Alternator & Starter Q&A
Alternator Q&A
Alternators operate on a supply and demand situation and do not have a set amperage output at idle.
On a 12 volt system the high cutout voltage should be between 14.3 - 14.9 depending on the voltage regulator installed on your alternator. This voltage will slowly drop off until the battery is fully charged and the electrical load is low.
- Worn out brushes
- A failed voltage regulator.
- Check the wiring at the voltage regulator plug, refer to your service manual for plug connections and what they should be.
- Battery main feed line or alternator ignition charge fuse
- Diode failure in the rectifier.
- Defective voltage regulator.
- Charge lamp burnt out.
- Bad diode in the alternator.
- Bad diode trio in the alternator.
- No power to alternator ignition charge line.
- Bad battery.
- Electrical system drain.
- Slipping belt.
- Alternator state of charge too low to maintain battery.
- Bad diode in alternator rectifier.
Defective voltage regulator.
- Loose or corroded battery connections.
- Bad battery.
- Bad alternator.
- Engine Idle speed low.
- Alternator output too low and not meeting electrical demand.
- High output alternators must spin faster than a standard alternator to keep the field engaged.
- Changing the pulley to a smaller diameter will usually correct this.
The higher amperage produced by the alternator will not pose any problems to the vehicle’s electrical system, but too high in voltage can.
Due to the increase in amperage, upgrading the alternator’s battery feed cable and vehicles primary ground cables is recommended.
Starter Q&A
- Battery voltage too low.
- Bad ground and or positive battery connection.
- Solenoid internal contacts worn.
- Starter motor brushes worn and not making contact with armature.
- Armature brush contact surface extremely dirty "contaminated with dirt, grease or oil".
- Battery voltage too low.
- Bad ground or positive battery connection.
- Armature brush contact surface extremely dirty "contaminated with dirt, grease or oil".
- Starter drive worn out.
- Bent or broken starter shift lever.
- Teeth missing in flywheel.
- Open circuit in solenoid.
- Open circuit in starter motor armature or field coil windings.