Full Beam Problem

[shed]

Hi all.

I cannot get the main beam headlights on my 4.0ltr to stay on. All the lights work just fine, and the full beams will come on if I physically hold the indicator stork in the correct position, however as soon as I let go they dip again.

When the car is cold (ie only just started up), the normal procedure for putting the full beam headlights does work.

This leads me to think that this is not a problem with the unit on the steering column, but something - perhaps relay related - under the bonnet that refuses to engage when warmed by the engine.

As I have no idea how the system works, any idea that you can give me as to how the unit functions, and what may be the problem, would be gratefully received.

Thanks,
Ed.
'94 4.0ltr

[dhdove]

Shed

This sounds interesting. (tho, more likely highly frustrating for you......!)

If full beam comes on and stays on when held in the correct position.............then I assume it is working in "Flash" mode ie stalk pulled fully towards you.

To me this would indicate that the dip/mainbeam switch on the stalk has gone u/s.........ie does not switch from dip to main and back when operated.

I am confused by why it should work when the car is started from cold???
One could think that the headlamp fusebox/relay (inside front wing, nearside) was worn/corroded/heat damaged and failing when hot. However if this was the case I wouldn't expect mainbeam to work at all when the car is warm.?

My money, for what it's worth is on a failed/failing stalk switch.
It may be worth taking it out and cleaning all contacts with proprietary electrical contact cleaner.
Alternatively, relays are relatively cheap - less than ten pounds - so it may save some effort to replace this first with a new unit, and at the same time check the fuses/fusebox/wiring for problems.

Good Luck

DH Dove

[shed]

Hi DH. Thanks for getting back to me.

To answer your question "If full beam comes on and stays on when held in the correct position... then I assume it is working in "Flash" mode ie stalk pulled fully towards you"

This is correct. I can pull back the stork to flash the headlights. I can also hold the stork in this position to use full beam if I need to, however as soon as I let go the lights dip again.

Guess the only thing to do is give it a good clean and investigate replacing the relay.

Cheers,
Ed.

[Mark_B]

Hi

When you say 'I can make full beam come on', is that in actual fact full beam being added to the dip beam? (full and dip on together)

If so, (and if is the same setup as the earlier xj-s), there' a changeover relay behind the NS headlamp. If so I would also expect that it could stick on full beam as well as dip.

Might be relay. If the relay is the same as the earlier xj-s, the relay has an coil-activated armature, which makes a contact to full beam each time operated. every other activation alternates betwen full/dip, like a retractable biro mechanism.

[ptjs1]

Facelift headlights use a slightly different set-up to earlier ones and use a headlamp control module which takes the signal from the stalk switch and determines whether to light dip or main filaments.

I'd be tempted to look at the switch first and look to see if the control module is doing it's job properly.

Drop me an email with your email address and I'll email you the diagram showing the location of the components.

Paul

[shed]

Thanks to all for your responses.

I believe that it may be the case that both the dipped and main beam stay on if I'm manually holding the stork. When the car's cold though, it acts completely as it should, with only the main beams activated.

Ed.

[shed]

Paul - tried to send a PM, but not sure if it went through. Let me know if you've not received anything.

Cheers,
Ed.

[ptjs1]

Ed,

No email received as yet.

Paul

[ng4xjs]

Don't shoot me only trying to be helpful on he back of this. Two points.

The headlight control module (the big black box than sort of clips, hangs from the relay bracket on top of the left wing can quite easily suffer corroded terminals. A good spray with an electrical contact cleaner can work wonders.

Also is this car new to you? The reason I ask is that the main beam will only come on if switched the right way. The stalk needs to be flicked backwards and released. The flash function will only work if the headlights are not switched on. It's a crazy system really!

Good luck
Nick