Grrr modern cars bah

[Yugguy]

Got some nice bright white leds for my sides, canbus compatible, others have used them in w204 c-classes.

I'm old school so I do what I've always done, switch the lights on and so I can see when the new bulbs works.

Here's what I did.

Undid the inner drivers side cover and pulled out the bulb holder with pliers. Bulb is on at this point. I take it out and try an led. No light. Try the led the other way round, no light. I try the other leds. No light.
So I go to put the original bulb back in but it has blown. I try several other normal wegde bulbs but no light.
I check the bulb holder metal strips and bend them tight. I even connect the metal loop wires on the bulb to the wires going into the holder but no light.
All other lights are fine.

So at this point I am wondering what on earth so I post on the Merc forums:
Is there an inline fuse somewhere? Have I made a mistake changing the bulb with the lights on? Has the car somehow decided not to send power to it?

And yes, it turns out that if the car detects a failed bulb it cuts power to the circuit and will not restore unless the lights are switched off completely and the bulb replaced with a working one.

Stupid clever modern cars bah rubbish.

 

[HDi fun]

Put a DVM across the terminals. If you can scrounge a 'scope even better. I do agree though that you shouldn't need laboratory equipment to change a bloody tungsten lamp !!

 

[Yugguy]

Aye - once I realised I needed to completely switch off the system I was able to put some standard wedges in that will do til the weekend.

The leds should work although as they need the correct polarity I will have to swap with the system off, the switch on the lights, then if any don't work I will need to switch the system off again, rotate the leds, then switch on again to check.

Awesome. Not.

The car is very nice but there is one quite glaring omission I feel. Unless you order the rear ashtray option you don't get a power socket in the rear. I looked at buying one but they are like 70 or 80 quid even secondhand, ridiculous, so I'm going to buy this:
http://www.ebay.co.uk/itm/252287890988
and mount it in the blanking plate where the ashtray would be, using the power wire that's there already but not used.

 

[obi_waynne]

It's never easy! LED bulbs just draw so little current it doesn't flag up as a live bulb!

 

[HDi fun]

But as LEDs replace incandescent ones at the factory this will no longer be a problem. In fact, the need for lamp failure monitoring will diminish due to LEDs' long service life. It's a shame to criticise LEDs for their inherent efficiency.

 

[Yugguy]

Managed to change them, it looks good now.

 

[HDi fun]

Nice work!!

 

[T9 man]

Excellent Guy, I see you are pleased with your handy work?

 

[Yugguy]

Nighttime pics