Q: hi. 2002 mb c240. light came on for visit shop battery/alternator. Battery is new. how to know if alternator is bad?

asked by on

the head lights are not coming on automatic but high beam or manual turn on works. How to check it alternator or voltage regulator? is it better to just change the alternator. The car has about $125K miles.

Hello, thank you for writing in. The alternator can be tested by checking the voltage coming from it while it is running with a voltmeter. You should also check the voltage when revving the engine to 2000 RPMs. The alternator can also be removed and tested at most local automotive parts stores. There should also be a gauge on the dashboard that shows the battery voltage gauge to tell you what the alternator is putting out. You want the output to be 14 volts. The issue with the headlights likely revolves around the fact the vehicle will shut down certain systems to maximize what battery life it has. For more help with testing, contact out service department about scheduling an appointment.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. hi. 2002 mb c240. light came on for visit shop battery/alternator. Battery is new. how to know if alternator is bad?

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Car has knock in the motor and won't start.

It sounds like your engine may be seizing up due to low oil. I would first recommend checking the engine oil to ensure its proper level. If the oil is low this could be your problem. If the engine is...

Q: My car cranks but will cut off shorts after starting up. If i start it up again, it will crank but runs and tries to cut off. 2009 Mercedes Benz C300

Hello. Many different faults will cause your 2009 Mercedes C300 to cut off after starting. The most common would be a fuel pump, fuel filter, battery, alternator, battery cable, crank sensor, or camshaft position sensor. All of these can cause...

Q: Windshield wipers and horn not working

Hello. The first thing to check is all the fuses. If all the fuse are good, a scanner needs to be connected to car to check for code and data. Everything in the column and steering wheel goes through the...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...