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. :)

Your Answer

Add photo

Related Questions

  • rough idle, stalls 1 answer

    idle intermittently rough, stalls at lights

    2010 Ford Escape XLT 4WD


    Maintenance & Repair

  • Dimming lights on 06 Trailblazer 5 answers

    Lights dimming (dimmer/brighter) when engine is idling. Does anyone else have this problem? I've been told it's "one of those things" I have to live with on an 06 Trailblazer. Already changed the a...

    2006 Chevrolet TrailBlazer


    Maintenance & Repair

  • Rough idle 5 answers

    I just bought a used 2012 Chevy Colorado the inline 4 cylinder LT. The truck has a rough idle we scanned it because the CEL has been on for misfires in cylinder 2. I got it through a dealer and w...

    2012 Chevrolet Colorado LT1 Crew Cab


    Maintenance & Repair

  • Rough Idle 4 answers

    I have a 2008 Nitro At stop signs it will rough idle and lurch forward.Need info

    2008 Dodge Nitro


    Maintenance & Repair


Search Maintenance & Repair Questions

Maintenance & Repair Experts

#1 Tom Demyan
Tom Demyan
Reputation 168,420
#2 dandyoun
Reputation 91,450
#3 tenspeed
Reputation 73,800
View All

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.