Dashboard light contrast faulty!?!?

B

basssound

Registered User
Joined
Dec 1, 2010
Messages
199
Reaction score
10
Points
16
Location
NULL
Noticed earlier when drivin the car that the radio and dashboard illumination was altering itself, constantly going very bright and then very dim!

Anyone come across this before?

Car is a 2007 TDi Sline
 
As in go brighter with increased engine output?
 
Yeah!!!!! I noticed when on idle and then revving the dash would go brighter and then dim on idle :'(

This sounds expensive!
 
I thought this is normal. More revs = more electrical power generated by the alternator so you should expect a spike.
 
Errr no, the illumination is set by the contrast adjuster on the headlight switch panel, basically a potentiometer.
Just looking to see if peeps have had this fault before.
 
Mine does this. 2004 3.2. its done it since about 2 years old. Nothing to worry about. Its not revs related or anything to do with the potentiometer. Its just one of its many strange peculiarities :)
 
Well this is obviously something that has gone wrong as I've never noticed it lol
I'll get to the bottom of this ;)
 
My thoughts were its prob a voltage drop as they get dimmer rather than brighter than stock, turning the pot dosnt help #It could be a dry joint somewhere on a resistor but to be honest mate ..........life is to short :yes: mines been doing for 4 years and it dosnt get any worse or better. You will not notice it after a while :)
 
The instrument lighting on my 2006 sportback changes depending on how bright it is outside. In a tunnel the lights dim (presumably because they don't need to be so bright) and then brighten when back out.

If you put your thumb on the speedo dial just below 12 o'clock you can test it. Thumb on goes darker , thumb off goes brighter. The dial on the light switch is the over-riding brightness control.
 
mike foster said:
The instrument lighting on my 2006 sportback changes depending on how bright it is outside. In a tunnel the lights dim (presumably because they don't need to be so bright) and then brighten when back out.

If you put your thumb on the speedo dial just below 12 o'clock you can test it. Thumb on goes darker , thumb off goes brighter. The dial on the light switch is the over-riding brightness control.
Click to expand...

On mine as i dont yet have auto lights it would do it when i went into a tunnel the dials would come one and then fade out... annoying as hell as once im in the tunnel i would have to switch the lights on to see how fast i was going. This has now been switched onto constant dial lights on via VCDS! no matter what time of day the dials remain to glow!

As for the OP... i have recently seen this happen on my sportback to the extent of the interior dome light and headlights (before i switched to xenon) seem dim and get brighter when i rev. Had my alternator tested and results came back fine... didnt seem right so i had the battery tested and its below the recommended limit. Still enough to drive with but have been warned to change it incase of battery failure.
 
The interior lights shouldnt flicker/pulse etc! It could be as Paddy says, the reostat on the light switch.
 
There may be a clue in the remarks posted by member 'itwasntme187', when he mentioned the battery. A good battery should hold very close to 12.65 volts when at rest. If indeed the battery voltage is varying, it is quite probable that the interior lights will change their brightness. But if the battery voltage is changing by several volts, there is a good chance that the battery is on its way out. A simple check would be to put a voltmeter across the battery terminals. Look at the voltage when at rest (fully charged) and it should be close to 12.65. if it is low, then suspect that the battery is at the end of its life. At least try another known-good battery and see what happens.
 
mike foster said:
The instrument lighting on my 2006 sportback changes depending on how bright it is outside. In a tunnel the lights dim (presumably because they don't need to be so bright) and then brighten when back out.

If you put your thumb on the speedo dial just below 12 o'clock you can test it. Thumb on goes darker , thumb off goes brighter. The dial on the light switch is the over-riding brightness control.
Click to expand...

The sensor is on the right had side of the speedo markings underneath the 140mph or 160mph symbols...
 
I agree with Geraldy but to be honest to check a battery you need to do a drop test ie measure the voltage while cranking the starter. Also if its brightening up when you rev i would check the voltage regulator as well because you shouldn't really notice this with a modern alternator as it should give out a constant voltage even at a fast tick over unless you have a big load across it like HRW and heated seats on etc
 
Also got to remember, its the central electronics module that controls to power to certain items. Not like in the old days when every component was more or less linked straight to the battery and not controlled by canbus.
 
Khufu, this problem seems to be in some way linked to engine revs. That is suspicious. If indeed there is a voltage regulator included in the central electronics module for common power bus's, then it is clearly not working properly. Perhaps there is a control field somewhere in the central module, accessible through VCDS which sets this facility? I still think one should at least try another battery, or as has been suggested above by Paddy, do a proper battery load test. Other potential areas would be the alternator itself. Perhaps it is overcharging the battery and causing a large voltage change.
 
Yea the alternator should have a regulator built in before the canbus but after that i would be lost :)..its quite possible the voltage for the dash lighting is not 12v anyway as far as i know..
Mine will go bright and dim in a traffic jam at basic 625rpm tick-over. I did look into it a year or so ago but while my suspicion was battery it showed no sign of problem in all that bad weather last year and if it will spin my V6 at -10c then there cant be much wrong with it. Could just be a bad earth so back to where i started with a dry joint somewhere ?
 
Last edited:
You must log in or register to reply here.

Similar threads

Jetley
Dashboard faulty
Replies
0
Views
308
Jetley
Jetley
S
2010 Audi A3 faulty dashboard
Replies
0
Views
517
stubo300
S
Woob
Quattro dashboard light
Replies
7
Views
744
spawn616
S
Caspper...
Tail light faulty
Replies
5
Views
522
baderlfc
B
StatedRain
Faulty brake light?
Replies
8
Views
506
SootySport
SootySport
Top
Back