Just thought I would run this by all of you because it really scared me!

2004 E500 180K miles (UK)

I've had it just over 2 years it's been great. All problems have been over come, I've just got it's second service done (E).

Last week my remote fob stopped.
* The key-less entry was still working, but it's only ever partially worked on my car so I rely on the fob
* I started using the infrared entry which was ok but wanted to fix it
* First result on youtube took me straight to a dead fuse.


On Sunday I replaced the fuse with an identical one
* Shortly after I smelt a strange smell that was like the cap guns we used to have as kids (similar to matches).
* I was looking around but could't see anything obvious.
* My fob was now working..major win (or so I thought)...

I started seeing things in my peripheral vision which didn't take long to realise was smoke.... which got blacker and blacker...
I raced inside the house and yelled for assistance "Have we got a fire extinguisher?".... the answer I was fairly sure was no but instead I got was "I'll get water" ..... "Nooooooo" (being a very obviously electrical fire)
I luckily had my tool kit near by... emptied everything from the boot (it's an estate so it's always full of stuff) straight in to the road.... The smoke and turned in to flames by now which was not good...
I got the battery disconnected and removed the fuse as well... at which point the alarm starts going off. my partner and I rip off the panel (which doesn't appear to be easily removable) and blow out the flames on that then tamp out the fire on the wires....
Panic over but seriously shook up....

The location was driver side (UK) rear boot internal liner (so the other side to the one with the first aid kit)

I've contacted insurance and think they'll probably 'write it off' but just thought I'd get thoughts on the matter as I've had plenty of old cars but never anything like that....

Still want to stick with a Benz but I'm definitely going to get a fire-extinguisher.
Not that it would have helped as without the battery disconnected that fire would have kept going and I'm sure burned it to the ground....

I now think all cars have an electrical kill switch... very scary!

 

You have lot of stuff packed behind the liner.
Will wait for the picture what actually was it.
Good you saved the car.

 

What's the best way to upload pictures these days?

Thanks,

 

Pictures below.
Apologies for the image size:
The fire seems to have actually started from the wires directly below the melted plastic bracket (I'm guess the black wire as the red still look in good condition)
I guess the green Shield Bug likes the smell of burnt plastic (I didn't want to keep it in the house)...

 

Hi Jteez,

You wrote :
On Sunday I replaced the fuse with an identical one
* Shortly after I smelt a strange smell that was like the cap guns we used to have as kids (similar to matches).

I think the fuse you bought is bad, as in its rating is higher than what is actually stamped on it.
You never know now with so much parts coming from China and the rating maybe off by much.

You wrote :
* I was looking around but could't see anything obvious.
* My fob was now working..major win (or so I thought)...

Now, if the fob works again with new fuse installed, the initial fuse blow most likely was not caused by the module which controls the fob receiver, but most probably there was a wire jacket damaged and it short circuited the original fuse to ground.

If the new fuse you installed, assumed a 30 amps one even though the label is probably 7.5 amps, and looking at the small wires being used, it may cause that wire to burn ( because there is still a short circuit ),
...or....wire got hot enough to burn other things first touching the hot wires.

If the new fuse you use is an exact same rating (as in true rating), it will very most likely blow again and not cause that fire.

Anyway stay safe.

 

Thanks for the reply!

I agree with you... I'll take the fuse to work and test i at what point it blows...

Thanks,

 

Go to page 7 of this file https://www.mouser.com/ds/2/240/afte...032-245493.pdf , you will see the time current "blow" curve of ATO fuse, or if this is an MCB it will be the tripping curve.
Happy troubleshooting

 

Perfect thanks!

I was just out there and noticed something else interesting... The thing I thought was a black cable (above the two red ones)... Isn't a cable, it looks like the rear screen wash. Just out of view there is a checked valve that's disconnected. Perhaps got blocked, and blew it's self off, then, given where it is sprayed the back of the connector to the module which shorted the wires and when the fuse didn't blow got hot and caught fire.

Looks like the 5A fuse should blow in about 10 seconds with 6.5A. Will hopefully get to test it on Tuesday.

Thanks,

 

Hi Jteez,
I don't think water is the cause, because fresh water itself is not very conducting for electric to a point of producing fire that fast.
Also water on a cable with PVC jacket intact, will do no harm...assuming fuse box module is dry and only cables get sprayed.
If water sprayed to the fuse box module, which is also a SAM module....check for water trace and make sure all connection dry using air pressure before you re-connect all batteries.
Your car has two batteries right ?