lights pulsing?

[Jackstrath]

hey all

Quick question , i had a search but couldnt see anything

since iv had my X5 iv noticed when driving (it might do it while still but not sure) my lights pulse , not super dim , but enough that you notice it , , have everything off bar the car and lights but full on heaters and seats stereo ect makes zero odds ,

its a 2003 model and looks like its on its original battery , since its done it for about 6k (thats when i got it 6k ago) its not got worse so rulled out the alternator , was thinking a bad earth or the battery on its way out?

any help would be appreciated thanks

[X5Sport]

If it's a 2003 battery that has done extremely well.  6 years is about the average service life for one these days.

Do all the lights flicker - including dash and instrument illumination?  Are your lights OEM or modded?

The external lights have a checking circuit to make sure the bulbs are OK but you should not see that and I thought it was a 'cold' check anyway.  Some non-OEM lights do flicker.

It sounds as if the alternator is charging as these cars are unforgiving of poor battery charge states.  Do you only get this with the engine running?  Does it change with engine speed?  If you have access to a multimeter then see if the needle flickers with the engine running?  An oscilloscope trace would show it straight away if it is the alternator or regulator pack.  You should get about 14.4V on a good battery & charge state with the engine at a fast idle.

Richard

[Jackstrath]

yeh the dash lights flicker aswell , its bairly noticeable tbh , but i have a sharp eye , one of my mates can see it , the other cant , the battery is fine as i checked it first , and havnt had any error codes ether that you normally get , the guy before me kept it on trickle charge as he was a offshore guy 

speed makes no difference , nether does engine revs


i just had a google and it seams to be a common issue on them by the looks of it , only way to stop you seeing it is if you fit HID's

The dash isnt noticeable as you have to stare at it and you dont tend to do that when driving haha 

[X5Sport]

You may be one of those persons sensitive to low frequency lighting flickers.  The regulator does not put out pure DC, you get a pulsed wave-train.  Do you have the same issue with computer monitors, especially CRT type?  50Hz ones used to drive me nuts and when 60Hz ones appeared they were a godsend.

[Stevejspm]

I know it's a completely different vehicle but I had EXACTLY the same symptoms as you with my Renault Master van. One evening driving home from a job my lights went dim followed by several dash warning lights. Pulled over & stopped van, tried to restart & battery was flat. Turned out alternator was knackered & stopped charging the battery.
The flckering/pulsing interior & headlights lasted for weeks prior to the alternator finally packing up. I was informed after changing the alternator that it was more than likely the diode pack or regulator within the alternator a fault.

I'm not saying your issue is alternator but it's weird that my van suffered the same symptoms.....it's certainly worth getting it checked.

Good luck!

[Steamyrotter]

[quote="X5Sport"]

The external lights have a checking circuit to make sure the bulbs are OK but you should not see that and I thought it was a 'cold' check anyway.  Some non-OEM lights do flicker.

[/quote]

There is a Cold check, a Hot Check and i believe a Working check..
The LCM (Light Control Module) pulses the line when lights off to check they are there / there is a circuit.
It looks for the resistance (by passing a low current pulse through them) and checks its within limits.
As hot and cold will give different resistances there are 2 check modes.
When the lights are on the LCM monitors the current drawn and acts on that.
This is why upgrades from halogen to HID cause issues as the resistances of the ballasts are different and they take less current on the whole.

I have just changed my front side lights to SMD LED angel eyes and also replaced the reversing lights with LED.  These actually flash a few times due to the low current needed to illuminate them is being supplied by the cold check.

If it is a problem then all the check modes can be turned off individually.