Help: Fire under the hood

My GF starts panicking thinking the car is about to blow, and i thought it was only water on my brakes, but then it got worse so i parked, pop the hood and saw that a wire and part of the hood was on fire. Used my coat to extinguish it, burning my hand in the process
I have read other threads about S-classes taking on fire, but most of them had to do with the left side of the car (the american driver's side). But the wire i'm talking about is the one right behind the right fuse box (american passenger side) , and i was wondering what is this wire?! If i'm not mistaken there's a SAM under that fuse box, does that wire have anything to do with it? The air compressor is also down there,so does that wire connect the compressor to something?
I'm no expert in electricity, but it looked like a ground to me (two small copper-like wires wrapped in rubber). So why the hell would a ground burn without the fuse blowing first?!
I was going to tape it and keep driving but then i told myself that if it catches on fire again on the highway and i can't see the smoke because of the speed i'd be in more trouble than just paying to get it towed. So i played it safe and waited 3 hours for the towing guy.

Anyway, what is this wire?!
I'll post pictures tomorrow to show what i'm talking about exactly.
Thanks!
Last edited by DNA47; Apr 30, 2014 at 06:23 AM.
In the USA auto insurance comprehensive coverage covers fires, even if they result from a mechanical issue . Don't know the specifics of insurance in your country but check it out
I was just wondering what that wire was! i didn't get the time to really look at it once i got home because it was 3AM, but i remember that my other S500 (without the parking sensors) had a plug coming from the inside of the car (on the right side) with no wire attached to it while my other S500 (the one that got on fire, with parking sensors) had that plug but with a wire. I'll take a look at it this afternoon and see if that's the wire i'm remembering.
But as stated, i'm sure i'm wrong but it realy looked like a ground to me so i'm clueless on why it got on fire. From what i know a ground should protect me from that kind of s*it, not get on fire!
My totaled S500 has the same wire coming from the inside of the car but once out it has a plug that connects to nothing. So I called my local dealership and some guy told me that from the part number provided (168 545 23 28) that "plug" didn't belong in my car and it usually has to do with the fuel pump (but he's wrong since both my S500's had that part).
So i decided to get a second opinion, I called SilverStar Mercedes in Montreal (biggest MB dealership in Canada) and I've learned that this part has to do with an auxiliary blower found only on S65s (Both my cars are MY01, weren't S65 only introduced in 03?).
So on my car (S500), it shouldn't be connected to anything. But it is/was before burning! And it's not some "jobber" that played around with the car, because everything looks OEM (has the same "tape", goes in a big connection of other wires, etc.)
The wire has been now cut and tapped, and every thing in the car still works (played with every little gizmo and everything is still functional).
At first, i thought it had something to do with the parking sensors, but even after completely cutting the wires, the sensors still work.
So what the hell does this wire do? do you have it connected to something? Right now, the car is still being driven with that wire being cut and taped with electrical tape and twisted caps. But i'm still scared that it could burn again since one part of the wire is still "live" and for the next few days i have NO time to take it in and get it looked at. (i know it's stupid, but i need the car and have no time right now!)
Here's some pics of the plug i'm talking about (pictures are from the S500 with the plug connected to nothing, since the one that caught on fire completely melted)
Last edited by DNA47; Apr 30, 2014 at 06:19 AM.
Does anybody have this plug connected to anything on their S500? after some research and looking at a lot of picture, all the one that I see are connected to nothing?
I had this intermittent "rattle" up front... which I sort of lived with and end last year I thought I would lube / service the whole windscreen wiper unit/mechanism. (Good idea to do - many little points / joints to lube!!!)
On removing the entire cast aluminium w'screen wiper unit (very easy to do) - I saw the rattle culprit!
Yes : the same connector had somehow got into the wiper assembly and the wipers in action at some point in time, physically "chopped" this connector off the wiring harness! Connector lying in the bottom area below the screen!!
Likewise, I also could not fathom out what / where / how this connector belonged!
If as stated this connector is for the aux blower unit - all is good and fine, my car doesn't have this aux blower.
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I don't know what it is for, but it is hooked up in my car to a 2-wire cable (fairly heavy gauge brown and black wires) and LEDs down behind they relay/fuse box in front of the air handler, then forward toward the right front fender.
I am unable to see it we'll enough to trace for you at this time.
My car is a 2009 W216 CL600 same connections as the W221 S-class
Last edited by quartey01; Oct 15, 2014 at 01:56 PM. Reason: typo

So the installer of your windshield replacement is probably to blame..
Cheers Frank
Last edited by Frank_S500; Oct 18, 2014 at 06:04 PM.
There is another potential problem here, there is a relay for the heater, and if the relay is bad and the heater is bad, the heater might be kept on, and the fuse would not notice anything bad before the fire starts.
So your idea to pull the fuse could be quite attractive.
Hope the real electric experts pitch in.








