Hardwiring W216 / W221 - Negative Terminal?

[sunnydude959]

Hi Guys,

I'm trying to hardwire a GPS camera location alert device (Cheetah C550) to my left hand side fuse box on my W216 CL500.

I have done it as follows;



but it doesn't work. I suspect that its not getting an earth from the panel I have attached the black lead to;




I wonder if anyone on here has experience of hard wiring something to the CL or S class' fusebox, and how they got around this?

Is there anyway to check for 'earth' using a multimeter? I've got one but have very little experience using it.

(N.B. Those cables have been properly crimped underneath the electrical tape!)

Thanks
Sunny

 

[renault12ts]

Anywhere on the chassis is an earth...are you sure that screw screws into metal?

 

[markmifsud]

just get your volt meter, secure the red wire to your power feed, then probe the available screw points with the black cable and see where it registers a decent 12+ volts

 

[sunnydude959]

It seems to sound like metal if I tap it, but its not getting a connection. I even sanded it down slightly to try to see if I can get beyond the paint, and I think I did (its still sort of greyish), but still no connection. It might not be connected to chassis even if it is metal.

The other screws don't seem to be earth either :/

It just seems odd that theres no earth near the fuse box. People can and do hardwire things, and this just seems really silly.

 

[sunnydude959]

I've just seen this;

Added A Hardwired WiFi Hotspot - MBWorld.org Forums

He's used the same hole that I have and it's working for him!!! :/

 

[RichardF]

That looks like a coach bolt you're trying to hook up too! Maybe not enough thread are you sure it's tapping into the chassis?

Just poke around with your meter till you find a decent earth.

 

[sunnydude959]

OK So i've found a good earth;

Its one of the bolts that are already there, sort of more to the left of where I tried previously. I used the resistance method by putting the + probe of the multimeter to the negative terminal of the battery, and poked around using the - probe of the multimeter to find a point with low resistance, i.e. earth.

However, my device still doesn't work and all the fuses are intact. I feel that it may be a bad wire :/ - I'll have to do more multimeter tests!

Thanks for your help guys

Sunny

 

[sunnydude959]

Right, I've sorted it. Turns out that I did a really bad job at crimping the live to the double fuse socket. Fully working now.

Thanks for your help