Rough Idle with dimming lights?

Asked by Nov 25, 2013 at 10:24 PM

Question type: Maintenance & Repair

Hi! I have a Mercedes c class 230...2004. My car has a rough idle, and when it does the
lights seem to go bright n then dim. It hasn't stopped but I am a single mother who knows
nothing about cars, and get taken advantage of alot. So I would REALLY like some advice
on an effective but inexpensive way to repair my car. HELP!!!

1 Answer


Sounds to me like you have a failing alternator. The alternator is nothing more than an electrical generator. Without it nothing will run once it has completely failed. Take a look at your battery or voltage gauge and notice the voltage will be variable up and down etc. your lights can dim your idle can slow and if you do not replace it soon the car will simply quit in some random location. I would try to find a good friend or someone who knows how to remove the alternator and simply replace it. Should solve the problem. I have replaced alternators in 3 types of vehicles, a Pontiac Vibe, BMW 528E and two Ford Bronco's. The work is relatively easy if the alternator is up high and easy to gain access to. Some alternators are easily removed by simply lifting the belt tensioner, sliding the belt off of the pulley, disconnecting the plug in the back and removing the mounting bolts. Mercedes alternators are rather expensive but good quality. You would probably save a lot of money by having a handy friend do the removal and replacement as long as you purchase the alternator separately. Dealerships charge an arm and a leg for this type of normally simple replacement. Find the part and have a friend replace it. Hope this helps. :)

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