a couple of issues

[Iain_R]

Hi all,

2010 pre facelift ex-BG SDI
A couple of issues I would like some advice on.

Dim tail lights - both my tail lights are seriously dim. I have removed one of the bulbs to check for dirty contacts at the bulb but all looks good. It doesn't seem to affect the other bulbs, however they are higher wattage so it is difficult to be certain. the filaments in my tail lights are barely glowing though. If it was all of the bulbs I would be checking the earth point for the tail-lights (if I knew where it was) but it seems to be just the tail lights which is strange.

The next I suspect may be a tank fuel pump issue. Once the fuel gauge gets to 1/4 tank the van can be a bit hesitant to start when cold. For there, if I continue to drive without filling the tank, the idle gets lumpy and starting gets more difficult. I expect this is a weak fuel tank pump but best to confirm before I drop the tank and replace the pump. Is there anything else that might cause this?

Cheers

[BenT]

You could try replacing the rear bulbs with some others - perhaps the previous owner put the wrong ones in? I think these are dual filament type bulbs, one for the brake light and one for the tail light. If so, it might be affected by the brake light system somehow too if there's something wrong with that.

Do you hear a humming noise for a second or two when you turn the ignition on? If not then maybe the in-tank pump isn't operating (could be a dodgy fuse, or the pump itself). Or, it could be an injector seal issue. Have you checked the engine oil lately and is it rising? If so then the seals might be letting fuel leak past and into the cylinder head rather than maintaining the correct pressure at the injector inlets.

[Nicklouse]

The first thing I would be doing is to check that you are getting 12v to the socket. And then that the socket earth is good.

[Bahnstormer]

I'm sure I remember seeing something on here about tail light dimming in VCDS, do they only dim if the engine is running?

[Doc]

Can you quantity the "dimness" of the lights?
If you were to take a photo on a dark night, can you see the tail lights are on from 30M away?
Do the turn signals and brakes light up to a level you'd expect of these lights?

[Iain_R]

Turn signals, reverse lights, brake lights all as expected. It's just the tail lamps that are very dim - with the bulb holder removed from the lens unit the bulb filaments glow an orange colour. On a dark night you can just about see the lamps but the number plate lamps are definitely brighter.
I have checked the connections and tried new bulbs but no improvement. What did help was fitting LED bulbs, at least it helped for 5 seconds until the control module flashed up a bulb warning lamp and killed the power.

[Iain_R]

Still not got to the bottom of the issue with the tail lights, but I have at least found a work around.

Following the instructions for the MK4 light install, I have coded my brake light bulbs to come on at 25% with the tail lights. I'm using FVAG rather than VCDS so not al of the parameters are detailed on the screen but was able to select byte 09 and input the setting.

It wouldn't surprise me if the tail lights are also controlled by coding but since I don't know which parameter to change I will leave it for now. Maybe on a warmer day I will try to adjust some the other parameters and see if they make a difference.

Next job will probably be to investigate the fuel tank pump, but for now I am just filling up once it drops to 1/4 tank.

[BenT]

I know it's a simple suggestion, but have you checked the voltage at the rear light fittings? It sounds like you might have a current drain somewhere. I wonder if this is linked to your in-tank pump issue...

Does the van have stock headlights? What happens to the rear lights if you disconnect them? Just in case they're somehow draining power.

[Handyandy]

@iain it could be a bad earth connection either from the tail lights or somewhere else

[Iain_R]

I have std pre-facelift Mk3 lights. Bulbs have been replaced just in case but no difference there.

My first thought was a bad earth but, with all other lights functioning as normal, that isn't the case. It's not related to the headlights either as they are on a different circuit. On an older vehicle it could be related to the sidelights, but with all of the circuits individually controlled by the body control module there is very little chance of another circuit affecting both bulbs. (When I tried an LED tail light bulb, the BCM only cut the power to the side with the LED bulb and left the other side switched on.)

Which brings me back to something coded into the BCM, which was sourced from eBay after my original module developed a fault and kept cutting out one of the headlights. It has an identical part number but I believe the module was originally from an A3.

[Doc]

If you have not coded the module, you might find that is your problem.

[Iain_R]

#Doc I thought I had copied all of the original codes across but may have missed one. Any suggestions on which byte needs to be changed for the tail lights?

[Doc]

Not off the top of my head.
If it were me, I'd copy and past the complete coding from the old module onto the new as there will almost certainly be some bits where Ross-Tech have not decrypted the coding or made it available.