Headlights/DRLs have stopped working

[John Iddles]

Our 2010 T5.1 Cali has suddenly decided that its headlights/DRLs don't want to work any more. VW in their wisdom omitted to include a fuse list in our Cali's handbook (due to ongoing developments apparently!), so I checked all the 15A fuses in the dash and battery-bay fuse-boxes but all are OK. Likewise, the headlight bulbs (which I had always assumed were dual filament since the also act as the DRLs on this model/year, but are in fact only single filament Halogens) were also in perfect condition. The tail-lights and full-beam lights all work as normal. A check with my OBD reader brought up zero snags (I didn't really expect it to log headlight/DRL problems anyway).This leads me to suspect some control unit fault or unknown reconfiguration process which has accidentally been triggered, but again our handbook makes no mention of a DRL defeat function, and as stated above, the headlights have ceased functioning as well.
If anyone out their in Cali-land knows the particular intricacies of the 2010 model and its unusual DRL arrangement, I would be grateful for advice before we trog-off to an auto-electrician to sort.

 

[WelshGas]

Our 2010 T5.1 Cali has suddenly decided that its headlights/DRLs don't want to work any more. VW in their wisdom omitted to include a fuse list in our Cali's handbook (due to ongoing developments apparently!), so I checked all the 15A fuses in the dash and battery-bay fuse-boxes but all are OK. Likewise, the headlight bulbs (which I had always assumed were dual filament since the also act as the DRLs on this model/year, but are in fact only single filament Halogens) were also in perfect condition. The tail-lights and full-beam lights all work as normal. A check with my OBD reader brought up zero snags (I didn't really expect it to log headlight/DRL problems anyway).This leads me to suspect some control unit fault or unknown reconfiguration process which has accidentally been triggered, but again our handbook makes no mention of a DRL defeat function, and as stated above, the headlights have ceased functioning as well.
If anyone out their in Cali-land knows the particular intricacies of the 2010 model and its unusual DRL arrangement, I would be grateful for advice before we trog-off to an auto-electrician to sort.

There are a number of fuses involved with the headlights 30 amp and 5 amp in Fusebox SD, Left side of engine bay near battery. See the pdf file.

 

[John Iddles]

There are a number of fuses involved with the headlights 30 amp and 5 amp in Fusebox SD, Left side of engine bay near battery. See the pdf file.

Much appreciated, I will have another session checking fuses in that box.

 

[tuono001]

Does it show on your dash as a fault?
I recently had a drl bulb failure that pinged on the dash. Initially looking at the bulb I couldn't see the problem, checked the fuse nothing, after further investigation it turned out the bulb glass had worked loose in the fitting. New bulb solved it.
Be interesting to hear what the problem turns out to be.

 

[Abx]

Do you have the standard T5.1 lights or the LED options? If standard its common for the bulbs to go as you always see transporters driving around with one blown, in that case it will likely just be the bulb!

If LED, then I did not have the OE ones but you may want to check the ballast if they are accessable for a loose connection or bad earth.

 

[John Iddles]

Does it show on your dash as a fault?
I recently had a drl bulb failure that pinged on the dash. Initially looking at the bulb I couldn't see the problem, checked the fuse nothing, after further investigation it turned out the bulb glass had worked loose in the fitting. New bulb solved it.
Be interesting to hear what the problem turns out to be.

No alerts at all and nothing on OBD reader. It was only the lack of our DRLs reflection when pulling close to the vehicle in front at traffic lights that I noticed something odd.
Following WelshsGas' pdf, I have just finished checking all the standard sized fuses in the dash and battery bay fuse boxes but are all are OK (visual and digimeter); not sure what the tiny 5A fuses are for.
A further anomaly was we both thought the DRLs used the outer headlight bulb but as I said above, when I removed them yesterday, I found they were single filament halogens. However, the inner lights, which I thought were just the high-beam, look from outside as though they have two filaments so now I'm wondering if they were fulfilling the DRL function. Unfortunately, the inners are far more difficult to get to and check.

 

[Abx]

The inners are the DRL's on standard (non led) lights

 

[John Iddles]

Do you have the standard T5.1 lights or the LED options? If standard its common for the bulbs to go as you always see transporters driving around with one blown, in that case it will likely just be the bulb!

If LED, then I did not have the OE ones but you may want to check the ballast if they are accessable for a loose connection or bad earth.

No LEDs (yet!) but odd that both should go at exactly the same time. What's even more odd, given that the headlights don't work and the DRLs don't work, is the outer lights only have one filament but the inners appear to have two (they are too difficult for me to get to and confirm); full-beam still works!

 

[Abx]

No LEDs (yet!) but odd that both should go at exactly the same time. What's even more odd, given that the headlights don't work and the DRLs don't work, is the outer lights only have one filament but the inners appear to have two (they are too difficult for me to get to and confirm); full-beam still works!

You may find that one going blew them both if on the same circuit, and its been a while as I swapped mine for Led's quite quickly but IIRC the inner DRL's were DRL and main beam/flash, I could be wrong though!

 

[WelshGas]

No LEDs (yet!) but odd that both should go at exactly the same time. What's even more odd, given that the headlights don't work and the DRLs don't work, is the outer lights only have one filament but the inners appear to have two (they are too difficult for me to get to and confirm); full-beam still works!

You may find that one going blew them both if on the same circuit, and its been a while as I swapped mine for Led's quite quickly but IIRC the inner DRL's were DRL and main beam/flash, I could be wrong though!

The Inner bulbs are H15, 55+15w dual filament bulbs for DRL and Main Beam.
The outer are H7, single filament Dipped Beam only.

I‘m not sure if they do trigger a bulb warning light as you have a Dashboard warning for Main Beam/Flash, and normally you know if they are not working unlike some of the other lights.

 

[John Iddles]

You may find that one going blew them both if on the same circuit, and its been a while as I swapped mine for Led's quite quickly but IIRC the inner DRL's were DRL and main beam/flash, I could be wrong though!

Yes, the inner reflectors on ours has the dual filament bulb for DRL and high-beam. No fuses have blown, and no bulbs appear faulty. Both high-beams still work but neither headlight nor DRLs work, hence I'm left scratching my head and can only assume there is a control function fault.

 

[John Iddles]

Update since completeing my checks on fuses and bulbs. Having finally deciding to leave the problem with an auto-electrician, two days later (and £277 lighter of pocket) the snag has been cleared; one £6 lighting relay deep iside the dashboard had failed. Thanks to all those who helped with fuse layouts and suggestions.