Light switch burnt car doesn't turn off
 

Recently I drove away and started to smell some burned plastic wire. Stopped to check outside but could not get my finger on it. Later noticed that switching highbeam raised light level but could not get the lights out.
Lowbeam lights did switch on/off. At destination, ignition did not turn of the car, had to open hood and pull rcm and even battery.
Later that night connected batt. and rcm and could drive away, high beam lights can't switch off, low beam would,
Pulling multifunction increases high beam light level and indicator (indicator is on all the time
All along burnt smell.
At home could only get her out disconnecting battery.
CC roadster..

Today I opened the fusebox and found below.

What would cause this?
https://cimg6.ibsrv.net/gimg/www.cro...54dea92c6e.jpg
burnt power connector headlight switch


https://cimg5.ibsrv.net/gimg/www.cro...20d4f03abc.jpg
different focus on the connector to headlight switch

It's even worse, the pink one melted too...

Re: Light switch burnt car doesn't turn off
 

i recall one time having a customer come in with a headlamp switch that had a internal short. i replaced the headlamp switch and it was fixed. their connector was not damaged like your though but the switch housing was melted and burnt.

Re: Light switch burnt car doesn't turn off
 

THis is the most interesting electrical failure in one of these cars I've heard about - and I've been an owner for almost ten years now.

So, what you are saying is that something failed such that power is still fed to:

• The ECM via the engine control relay.
• The Fuel Pump via the fuel pump relay.

Who knows what else. I"m having a hard time seeing how the light switch could lead to this. But I do wonder about the security pump/module.
I'd yank the trim from the trunk area and look for moisture/water in there. Then I'd grab the service manual and try to find the connection here - I tried, but I dont see it.

This is a good one.

Re: Light switch burnt car doesn't turn off
 

https://cimg8.ibsrv.net/gimg/www.cro...e62844298c.jpg

This shows how bad it is.
I measure a short between VBAT and VSWITCH so this must have caused the motor to keep running.
I can't imagine the RCM playing a role here, but maybe a sticky contact there caused current to jump on a weak spot like this switch.

Now getting a replacement is a challenge. I need connectors and A 193 545 03 04 (the A 1935450004 is for US with 12 fuses) the 0504 is RHD
Mercedes part A1705450104 is confirmed to work but may signal a lamp warning on reverse (from german forum)

Inside of the light switch

Re: Light switch burnt car doesn't turn off
 

I hate to say it, but a salvadge yard is probably the way to go.
That, or go on Facebook to any one of the MANY Crossfire owner's page and buy one from someone parting a car out.

There ARE multiple switched A+ and B+ feeds to the ICM, I suppose it IS possible the ICM could have failed in such a way to make this happen.

Re: Light switch burnt car doesn't turn off
 

The MB part is ordered , used, with connectors, CF part is hard or expensive to come by.
Fingers crossed this will solve it.

Re: Light switch burnt car doesn't turn off
 

It will be interesting to see where this goes.

Please come back and tell us how things turned out.

Re: Light switch burnt car doesn't turn off
 

Re: Light switch burnt car doesn't turn off
 

Re: Light switch burnt car doesn't turn off
 

Yeah saw some on ebay, but the europe ones are slightly different.

I did a quick test pushing the molten connectors in the replacement mercedes part.
First look is good.!!!
On reverse the light for a bad reverse backup indicator comes up..

And I would like to see someones dash on low beam, does it show a default indicator on the dash or not? (Mine not currently) High beam does show blue.
The lights work, and the car works, now all I need is a warm garage or outside weather to do a full reinstall.

Re: Light switch burnt car doesn't turn off
 

There is no indicator for low beam on.