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 1,000 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!
  1. Home
  2. Questions
  3. 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: Stalls out when I put in drive p1729

Given your mileage, it is likely the throttle body and idle air controller need cleaning. It is also possible the throttle position sensor (which communicates with the transmission) may also be failing. This would seem more likely since your replacement...

Q: So my windshield wipers get stuck in upright position and won’t go back down what could this be?

The windshield wiper system uses a small electric motor to move the wiper arms that you see on the windshield. That electric motor is controlled through a switch, relay, fuse, and wiring. One, or more, of those electrical components has...

Q: Q: Key not starting car

Another key could be used to see if the lock cylinder will turn completely. Chances are either the lock cylinder itself or the lock cylinder housing is at fault. The may both need to be replaced to restore ignition operation....

Related articles

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...
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...
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...