Disco 2 Both Main Beam Headlights Stopped Working

2003 Disco 2 Td5 (facelift headlamps)

Driving yesterday, got dark just before I got home - noticed both main beam (dipped beam) lights not working when I turned the lights on at the stalk on the steering column.

Okay, checked today:

• Did nothing, changed nothing, issue just spontaneously appeared with no obvious possible cause and effect - not as if I recently installed new lights or something.
• Parking lights work, High beam lights work, Fog lights work, Indicators work, Rear lights work.
• High beam blue light comes on dash when high beam is activated when pulling the stalk.
• Pulled out both LH and RH dipped beam fuses F9 and F10 (10A) under steering column - both fine visually.
• FL10 (30A) looks okay visually.
• Couldn't possibly have both the globes go at the same time eh (put pair of new Osrams in 18 months ago without issue)?

So, the column stalk switch feels okay - it was replaced around 10 years ago by LR dealer. Is it likely to be this bugger again?

Anything else I should test/check?

Repair the stalk switch (part number STC 4017) if it indeed is the switch that is faulty, or maybe buy a new switch or even a used switch from the wreckers? Can you overhaul repair the switch if it is faulty?

I believe it's not too difficult to sort this one yourself if it is a faulty stalk switch - is that right? Any comments, things to look out for?


[PS If I do have to remove the stalk switch then I will be sure to disconnect the battery 30 min beforehand - don't want airbag/s going off!]

Have you checked the bulbs?
As unlikely as it seems I was not expecting both bulbs to have failed at the same time on my sons car but they had.
I too tried the fuses first but when I pulled bulbs, sure enough both failed!

Bantam1 said:

Have you checked the bulbs?
As unlikely as it seems I was not expecting both bulbs to have failed at the same time on my sons car but they had.
I too tried the fuses first but when I pulled bulbs, sure enough both failed!

Click to expand...

Okay - reverse lottery, both failing at the same time?! I guess I really should pull them both out to be 100% sure!

You dont have to pull the bulbs before you measure for voltage against earth(black wire) in the connectors on the pin which feeds the non working lights... though you say that "main beam" doesnt work but high beam does which is confusing as it's the same thing for me, i presume that you named "main beam" the dipped beam then and for that it's blue/black wire for RH and blue/pink on LH. If you dont have voltage the bulbs are ruled out and the problem is elswhere, can be the stalk, investigation is needed

Bantam1 said:

Have you checked the bulbs?
As unlikely as it seems I was not expecting both bulbs to have failed at the same time on my sons car but they had.
I too tried the fuses first but when I pulled bulbs, sure enough both failed!

Click to expand...

Totally agree. amazing though it may seem. this has happened to me and the Mrs more than once. Maybe one goes and that creates a slight surge in power to the other? Just guessing here as I am not an electronicist. But if both bulbs were fitted at the same time.....

sierrafery said:

You dont have to pull the bulbs before you measure for voltage against earth(black wire) in the connectors on the pin which feeds the non working lights... though you say that "main beam" doesnt work but high beam does which is confusing as it's the same thing for me, i presume that you named "main beam" the dipped beam then and for that it's blue/black wire for RH and blue/pink on LH. If you dont have voltage the bulbs are ruled out and the problem is elswhere, can be the stalk, investigation is needed

Click to expand...

Yes, said main beam, but that's of course dipped beam - both just stopped working! When I use the stalk to select high beam then it comes on as normal and the blue light high beam indicator shows on the dash. All other exterior (and interior) lights, including indicator, brake and reverse are working. Got me beat, that's why I thought it must have something to do with that stalk switch again (was replaced 10 years ago).

sierrafery said:

You dont have to pull the bulbs before you measure for voltage against earth(black wire) in the connectors on the pin which feeds the non working lights... though you say that "main beam" doesnt work but high beam does which is confusing as it's the same thing for me, i presume that you named "main beam" the dipped beam then and for that it's blue/black wire for RH and blue/pink on LH. If you dont have voltage the bulbs are ruled out and the problem is elswhere, can be the stalk, investigation is needed

Click to expand...

The lights are the facelift type - so high beam lights separate from dipped beam lights. As I said, high beam work, fog lights (in bumper) work and side/parkig lights work. Just seems strange that both dipped beam went at the same time. Will get the multimeter and check for voltage at both fuses (separate fuse for each dipped beam).

I know how the circuit is, you have to check in the lamp's connector

sierrafery said:

I know how the circuit is, you have to check in the lamp's connector

Click to expand...

Okay, so I'll get the multimeter and check for voltage (with the lights switched on) at the LH and RH connector?

Intestinalworm said:

Okay, so I'll get the multimeter and check for voltage (with the lights switched on) at the LH and RH connector?

Click to expand...

Yes, on the wires i pointed, those are for dipped beam

sierrafery said:

Yes, on the wires i pointed, those are for dipped beam

Click to expand...

Okay, I'll check this when I have time spare in the next 3-4 days. Thanks.

Strange thing today though - had to do a round-trip to pick something up (before it got dark) - out of nowhere the amber warning light on the dash for the "raising the rear suspension" came on whilst I was on the freeway for no reason! Nothing happened, but I can't work out what caused the light to come on (only ever came on before when I pressed the button). After I got home I turned off the ignition, waited and turned it on again - warning light gone! Strange? Wonder if there's a (weird) link with the dipped beam? Might have to put it down as a strange aberration unless it happens again!

