Bad connection somewhere, obviously, but is this more commonly a problem in the stalk itself, or the relay? I have to pull on it anywhere between 1-10 times to get it to go to high beams, or to dip back to low beams. Obviously this is not good for oncoming traffic.

Jess

 

I have similar problems on the Series III sedans. In a couple cases the little grounding tab at the base of the stalk just needed to be cleaning. You'll see it if you remove the column cowlings. I'm pretty sure the Series III and XJS use the same switch

Mike be easier to begin by cleaning connections at the relay

Cheers
DD

 

Depending on the year of your car, 96 with the AJ16 engine, you'll have a Headlamp Relay Module mounted on the left side engine bay. Small black box. Your stalk controls the output to the headlamps for low beams, high-beams from here. There is a PC board with several rely inside. The relays can stick or the solder traces can break or lose contact. Taking the box apart is not hard as you'll have to remove the rubber potting near the connector and slide the innards out. There has been sucess at re-flowing the solder joints.
I have to do it to mine. Low beams work as soon as I turn the lights on but sometimes going from ow to high and back to Low, all headlights will go dark. I will have to keep at it or bring them back to high. Eventually, they will go to low and will just keep it there for the rest of the trip. Because our facelift cars headlight system works on a "momentary" ON and momentary OFF principle from the stalk, it engages a "toggle" logic in the module. So one pull turns on Hi beams, another pull, back to Low beams. In the earlier cars, the high and low power ran directly through the stalk lever, forward Low, back toward you, High.
The modules can be procured but are very expensive I heard.
See photo of where the module sits n the engine bay: Item 12

 

You can also purchase this Headlight Control Module and be done with it, if you aren't into finding and fixing solder joints.

DAC6902

Don't buy a used one. They're all at least 25 years old.

 

Assuming that Jess is talking about his 1989 XJS, there is no control module

Cheers
DD

 

Here's a pic showing the ground contact at the base of the stalk. I've seen a couple variations on this.

It dawns on me that an '89 may have the later style stalk but, still, there might be a similar grounding contact




Cheers
DD