Reversing Light Bulb

[tc4332]

I'll defo be in London 11, 12 & 13 November for the Cenotaph march past.
We are trying the Barking Premier this year.

[Turbo Tony]

Err...?

[tc4332]

Sorry Tony,
I screwed up.
That was supposed to be an email reply to someone else.
I'm getting too old for this stuff, need to be put out to grass!!!

[David's8]

Gives a new meaning to "Senior Member"

[tc4332]

Nice one.
I like it.
As I've said before, this forum is the best.

[Turbo Tony]

OK, so I bought those lights off eBay and I'm now considering how to fit them.

Although it's not really shown in the pictures, the bulbs come with resistors on a fly lead. The fly lead has a plug, so they're easily removed if not required.

This got me thinking. Rather than have to manufacture a way to fit the resistors, is it possible to use VCDS to tell the car not to check the reverse bulbs for errors?

If it is, I could simply plug in the LEDs, tape off the plugs and I'd be done.

Anyone delved enough into VCDS to know? The VAG COM forum seems to say it's possible on a Passat, but details were sketchy.

[Turbo Tony]

OK, so I did a little experimenting tonight with the old and new bulbs. Sadly, I couldn't do it on the car because it's pitch black and raining at the moment. I jerry-rigged a battery charger as a mock power source and I had an old tail-light that I opened up. Here are my findings:

1. The LED is brighter than the halogen, but the light from it isn't dramatically different. I'm hoping it's that nice blend of modernising without the after-blindness.
   
   
2. In less than 20 seconds, the factory halogen bulb got so hot that I burnt my finger on it by touching it by accident (it's still stinging now!). The casing for the resistor for the LED took around 5-7mins to get to the borderline between warm and hot. I could still hold it comfortably at this point, so I'm not worried about heat damage anymore - after all, for how long does anyone engage reverse gear?
   
   
3. I found a nice little slot next to the rear fog lamp bulb that will fit the resistor perfectly. Installing it in this location will mean removing the fog lamp bulb and refitting it but it does fit quite nicely. It's basically right next to the cable entry point.

I've uploaded a few pictures of my experiment below. Hopefully someone finds them useful.


Here's the LED bulb (left) and the OEM halogen bulb (right).



These are the two bulbs beside each other, with the LED resistor.



The difference is there but not crazy big.



Here's the same shot but at a different camera setting, which shows the LED is emitting more light than the halogen.

[ainarssems]

Does it even trigger error without resistor for reverse bulb? I would avoid using resistor if posible. Halogen lights reach max temp very quickly and and stay there. Resistor will keep building up temp for a long time. Not really a problem for reversing light as it is only on for short periods of time but I woulld still avoid resistors unless absolutely necessary.

[snapdragon]

I needed 2 resistors as per post 25 otherwise the resersing lamps get disabled after a minute or so, even if they have not been used - the resistors got very hot and I wouldn't want them in the cluster, they would melt plastic for sure.
They are mounted on part of the internal structure of the aluminium boot lid.

[tc4332]

Rather than resistors I would use a low watage bulb in parallel with each of the LEDs. These would let the monitoring system think that each light circuit was poroperly loaded so not triggering the failed bulb alarm.
A low wattage bulb would become hot but not as hot as the loading resistors, and there would possibly be more light generated. My main problem with my reversing lights is that they do not produce enough light.
If only they made "dark suckers" that worked more efficiently