3116 and 3126 Truck Engines Problem Alternator Charge Too High

Probable Cause(s):

* Alternator Or Alternator Regulator Has Loose Connections
* Alternator Regulator Has A Defect
* Alternator Field Lead Shorted To Battery Voltage

1. Alternator or alternator regulator has loose connections:

Tighten all connections to alternator or alternator regulator.
2. Alternator regulator has a defect:

Replace the alternator regulator.
3. Alternator Field Lead Shorted To Battery Voltage

If the alternator field lead becomes shorted to battery voltage, the alternator will charge at maximum rate. When the battery becomes overcharged, voltage and current may rise to levels that result in damage to the battery, alternator and voltage regulator, and also any electrical equipment that is turned on. The ECM is protected up to 32 volts DC; voltages above that may damage the ECM.

Find and correct the short between alternator field circuit and battery voltage. Repair or replace any electrical equipment suffering subsequent damage.

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