Noise from a generator may be caused by a loose drive pulley,
loose mounting bolts, worn or dirty bearings, defective diode, or a defective
stator. A high frequency whine or magnetic noise may be heard at full
output. This is a normal condition.
Perform an output test in order to help distinguish bearing noise from
the magnetic noise, also called a whine. Refer to
Generator Not Operating Properly
. A shorted bridge diode will reduce
output to 1/3 of the rating and have a growling noise when at high load.
It is also helpful to listen to the generator with a moderate load (engine
cooling fans or headlights on) in order to determine if there is a bearing
or magnetic noise.
In order to avoid damage to the electrical equipment, observe the following
precautions:
| • | Do not reverse the connections to the generator. |
| • | Do not short across or ground any of the terminals in the charging
circuit except as directed by the service manual. |
| • | Do not apply the battery voltage directly to the generator L terminal
for testing. A 400 - 500 ohm resistor must be used. |
| • | Never disconnect the battery cables from the output terminal or
the battery while the generator is operating. |
| • | When connecting a charger or booster battery to the car battery,
refer to
Battery Charging
. |
Trouble in the charging system can be detected by the following conditions:
| • | The charge indicator does not light during bulb test, does not
go out after the engine start, or turns back on while the engine is running. |
| • | Service Engine Soon light turns on. |
| • | An overcharged batter as evidenced by spewing of electrolyte from
the vents. |
If an undercharged or overcharged battery condition occurs, the following
procedure may be used to diagnose the charging system:
- Visually inspect the accessory drive belt for damage or looseness.
- Inspect the charging circuit electrical connections for damage
or looseness. Refer to
Battery Is Undercharged or Overcharged
.
