Disco 3 (LR3) Flickering light problem

hi all.

I recently purchased a Disco 3 HSE off a friend of mine.

Last month he had a problem with it leaving him stranded after electric problem which turned out to be a faulty alternator.

Was duely replaced with a genuine LR alternator and all good.

But this weekend I noticed that the interior lights seem to pulse when parked with the engine running and the reverse lights do it also.

Battery light isn’t on and has no problem starting in the morning.

Just wondered if anyone has any suggestions on where to look or what problem I might have?

Cheers chris

Co-Pang-Yang said:

hi all.

I recently purchased a Disco 3 HSE off a friend of mine.

Last month he had a problem with it leaving him stranded after electric problem which turned out to be a faulty alternator.

Was duely replaced with a genuine LR alternator and all good.

But this weekend I noticed that the interior lights seem to pulse when parked with the engine running and the reverse lights do it also.

Battery light isn’t on and has no problem starting in the morning.

Just wondered if anyone has any suggestions on where to look or what problem I might have?

Cheers chris

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Think I'd get a multimeter to test the output when its running to check if the alt is giving out full voltage, You want atleast 13.8v to 14.4, above 14 being ideal.
And then you can see how much its surging. I take it its only the power surging and the engine is idling fine?

plus 1 what @Jamiegreen has said

there has also been reports where some new alternators have been faulty , should only fit a denso one

if an alternator has failed it can take the battery with it

would also ensure the alternator connections are nice and tight and at the battery and the earths

The alternator will output up to around 15.5 volts

with the engine running , out everything on, screen, etc and see if the pulsing stops

there is also a guide which u may find useful

http://www.disco4.com/forum/post1366423.html#1366423

does it still pulse when u raise the engine to 1,000 revs

just a thought , have u got leds fitted

is it only the interior and reversing lights that are pulsing

plus if it helps , ur HSE has a hidden menu, always best to use a multimeter for testing, it was just something i remembered for reference

https://www.disco3.co.uk/wiki/Hidden_Menu

Jamiegreen said:

Think I'd get a multimeter to test the output when its running to check if the alt is giving out full voltage, You want atleast 13.8v to 14.4, above 14 being ideal.
And then you can see how much its surging. I take it its only the power surging and the engine is idling fine?

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totally agree in what you’ve said , suprising how high these run at , when i start mine it’s around 15.5Vdc and then slowly drops over time

Cheers for the great info lads, gonna look into the secret menu and see what that brings up plus get the voltmeter out.

Thanks again.

Found secret menu and from there battery voltage showing 12.5v with ignition on.
10v whilst cranking then after 5 seconds of running it’s up to 14.5v

However, turn the interior lights on and heaters up full wack and voltage drops to 13v

Co-Pang-Yang said:

However, turn the interior lights on and heaters up full wack and voltage drops to 13v

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hi mate

to me it sound like the new alternator has gone, if u raise the engine speed to 2000 revs what is it then

as from 14.5 volts it shouldn’t drop but maintain the voltage when u start loading it

however really need a multimeter onto the battery to test it 100%

if it has gone, the alternators to fit are only denso , cheap or recon for some reason don’t last , hopefully it hasn’t taken ur battery with it

assume u can’t hear any slip on the belt and is all ok

these alternators are controlled by an external controller and will run up to 15.5 volts

the other guys should be along to see what they also think ,

have u got a meter that does AC volts , if so plse, with the engine running put it across pos and neg posts of the battery and see what u get plse , many thks

plse let us know how u get on

That’s good then, had a new genuine alternator a couple of weeks ago

Co-Pang-Yang said:

That’s good then, had a new genuine alternator a couple of weeks ago

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it’s good then at least it can be replaced under warranty and a genuine denso

Tried it at 2k rpm and getting 12-12.5v

Co-Pang-Yang said:

Tried it at 2k rpm and getting 12-12.5v

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yep, sounds very low to me , but u will know more when u get a meter onto the battery , giving a 100 % reading and not going through the system but at source

plus, plse and out of curiosity try the AC meter test across the battery posts with the engine running and see what readings u get plse , thks

Just chucked the volt meter across the battery and engine off was reading 12.6v.
Then engine running goes up to 14.8v.

No clue with electrics so is that more likely alternator or battery?

Can’t even see the alternator to try and test that direct

Co-Pang-Yang said:

Just chucked the volt meter across the battery and engine off was reading 12.6v.
Then engine running goes up to 14.8v.

No clue with electrics so is that more likely alternator or battery?

Can’t even see the alternator to try and test that direct

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that sound more like it , did u set ur meter to ac as well and tested across the posts with the engine running plse,

is it only the interior and reversing lights that flicker , my only thought them is if the previous alternator failed could it have damage the led diode sensors

however , think the best course of action is to get the battery and alternator tested out by a garage first , in order that no damage can be done and be established battery and alternator are ok

Seems to be just interior lights and reverse. Though not checked the rest of the tail lights.

Yes I’ll have to take it to my mates garage at the weekend to try and figure out what’s going on

Probably battery is past it’s best, alternator seems to react how it should according to your figures

freelance said:

Probably battery is past it’s best, alternator seems to react how it should according to your figures

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read alot of reports where when the alternator fails it can also destroy the battery , but sometimes lucky if caught in time

i’m wondering if maybe with the previous alternator failing if it’s possibly damaged the diodes in the interior and reversing lights if there leds ???

alternator should output up to around 15.5 volts

Just to clarify that point all the interior and exterior bulbs are not led but standard spec.
Looking at the condition of some of them they look to be the original 14 year old bulbs.

I’m leaning towards battery as well but will try more investigating before chucking £100 at a new one.

Co-Pang-Yang said:

Just to clarify that point all the interior and exterior bulbs are not led but standard spec.
Looking at the condition of some of them they look to be the original 14 year old bulbs.

I’m leaning towards battery as well but will try more investigating before chucking £100 at a new one.

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Think halfords will test your battery with their tool if you take it to them, might be better telling them you think you need to buy a new battery and then just say you'll leave it once they've tested it. Worked for me before as they are so expensive I wouldn't get it from them.
And I think I'd avoid alternators from the breakers yard, I had mine from once and its starting to go after 6 months or so, well the regulator most likely, sometimes 12.2.. sometimes 14.4.. its a d2 though so the reg is built in to the alt, and they are cheap enough to buy as gary said, but obviously use the warranty if thats the case.
And if need be try and get a good branded battery, I spent £100 on a pos battery over here in Romania and the thing barely holds 12v, 11.4 in the cold.. -20. Guess it was sitting in the shop for a few years.