Skip the auto shop - Our mechanics make house calls

Q: Battery/Alternator - 2008 Toyota RAV4

asked by on

One day I noticed a different sound coming from engine. It was a low hum sound. It was not super loud or distinct I just noticed it was unusual. Not long after battery light came. The next few times I would start the car sometime I saw the battery light and heard the noice-others time the car was working as normal (no warning light/noise). I usually drive my car for short distances. 10-15 minutes trips are normal so maybe the battery is not getting enough charge. The car was operating normally and I ran some errands. On my way to my second stop, the power steering dropped out. Many warning lights turned on - such as VSC, battery, check engine, oil light and steering. This leads me to believe it is an issue with the alternator. I parked the car and turned the engine off. The car would not start again. I used a battery jump to recrank car. The car would start but would not stay on. I attempted this a couple of times. There is lots of corrosion on the battery also.

My car has 90000 miles.
My car has an automatic transmission.

A: The battery and charging system should be e...

The battery and charging system should be evaluated first. However, if your battery is more than 5 years old, I would simply replace the battery outright before doing further diagnostics (which are still needed). Batteries are actually critical components of vehicles, even much more so these days due to the proliferation of electronics in vehicles, and the fact that some components are very sensitive to voltage disturbances.

To work properly, the battery has to not only supply the right voltage, but it has to supply enough current to all the devices in your car (ignition, HVAC, lights, etc.) without excessive voltage drop. So you could have an old battery that has problems. But even if you "simply" replace an old battery, the mechanic will check the output of your charging system of which the alternator is just one component. So, initially, yes you appear to have an electrical problem and the initial points of concern are the condition of the battery and whether your charging system is functioning properly.

If you would like to have this resolved, consider YourMechanic, as a certified technician can come to your car’s location to diagnose the charging system and have this problem addressed.

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

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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: Battery discharged in SUV

Hi. If the battery discharged while you were driving, it sounds like you have a charging system problem. The computers that enable the engine to run need the battery, with a charge, to operate. Even with a good alternator, a...

Q: What size tire chains should I use?

Driving in winter conditions in an area with the potential for snowfall means carrying tire chains with you in case of an emergency. However, you need to use the right type of chains for your tire size. Your automaker mandates...

Q: Door & trunk ajar, brake and battery warning lights come on while driving off and on. Alternator tested good & bad.

Hello. Have you had the vehicle scanned for diagnostic troubleshooting codes? You may want to have the vehicle scanned when you receive these warning lights. They may give you more insight to what the computer has detected. If the alternator...

Related articles

Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
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...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.