Flickering dash lights

[maisbitt]

Went for a short trip out on Sunday night and my dash lighting was going mad. Everything that is backlit (the dials, Highline computer, the head unit screen, climate controls etc) was flickering between the brightest setting and a low setting (that I have set it to) at least every second. It was pitch black outside, so definitely not one of those threshold situations when the car maybe teetering between it sensing light and dark outside. The headlights were on and not flickering.

Anyone else have this happen to them? It was hugely distracting. Next time I used the car it hasn't happened. I haven't driven this car in the dark much since getting it in June, but this is the first time it's happened to me.

[RW1]

Known problem. No fix yet (since April 2010).

Caused by voltage surge of alternator during acceleration or static acceleration of the engine.
Flickering is the electronoc components momentarily shutting down due to their own over voltage protection circuits activating. Affects RCD/RNS510 screen, dash insert, internal lighting/door switch electrics.

"Postpone repairs till the result of the analysis is known, which will be published here."

"Explain to the customer that his vehicle operates according to the specifications and that there is no fault. We are
working on a solution of the complaint."

No warranty instructions, so it will be "dealer good will" if you take it in I suspect.

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To me, it points to either a slightly too slack an alternator belt which causes the alternator belt to initially not increase the rotation speed of the alternator under load exactly with the engine speed increasing. Then the belt "whips", making the alternator spin faster quickly to the new working speed. Under this condition, the voltage increase on any alternator is not caught quickly enough, so a momentary voltage surge above 14 volts occurs. The usual sign is darkened bulbs glass. Maybe too early to see the darkening but rear sidelights would be the tell tale with being on all the time.

Not by any chance left the Scirocco standing recently. If the voltage is down from the battery, the car usually starts making a short tolling tone warning noise through the front door speakers as the battery management module informs the the Central Electrics Controller 09 that it is shedding electrical loads to save the battery charge. Fault 00907 will sometimes appear eventually. But initially the tone starts randomly and can be heard outside the car. In association with this the Central Electronics starts showing an error but no fault as seen in the first PC screen shot in the link above.

May be the battery is low and the electrical load last night was causing the alternator belt to "whip". Charge the battery up so the high battery charging load on the alternator is removed and see if it persists. If its gone, then the belt tensioner needs looking at for strength or stiffness in its movement.

Or your driving habits have too many short journeys requiring frequent engine starts which don't allow the alternator to charge the battery enough. Batteries take a fair while to change their charge state when being charged, so a battery charger on trickle charge (4 amps) compatible with "on car" charging needs to be left on for 12 hours-ish to bring it upto full charge. Even though the engine may have been running for an hour, the battery doesn't change its overall charge state when a car is getting low usage/frequent starting.

OR

the voltage regulator on the alternator is sluggish when repsonding to alternator rotation speed changes ie. voltage changes, the voltage regulator does not immediately stop the voltage surge.


But as above, VW haven't sorted it. My thoughts above are from other cars where I have seen similar, not Scirocco Mk3.

My own suffers from the battery charge state slowly decreasing and not getting enough charge. In summer its OK, but in winter, I end up charging the battery about once a month to bring the charge state back up. Don't suffer from the flicker but that is maybe because the alternator belt tensioner is operating correctly even with higher current battery demand and so the belt not whipping.

C.

[maisbitt]

RW1: You don't get a more comprehensive reply than that!

I rang the dealers today to make an appointment, but my registration isn't being picked up by their computers (didn't buy from the dealership I rang to do warranty work), so i'll have to note down the VIN number after work to give to them. Sure enough, I go on a comparison website and enter my reg number to see what it throws up and my car is regognised on "Go Compare" as a Vauxhall Meriva!

My drives generally involve a minimum of 10 miles, with a few shorter journeys a week to the supermarket - nothing to hammer the battery. Not the first time i've seen the flicker, but last time it happened, it was an overcast day and I assumed the light sensor couldn't decide whether to have the light on or not, like it was sitting at the threshold between lights on and lights off.

The other night I was maintaining 50mph for about 2 miles when the flickering happened. I haven't driven much in the dark dueto the late sunset since I had it, but this is a safety concern for me, due to the high level of distraction while driving at night.

I need to take the car in for something else anyway - there is an annoying rattly-buzz that appears to be coming from around the airvents above the RCD unit that only really happens when you maintain around 1200rpm in 4th or 5th gear - that's been there since day 1.

[RW1]

My drives generally involve a minimum of 10 miles, with a few shorter journeys a week to the supermarket - nothing to hammer the battery.

Not about hammering, its about the state of the battery charge. Bit like Ni-cads, modern batteries assume a charge level according to your driving habits. The way out is a long run above 2 hours duration. If temp. resolved, it would point to the tensioner coupled with a low charged battery.

As above, a battery charge may stop it temporarily until the battery resumes the state of your driving habits upto a couple of weeks later.

A quick check is to pop a DVM on the battery terminals after being stopped for 12 hours but not restarted. What voltage is it then?

C.

[RW1]

@ maisbitt
Did this ever get fixed?

C.

[maisbitt]

Yep, they replaced something that controls the lighting levels and it hasn't happened since. They were reluctant to give me any specifics as to what was replaced. Is this now happening to yours?

[RW1]

No, just curious as to what happened.

C.

[salsajoe]

Happened to me a couple of times recently on journeys of about 60 miles about mid-journey. The dash lights, touch screen and MFD suddenly brighten. Due for first service Thursday so will add to the list!