Willis

Have a 2003 C32 with 94k, regularly maintained. Was driving home from work recently and while sitting at a stoplight the thing totally dies. Absolute electrical failure (hazards, everything). Get it towed to my local shop, and when they take a look at the car the next morning, it starts right up. No codes to pull. One of my xenon igniters had been going bad so I had them replace it while it was there, but they then proceeded to spend a week trying to figure out what could have caused the sudden failure and couldn't replicate it. Has driven fine now for a few weeks without any sign of issue.

Any thoughts/suggestions would be greatly appreciated. Thanks!

Tump43

Willis, there's only a couple of things that can do this -- total battary failure or total alternator failure -- barrring any kind break in the wiring harness, loose battery terminal leads, or short in the ECU. Most likely, if not the batttery or other items, it is the voltage regulator under the plastic cover on the back of the alternator. This part is pretty cheap -- 20-40 bucks -- and can usually be replaced without removing the alternator. Besides the battery and alternator itself (which can be easily tested), the voltage regulator is a notorious wear item and it seems possible that it could work intermitantly as it's on its way out. It should be replaced every 80k miles or so.

Willis

Hey, thanks a ton for the reply. I had the battery and alternator replaced about 4 years ago but I'm wondering if the old voltage regulator is still on there. Will look in that direction.

insame1

I dont know if the VR on the c32 is serviceable. I have one at home though ill check.

Willis

Part number they installed for the new alternator was 011154910288.

Tump43

Batteries generally need to be replaced every 2-4 years depending on the battery, mileage and use. Don't know about part numbers, but the VR has two spring loaded carbon fingers that ride against the alternator's rotor. It's these fingers that wear down (like brake pads), loose contact and render the alternator unable to charge the battery at all or quickly enough.

RLx02

I had the same issue on my c55 and it was the voltage regulator.

blackberg

My sister has a w208, she had to get towed home one day, turned out the grounds underneath the motor that attach tot the body had become frayed, one was off completely, the other was only on by a couple of threats, was able to resolder new ends on them and re attach to the body and all was well
-bb

Willis

In case anyone looks this up in the future, it was just a bad battery. Swapped it out and the car has been perfect ever since.