Okay, just recalled one more thing! We drove in a lot of rain (very heavy) several days ago with the Disco. Anyway, I noticed the carpet on the front passenger side was also wet several days ago immediately after the rain. I took out the rubber floor mat and soaked up the wet carpet with towels.

Could this ingress of water have got to the BCU unit (never seen it before but know it is behind the glovebox somewhere)? Could this possibly be linked with the sudden loss in dipped beam (dipped beam stopped working)?

I also have to also find out how/where the water got in here? I don't have a factory-fitted sunroof - I have an after-market Webasto that I have never had any issues with.

sierrafery said:

Yes, on the wires i pointed, those are for dipped beam

Click to expand...

blue/black wire for RH and blue/pink on LH. If you dont have voltage the bulbs are ruled out and the problem is elswhere, can be the stalk, investigation is needed

Bit of a novice with the multimeter, but assuming then I access the relevant wires from behind at the RH and LH light connectors: RH light - blue and black wires, and LH light - blue and pink wires, and then check for voltage (12V ideally?) across them when the light switch is switched on at the stalk? No voltage means problem upstream, and voltage means I do have blown globes?

Hoping the multimeter probes can poke in - I didn't get those long thin wire probe attachments the auto electricians use as an accessory.

Intestinalworm said:

blue/black wire for RH and blue/pink on LH. If you dont have voltage the bulbs are ruled out and the problem is elswhere, can be the stalk, investigation is needed

Bit of a novice with the multimeter, but assuming then I access the relevant wires from behind at the RH and LH light connectors: RH light - blue and black wires, and LH light - blue and pink wires, and then check for voltage (12V ideally?) across them when the light switch is switched on at the stalk? No voltage means problem upstream, and voltage means I do have blown globes?

Hoping the multimeter probes can poke in - I didn't get those long thin wire probe attachments the auto electricians use as an accessory.

Click to expand...

Don't have a Facelift, so don't know why, but is it really that hard to get a bulb out?
Once the bulb is out you can test it with your mulitmeter set to Ohms and the connections in the bulb holder set to volts, i would have thought.
(@sierrafery will soon say if I am wrong!)

Intestinalworm said:

blue/black wire for RH and blue/pink on LH. If you dont have voltage the bulbs are ruled out and the problem is elswhere, can be the stalk, investigation is needed

Bit of a novice with the multimeter, but assuming then I access the relevant wires from behind at the RH and LH light connectors: RH light - blue and black wires, and LH light - blue and pink wires, and then check for voltage (12V ideally?) across them when the light switch is switched on at the stalk? No voltage means problem upstream, and voltage means I do have blown globes?

Hoping the multimeter probes can poke in - I didn't get those long thin wire probe attachments the auto electricians use as an accessory.

Click to expand...

blue/black (BU) on the diagram means a blue with black trace wire and it's positive feed(same for the blue/pink wire).... measure across these and the black wires in the plug as black is earth, with light switch on off course.... and yes for the last question

Bulbs (dipped beam) checked and okay. Back to fuses F9 and F10 then ==> ignition on and stalk switch dipped beam lights turned on ==> no dipped beam lights as before and with multimeter now across both F9 and F10 terminals at the fusebox under the steering wheel (fuses removed) there was no voltage drop = 0V measured! I conclude therefore that the stalk switch is likely faulty (dipped beam not working, but indicators, high beam and side lights are okay).

So, removed the switch after disconnecting the battery earth (don't want air bags accidentally going off) - used this as a guide:


Nothing visually obvious with the switch once removed. Decided not to take the switch apart and check/fix as I need to put it back in for now so I can use the Disco tomorrow morning.

Will just go ahead and buy a Lucas (OEM) switch now and then I can have a "fiddle around" with the old switch once the new one is installed!

Any thoughts/comments anyone?

Intestinalworm said:

...now across both F9 and F10 terminals at the fusebox under the steering wheel (fuses removed) there was no voltage drop = 0V measured!...

Click to expand...

That's not the way to check things, that measurement is completely irrelevant that way, you have to measure on the fuse in situ against earth to check the switch
Unplug the stalk and make a bridge with a wire across pins 2(blue/red) - 6(brown/purple) and if the dipped beam doesnt come on the problem is not the switch, if you get the lights with the bridge then replace the stalk...did you check fusible link FL10 engine bay?

If the fuse/s (F9 and F10) are in situ then I can't connect the multimeter lead probes to them - all I see is the plastic top of each 10A fuse?

Pointed with red arrow where to measure both sides, positive probe there and negative to earth there must be 12V with switch on

sierrafery said:

That's not the way to check things, that measurement is completely irrelevant that way, you have to measure on the fuse in situ against earth to check the switch
Unplug the stalk and make a bridge with a wire across pins 2(blue/red) - 6(brown/purple) and if the dipped beam doesnt come on the problem is not the switch, if you get the lights with the bridge then replace the stalk...did you check fusible link FL10 engine bay?

Click to expand...

Checked FL10 (30A) under the bonnet - continuity with multimeter was good.