Headlight ‘flicker’ on start up.

[Vedubber]

Noticed the other morning, that all of a sudden when I go to start the van, the nearside headlight flickers ‘off and on and off and on off and on’ during the start up procedure, where as the offside headlight will turn off, van starts and then very calmly comes back on again.

Once the light is on, I have no issues with flickering or anything.

I’ve tried the VW original headlight back in with different bulbs etc and still have the same issue.

I have checked earths and feeds and drawn a blank…

No fault codes either.

Open to suggestions.

 

[Stay Frosty]

Does your stop/start still work just incase the starter battery is on the way out?

 

[Vedubber]

Well…. Funny you should mention that, I have only just fixed the stop start by replacing the battery monitoring unit on the negative.

 

[Dellmassive]

LED or Halogen?

OEM lights?

 

[Vedubber]

LED or Halogen?

OEM lights?

All of them. Literally.

 

[Stay Frosty]

My original VW fitted in 2017 Moll battery died at three years old and the VW assistance replacement Varta died this year so now have a larger 95Ah AGM type Bosch fitted thanks to a lovely fellow forum member, thank you Garry.
This is on a modest 102 hp T6 but the standard 75Ah EFB battery (not AGM) doesn't seem fit for purpose and can throw up a lot of random fault codes as it droops under load.

 

[Vedubber]

My original VW fitted Moll battery died at three years old and the VW assistance replacement Varta died this year so now have a larger 95Ah AGM type Bosch fitted thanks to a lovely fellow forum member, thank you Garry.
This is on a modest 102 hp T6 but the standard 75Ah EFB battery (not AGM) doesn't seem fit for purpose and can throw up a lot of random fault codes as it droops under load.

Battery is 3 months old. And when not in use it’s connected to a trickle charger. And as mentioned the drivers side headlight is absolutely fine.

 

[Stay Frosty]

That's me out of ideas then as long as the new battery is beefy enough.

 

[Dellmassive]

Can you get a video clip of the front lights and post a lift no to it here?

On YouTube or drop a link from your gallery

 

[Vedubber]

It’s hard to see but you can see that flickers of and on. The other side just goes off once and comes back on.

 

[Dellmassive]

Have you tried swap in the bulbs to see if the fault stays on one side or follows the lamp?

 

[Stay Frosty]

Led driver on one lamp a bit more sensitive to volt drop than the other, you get a moderate lunge there listening to the starter getting a grip.

 

[Vedubber]

I have tried the following bulbs in the nearside

HID - very sensitive
H7 LED
H4 LED
H4 incandescent bulb

Transporter HQ lamps
Standard H4 head lamps.

I’ll record the HIDs later to give you a better idea.

 

[Stay Frosty]

HID lamp will require an high voltage surge to strike so is always going to flicker let alone also a few seconds to warm the gas envelope and get a decent arc going for maximum light output... main reason you don't use them in main beam slot.
I reckon you're getting a bit of a voltage dip on starting that's enough to make possibly that one Led lamp built in driver struggle, as Lee @Dellmassive said earlier swap that lamp to the other side to check for the same result there.

 

[Vedubber]

HID lamp will require an high voltage surge to strike so is always going to flicker let alone also a few seconds to warm the gas envelope and get a decent arc going for maximum light output... main reason you don't use them in main beam slot.
I reckon you're getting a bit of a voltage dip on starting that's enough to make possibly that one Led lamp built in driver struggle, as Lee @Dellmassive said earlier swap that lamp to the other side to check for the same result there.

Yes totally.

Just never had the issue when I was swapping out to the HIDS, and boy have I got through some HIDS to find the right ones and never noticed it at all during this time. Just seems strange how all of a sudden I now have the issue with only the left one.

Only things that have changed recently was a new battery monitoring cable to make the stop start work again. And adding fog lights into the BCM.

The earth for the nearside headlight is located under the front crash bar on the offside by where the horn is, and I have cleaned this up to ensure a good connection.

Dipped beam pulse width modulation is disabled as the HIDs will not work with it turned on.

Appreciate all the feedback

 

[Stay Frosty]

Not sure what the battery monitoring cable would be is that the neutral shunt at the starter battery neutral terminal that keeps the BCM informed of battery state to cut stop start from working when the battery isn't strong enough to perform the job reliably?
Also what battery type and Ah rating?

 

[Vedubber]

 

[Stay Frosty]

Are they THQ type headlights where you can swap the lamps over from the left headlight to the right and vice versa ie. a small reflector behind a projector lens, if so could you try swapping the lamps over per post 11 and see if the left headlight still flickers?

 

[manfrotto]

Could it be an issue with the sterter motor? Maybe it is a bit tired and needing more power than normal. You could check the voltage drop during starting.

 

[Vedubber]

Are they THQ type headlights where you can swap the lamps over from the left headlight to the right and vice versa ie. a small reflector behind a projector lens, if so could you try swapping the lamps over per post 11 and see if the left headlight still flickers?

Have now swapped everything over between OEM lights and THQ lights, from side to side and the Problem always remains on the left side.