Generator Load Input High (Ford)
What does P1246 mean?
The P1246 code means the vehicle's onboard diagnostic system has detected: Generator Load Input High (Ford). This is a moderate severity code.
Common Symptoms
- Check Engine Light on
- Battery overcharging symptoms
- Bulging battery case
- Burning smell from electrical components
- Headlights excessively bright
Probable Causes (Ranked by Likelihood)
- Alternator voltage regulator stuck in high output Very High
- Shorted alternator field control wire High
- Faulty PCM alternator load monitoring circuit Moderate
- Aftermarket alternator with incorrect output specs Moderate
- Corroded wiring causing false high signal Low
Step-by-Step Diagnostic Procedure
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Measure charging voltage at battery at various RPMs
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Check if voltage exceeds 15.5 volts indicating overcharging
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Inspect alternator field control wire for shorts to power
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Verify correct alternator part number for the application
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Monitor generator load PID on scan tool during operation
Frequently Asked Questions
Is overcharging dangerous?
Yes. Overcharging can cause the battery to overheat, swell, and in extreme cases rupture. It can also damage sensitive electronic modules.
What voltage is too high for a car battery?
Normal charging voltage is 13.5-14.8 volts. Above 15.0 is concerning, and above 15.5 indicates a definite overcharge condition.
Can I disconnect the alternator as a temporary fix?
No. Without the alternator, the vehicle runs on battery alone and will die within 30-60 minutes. Replace the alternator or voltage regulator.