Question about Ford Focus
Did u check that voltage under load? Check your voltage with the heater fan on 4, lights all on low/high,
defrost, radio on, and see what's saying.
Check battery. If good, then check your alternator output. If good, wiggle the connectors and check for fluctuation. Your car can be run with just the battery, but the only problem is that once you've drained your battery.
It shouldn't drop all the way down to 12 while the engine is running. But you need to do a carbon pile load test and measure the AMPERAGE. Granted, voltage changes with amperage change, but the proper way to test this is to load the alternator down to 12 volts, with a carbon pile (the knob on a VAT machine), holding the RPM at about 2000 and measure the amperage it is putting out at that point. But the battery sitting at 12V with just accessories turned on in the car is not right; can find other details HERE.
Sounds like some type of loose connection such as a battery or alternator connection. Less likely, but also possible-check the serpentine belt for proper tension. Loose connections will cause that light to come on whenever the circuit is broken. If it's under warranty, go to the dealer. Otherwise, check battery posts for tightness and/or corrosion as well as the alternator main output connection. Caution- if you do end up checking the alternator output connection, disconnect the battery ground connection first.
Keep in touch.
Posted on May 29, 2010
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Posted on Jan 02, 2017
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