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 won't start - 2004 Mercedes Benz C240

This maybe caused by a variety of potential issues. For starters, I would suggest testing the key a few times while moving the steering wheel to see if this will get it to start again. Try another key, too, if...

Q: I have a leak in the front left side of my 2002 hyundai santa fe

What you are describing sounds like it could be a transmission fluid leak. I would suggest having the leak inspected and, if a repair is required, the mechanic can implement the repair right then and there. The service to request...

Q: Gear slipping 1st 2nd

Hello there, thank you for asking about your 2010 Mercedes-Benz C63 AMG. The first thing to check would be the transmission fluid level. A low transmission fluid level from a leak can cause symptoms where the engine speed rises without...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
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...