Skip the auto shop - Our mechanics make house calls

Q: Battery light coming on faintly after installing new alternator

asked by on

Changed my alternator yesterday, the battery light keeps coming on lightly. It gets brighter as I accelerate. Headlights dont dim when I rev the engine though.

My car has 237000 miles.
My car has an automatic transmission.

Hi there. Have you had the battery tested? Use a digital battery tester that provides current voltage, cold cranking amps, and state of health. Any corrosion on the terminals? This could present an opportunity for electrical disturbances and create concerns. However, this does sound like the alternator or belt is at fault. Check for proper belt tension and belt condition to ensure that it is not slipping. If it is slipping, then adjust/replace as necessary. If this checks ok, then the alternator may be at fault. Even new parts can be faulty and a proper load test will uncover whether or not it is indeed faulty. When you rev the engine, the alternator spins accordingly and can provide additional voltage/amperage which is probably why the light starts out dim and gets brighter when you do this. I suggest having a qualified technician perform an inspection to avoid replacing unnecessary parts. Your Mechanic has several available technicians that can assist you with a charging system inspection.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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: Engine misfire on all cylinders

The actual codes would be needed to steer you in a precise direction. Generally, global misfires are a consequence of a major fuel and/or air induction system issue. Your vehicle has individual spark plug coils so that is not likely...

Q: AC is not cold

A ten year old car is very likely to have lost some of its refrigerant charge. Even if the system has no detectable leaks, Tiny amounts of refrigerant can leak past the seals and over time you will lose enough...

Q: My turn signals don't flash when I signal them.

Hello. Thank you for writing in. Yes the flasher is most likely your issue. It is luckily a very simple fix. The lack of clicking noise, but supply of power, tells us that the flasher is stuck in the on...

Related articles

What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
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...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.