Check charging system

[SimonP]

Two questions about my 2015 Mustang Ecoboost premium:

what activity triggers the ‘check charging system’ alarm ?

does this car have a smart charging system? My voltage meter seems to fluctuate between just over 12 V. And around 14 volts. Would have expected a constant 14 volts if alternator was working properly.

Symptom - ‘Check charging system has come on twice in last few weeks. Each time I put battery on charge as it was low. I the. Noticed the fluctuations in the digital voltmeter reading on dash whilst driving.

alternator changed in around 2017 by dealer under warranty. Battery last changed in January 2024 ( about 4th one I have had !!)

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[CrackedHorn]

Your alternator is likely bad. The idiot light is usually either triggered by a low voltage situation or a big swing in charging. At least in most cars.


A weak battery can also cause similar issues bc it "overworks" the alternator. So can bad/loose cables.

 

[ORRadtech]

First step is don't rely on the dash Guage for voltage. Use/get a DVOM and measure at the battery. It should be in the 14.2v area running.
Next step is to inspect the battery connections and all other connections (alternator, starter, major grounds for tightness and green crusties.
Next step is charge the battery completely and have it load tested. Most auto parts stores will do it for free.

Also, put a scan tool on the car to see if it has any codes.

 

[Torched10]

First step is don't rely on the dash Guage for voltage. Use/get a DVOM and measure at the battery. It should be in the 14.2v area running.
Next step is to inspect the battery connections and all other connections (alternator, starter, major grounds for tightness and green crusties.
Next step is charge the battery completely and have it load tested. Most auto parts stores will do it for free.

Don't use the









Also, put a scan tool on the car to see if it has any codes.

First step is don't rely on the dash Guage for voltage. Use/get a DVOM and measure at the battery. It should be in the 14.2v area running.
Next step is to inspect the battery connections and all other connections (alternator, starter, major grounds for tightness and green crusties.
Next step is charge the battery completely and have it load tested. Most auto parts stores will do it for free.

Also, put a scan tool on the car to see if it has any codes.

Don't use the voltmeter on dash
Just check alternator as noted it shoukd be over 14my 2019 dash runs between 14 and 12.5 when driving and that's your charging system controlling when alternator charging

 

[luc]

Two questions about my 2015 Mustang Ecoboost premium:

what activity triggers the ‘check charging system’ alarm ?

does this car have a smart charging system? My voltage meter seems to fluctuate between just over 12 V. And around 14 volts. Would have expected a constant 14 volts if alternator was working properly.

Symptom - ‘Check charging system has come on twice in last few weeks. Each time I put battery on charge as it was low. I the. Noticed the fluctuations in the digital voltmeter reading on dash whilst driving.

alternator changed in around 2017 by dealer under warranty. Battery last changed in January 2024 ( about 4th one I have had !!)

It’s totally normal for the volt gauge to fluctuate that way

the car has a smart charging system and sometimes stays in low 12 if battery doesn’t need a charge
Check the 3 wires connector at the alternator, especially the sensing wire, for a break/lack of continuity
Pretty common problem on those cars

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