct power comes to the relay by a brown wire on pin # 81A and power comes from the head light switch by a blue wire on pin # 56. If you have power at all places that you should and the bulbs are good then you need to test the flasher switch on the column for a good ground. If you find all the bulbs burned out, you need to test the charging system and the engine and battery grounds.
Howard