Just happened tonight.
Went to unlock my XJR using the key fob, car unlocks and the high beams come on. Headlamp switch is in the off position. Started car then shut it off, locked car with key fob, high beams remain on even after five minutes. So I disconnected the battery, and reconnected the battery, high beams still on. High beam switch is in off position. Disconnected battery again to prevent discharge.

Earlier I had been working on the side marker lights.
Sockets and connectors completely corroded beyond repair. Decided to just cut the wires and cap them off separately. Keeping them sealed apart from each other to prevent any kind of electrical short.
Then I reinstalled the side marker lenses.

My reasoning for eliminating the side marker light connectors and bulb sockets, is difficulty in finding replacements. Even with the plethora of information here and knowing some VW models have the same socket and connector. I figured that I would replace them at a later date.

Is it possible that what I did by capping off each wire could be the cause of my high beams remaining on.

Any assistance in this matter would be greatly appreciated.

 

I would reinstall the side marker bulbs temporarily and see if the headlights go out.
If not then suspect faulty switch.

 

I don’t have the bulb sockets or connectors.
Maybe twist the wires together at each side marker, and cap of?

 

I have swapped the high beam really with the HID low beam relay. HID illuminated prior to the swap and after. My goal was to eliminate the relay.

 

Pulled fuses F8, F9 & F16 20A from the engine compartment fuse box. High beams stayed on, but not as bright as when you pull back on the stem switch. When reconnecting the battery, the left (driver) side high beam comes on, then about 20 seconds later the right (passenger) side high beam illuminates.

Perplexed

 

If they come on dimly with the fuses out then offhand (offhand 'cos I haven't had my 'brain starter coffee' yet this morning !) it sounds like some form of 'backward feeding' as a result of bad ground connections. Check the ground connections - they are a 'known problem' area on the 350.

 

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How it happened in order.
I capped off each side marker wire apart.
I reinstalled the side marker lenses.
I went to unlock the car with the key fob.
Just as soon as I heard the doors unlock and watched the side mirrors rotate outward, the halogen high beams illuminated.

Previously, during the day, while I was at work.
My better half heard the alarm on the XJR sound.
She terminated the alarm remotely, went outside to investigate and nothing near that would cause the alarm. She thought it to be odd.

Maybe those two scenarios assist in diagnosis.

 

Assuming you have the diagram of the FFB that's in the Owner's Handbook ... just checking you have the right relays ('cos they're not numbered on that diagram) ...

main beam is R2 ... one in from the left (left-most is R1) ie nearest fuse is F18

dip beam (HID) is R5 ... the only relay on the left, 'below' R1 and R2.

 

Those are the two that I swapped. R2 and R5
Took me a bit to understand the difference between DIP beam and Main beam. In the states the main beam is considered the high beam and the dip beam is the main driving lamp or low beam.

 

That's my sign, a new battery is in my future.

IOW's that could be low bolting in the alarm circuit.

Is there anyway, that... because of daylight or reflections or whatever... that the 194A parking light bulbs directly above the high beam h7's could have been the lights acting weird?
​​​
(I've caught mine doing crazy stuff. Probably after I installed bright LED's.)

 

It was and is the high beams. It’s puzzling.
IOW’s ???

 

In Other Words.

(Didn't help with the low volting typo, sorry.) Battery, ground, things controlling dropping volts are the usual suspect for the mystery alarms.

meirion1's switch check is probably a good place to start to try to figure out how power is getting to the bulbs then. Or start at the bulb and run back.

 

Not certain what I did that stopped the issue, but it did. This is the order of steps I took, just to see if it would work.
1. Disconnect battery.
2. Remove F8, F,9 & F16 fuses.
3. Remove R2 & R5 relays.
4. Remove headlamp ground connections G1 & G3.
5. Disconnected plug to both high beams.
6. Reconnected battery.
7. Start vehicle.
8. Switch headlamps on, and actuate high beams.
9. Ensure no headlamps illuminate.
10. Shut off vehicle.
11. Disconnect battery.
12. Reconnect G1 & G3 grounds.
13. Replace R2 & R5 relays
14. Replace F8, F9, & F16 fuses.
15. Reconnect battery.
16. Start vehicle.
17. Switch headlamps to on position and check for DIP beam illumination.
18. Actuate high beams, knowing they won’t illuminate. Shut off headlamps.
19. Shut off vehicle.
20. Plug high beams back in at the bulb.
21. Check to ensure high beams do not illuminate, as they did earlier. They did not. 😆
22. Start vehicle.
23. Switch headlamps on, then actuate high beams.
24. Check for high beam illumination. Good to go.
25. Shut off high beams, then flash high beams. All good.
26. Switch headlamps off.
27. Shut vehicle off.
27. Check to ensure high beams do not illuminate. They did not.

This may seem redundant. I was at a loss.
After checking as many ground connections that I readily could. They all were tight and without corrosion. I had also replaced DIP beam ballasts earlier and thought maybe they were faulty.
Eliminating the entire headlamp assemblies from the circuit and starting the vehicle then actuating the headlamps I thought, well I really didn’t know what I was thinking. Just an act of desperation, before I walked away for the day.
If anything changes, this forum will be the first to know. As of now the high beams are doing as they’re supposed to.

Thank you, everyone who contributed to my high beams issue. It is much appreciated.