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2017 Pilot EX-L - Battery light on, slow cranking, possible alternator failure?

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Kevin B. · rep 0 · May 22, 2:45 AM · 1 replies · solved · Question

Vehicle: 2017 Honda Pilot EX-L

My 2017 Honda Pilot EX-L started showing the battery warning light on the dash a few days ago. Now, it's cranking very slowly, and I'm worried it won't start soon. I had the battery tested at an auto parts store, and they said it was good, but the charging system might be failing.

Could this be the alternator going out? What are the typical signs, and is it something I can check myself before taking it to a shop? I don't want to get stranded, especially with family in the car.

Any advice on confirming an alternator issue would be greatly appreciated.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 2:45 AM

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ClearTheCode admin answer:

Your symptoms—battery light on, slow cranking, and a good battery test—strongly suggest an issue with your charging system, most likely the alternator. The alternator is responsible for generating electricity to power your vehicle's electrical systems and recharge the battery while the engine is running.

1. Symptoms of Alternator Failure:

  • Battery Warning Light: This is the most direct indicator.
  • Dimming Lights: Headlights, dash lights, or interior lights may dim, especially at idle.
  • Slow or No Cranking: The battery isn't getting recharged, so it eventually runs out of power.
  • Electrical Component Malfunctions: Power windows, radio, or other accessories may work erratically or not at all.
  • Strange Noises: A grinding or whining noise can indicate a failing bearing within the alternator.

2. Basic Alternator Test (with a Multimeter):

  • Engine Off: Check your battery voltage. It should be around 12.6 volts.
  • Engine On: Start the car. With the engine running, check the battery voltage again. It should now be between 13.5 and 14.7 volts. If it's still around 12.0-12.6V or lower, your alternator is likely not charging.
  • Load Test (Engine On): Turn on headlights, radio, and AC. The voltage should remain above 13.0V. A significant drop indicates a weak or failing alternator.

3. Common Causes:

  • Worn Brushes/Bearings: Internal components wear out over time.
  • Voltage Regulator Failure: The regulator controls the output voltage; if it fails, the alternator can overcharge or undercharge.
  • Damaged Rectifier: Converts AC to DC power; failure leads to insufficient charging.

When to See a Shop:

  • If your multimeter test confirms low charging voltage, your alternator needs replacement. This is not a repair to delay, as your vehicle will eventually die completely, leaving you stranded. A shop can confirm the diagnosis, check for related OBD codes (like P0562 - System Voltage Low or P0563 - System Voltage High), and replace the alternator safely and correctly. Driving with a failing alternator can also strain other electrical components.
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