HELP! Bulb warning light constantly on - i can't find the problem

[garyRR]

I have a 2012 Altea XL 60,000 miles.

The bulb warning light started coming on the first time I touched the brake in an ignition cycle (and would then stay on until ignition off). Sure enough, some of the LEDs were out in the 3rd/high level brake light and I replaced with a new aftermarket part.

Now, when I brake the warning light doesn't come on, however if I go so far as to turn on the side lights or press the hazard warning lights, the warning light immediately comes on. I don't know if this would still have been the same before, as the warning light came on as soon as I put my foot on the break ready to move off the driveway.

Unhelpfully, the manual states that the driver display should tell me which bulb is out but it doesn't say a thing.

I read on the forum that the canbus system is extremely sensitive.

I have therefore replaced every single exterior bulb (that's tail lights, brake lights, indicator bulbs, reversing light, rear fog light, side repeater lights, front side lights, front dipped and front main beam) to absolutely no avail. The only bulbs I haven't been able to replace are the front fog/cornering lamps, because again the manual seens to be wrong and lists the wrong bulb, however both are working. Whilst at it, I checked the contacts and where possible sprayed some contact cleaner on them. There was no corrosion on the rear stop/tail lights.

Please could somebody help identify the issue?

Could it even be as simple as the system not liking the replacement high level brake light?

 

[lar46]

Hi , did you get problem fixed , I have a problem with a 2010 altea xl tdi , have run vcds which showed rear fog bulb , and front fog bulb , replaced all bulbs , now showing same fault codes , did you get any help in here ?

 

[garyRR]

Both tear tail lights had a little corrosion, so I used a little sand paper and contact cleaner. And I suspect the actual reason for the fault was a blown numberplate light.

 

[lar46]

Damn !!!! Number plate lights are only ones not tested yet , just recovering from hip replacement , getting grief from family for even having done what I have done , but this afternoon it is number plate light strip clean , thanks for response

 

[lar46]

Number plate lights in good condition , no corrosion bulbs operating when tested with battery , another non event !!

 

[lar46]

Number plate lights in good condition , no corrosion bulbs operating when tested with battery , another non event !!

Problem resolved , break in feed to/at relay tray , auto spark had problem tracing it as wiring diagrams not totally accurate , but then they seldom are in my opinion. Replaced with alterative feed from main supply via a unused fuse. Instant result an codes gone.
Larry.......old but not done yet !!!