Skip the auto shop - Our mechanics make house calls

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

asked by on

Head lights go dim when all warning lights come on. Stopped at gas station. Car wouldn't start. Battery was dead. Battery tested good. Alternator tested bad at autozone but good at advanced auto. Can an alternator "not charge" intermittently?

My car has 225000 miles.
My car has an automatic transmission.

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 tested bad even once, you should replace it. It is possible to get a false negative and a false positive on those tests. You may want to have it tested a third time by a technician. They do not use automated machines, but use a voltmeter and test it on the vehicle. Typically if the alternator works intermittently then the wiring connections are not solid. Check the vehicle’s connections and make sure they are clean, dry, and tight. A faulty battery can also cause these issues. Retest the alternator and the battery, and instead of bench testing them, have them tested in the vehicle.

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!
  • Home
  • Questions
  • Door & trunk ajar, brake and battery warning lights come on while driving off and on. Alternator tested good & 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: I was stopped at a redlight and I went to go and I pushed the gas but it wouldn't go, so I pulled onto the side of the road and my

Since this is a Hybrid then you may have a problem with the brake pedal switch or throttle sensor. I would recommend having the system scanned for codes to see if there is any stored codes to check. Since the...

Q: Loud screaming behind engine manifold

Since this noise only occurs in first and second gear and does not happen in any other speed ranges, it is most likely tied to an internal issue in the transaxle. All of the other rotating items such as motor...

Q: I am having problems with my car overheating when the AC is on and I'm not driving. No problem while driving. Help please!

Hi there. This might be an issue caused by two possible sources. First, it's possible that your thermostat is not working correctly or opening later than it should. Second, it is also possible that you have an obstruction of coolant...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
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...
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.