mleads310

Good afternoon everyone, just picked up an 08 CLK350 for my wife. Having an issue with the drivers side head light wires.

There's no power/signal going to the parking light/daytime light pin out on the plug. Driver's side color on the plug is gray/black. I'm assuming there's a pinch in the wire somewhere or a clear break, but I'm having a hard time tracking it back towards the fire wall. It appears it may run under or along the fuse box in the engine compartment and then I'm lost.

My question is from the plug/pin out going back towards the firewall where exactly does this wire end up? Where would the next connection be for this wire? Any help is appreciated before I start tearing things apart.

Thanks again

Diamond Dave

Welcome to the club!! The Mercedes learning curve can be steep for sure. I was in a similar situation where I couldn't get my driver HID to turn on. Looked for fuses. There were none. Replaced the bulb. Nothing. Replaced the ballast. Nothing. Turns out I had to replace the entire front SAM (signal acquisition module) - the fusebox. Bought a used one on eBay and carefully removed all the harnesses. Easier than you would think. YOu'll need to do more research and learning, but it's more likely to be the front SAM than anything since water is prone to dripping onto it.

I have more detail in my project here: https://mbworld.org/forums/clk-class...ml#post8766389

mleads310

Hey Dave, I really appreciate the quick response and I suspect that you are correct. I guess the next thing to do is watch the video on how to remove the Sam, get the part number and order one on eBay. I also read through the rest of your thread on your repairs and some of them may come in handy as I believe I need front control arms on this car along with rear shocks. Again, I can't thank you enough for responding so fast.

Thanks
Mike

g0rsq

Diagnosing light issues can be very complicated due to the way the electronics work!

When everything is working fine, a known amperage is going to the bulb, and this is measured in the SAM.

If this amperage is too high, then the SAM detects this and turns OFF the output for the light, switches ON an substitute bulb, and puts a display on the dashboard. This prevents damage due to a short circuit.

If the amperage is too low, the SAM also detects this, and turns OFF the output for the light, switches ON an substitute bulb, and puts a display on the dashboard. This is for a blown bulb, or damaged wiring.

So in both cases the output from the SAM is turned OFF for an open or short circuit fault, so you cant diagnose the output with a volt meter!

What you need to do is connect a resistor between the output terminal of the SAM and ground (to simulate a bulb) then see if the SAM output turns ON correctly. The value of the resistor varies, but you can work it out from Ohms Law (remember in school :-) ) (5W bulb is about 30 ohms)

Only then can you start diagnosing with a volt meter.

Diamond Dave

Happy to help. I will admit that I was ho hum about the car even after replacing all the control arms and shocks, but when I got brand new tires and an alignment, the difference in driving quality and confidence was astonishing. Now I get what the fuss was about when these came out.