Skip the auto shop - Our mechanics make house calls

Q: Alternator not charging

asked by on

I've replaced the alternator twice and the battery as well as the connector to the alternator but it still won't charge

My car has 171000 miles.
My car has an automatic transmission.

A: The alternator charging rate is controlled ...

The alternator charging rate is controlled by the engine control module under the air cleaner housing. You should disconnect the battery and check the connections at the engine control module and look at pin 54 on connector one (C1). It is a grey wire that goes to the alternator to control charge rate. Put dielectric lube on connections and reinstall to see if vehicle charges normal at 1200 RPMs. If not, then have vehicle scanned to see if ECM is controlling charge rate. If you are still having trouble, a certified mechanic, such as one from YourMechanic, can come to your car’s location to diagnose your vehicle’s charging issue.

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: Car doesn't start after replacing key cylinder.

It sounds like you could have a faulty ignition switch. I would recommend getting a technician to test the switch to see if it is working correctly or if it needs to be replaced.

Q: Truck starting

This may suggest a failing voltage regulator. The voltage regulator is a unit that regulates the charging of the battery by the alternator. When the voltage regulator is not working properly, this may result in the alternator allowing too much...

Q: Strange sound in the engine

There should be a vacuum coming from the oil fill hole with the engine running. This is because vacuum is created inside the engine as the piston moves downward in the cylinder. Also, you should feel vacuum when holding your...

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...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
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.