Charging Indicator Light
This dash light alerts driver to charging system malfunctions. The light is operating properly if it meets the following conditions:
| Ignition Switch | Indicator Light | Engine |
|---|---|---|
| Off | Off | Stopped |
| On | On | Stopped |
| On | Off | Running |
If the indicator light is working properly and the light comes on when the engine is running, a complete check of the charging system must be made to determine the defective component.
NOTE:
Delco-Remy charging systems in 1975 and later GM vehicles have a new feature to warn the driver of a charging system open circuit malfunction, such as an open field winding in the alternator or an open voltage regulator. If a problem of this kind occurs, the indicator lamp will light. This is accomplished by the addition of a 40 ohm resistor across the voltage regulator in the alternator. With this new system, the indicator lamp may glow when the engine is first starter and remains at a slow idle. This does not indicate a charging system problem. As the engine speed increases to 900 RPM or more, the lamp will go out and remain out, even when the engine returns to idle.
CAUTION:
Observe the following safety rules and procedures when any testing is to be done to the alternator or voltage regulator:
- Check condition and charge level of the battery. A minimum specific gravity of 1.220 is required for proper operation. If the specific gravity is low, charge the battery to at least the minimum level. A defective battery can put an excessive demand on the alternator. Battery voltage will be low and the alternator will operate at or near its maximum output. An alternator can be damaged if operated for sustained periods at its maximum output. Prolonged high charge rates can result in overheating of the stator windings and eventual failure.
- When connecting a charger or booster battery to the vehicle battery, place a shop towel over the battery openings. Connect the positive cable from the booster battery to the discharged battery first, then connect one end of the negative (ground) cable to the booster battery and the other end to a good ground connection away from the discharged battery. This procedure will prevent arcing at the battery which might result in an explosion or fire. It is also recommended that safety goggles be worn when performing this operation.
- Inspect battery cables. Replace all frayed or worn cables. Be sure cable is correct gauge and meets OEM specifications. Cable connections must be clean and tight.
- Always disconnect the battery ground cable from the battery negative post before making any test connections or removal of any components. This procedure will prevent arcing or accidental short circuits.
- Make sure the alternator and battery have the same ground polarity.NOTE: Some early model vehicles have a positive ground electrical system.
- Do not short out or ground any terminal of the alternator or regulator.
- Do not operate an alternator without the proper electrical load. Extremely high voltages which are both dangerous and damaging to the alternator will result if the alternator is operated on an open circuit.
- When adjusting belt tension be careful in applying pressure to the alternator as the aluminum housing can be easily cracked.
- Do not attempt to polarize an alternator. Polarizing an alternator is not necessary since it contains no permanent magnets.
- Be certain the alternator drive belt (s) has proper tension to assure correct alternator output and to avoid excessive drive belt and alternator bearing wear.NOTE: Before beginning testing of the charging system, inspect all wire connectors, battery terminals and ground connections for loose connections, corrosion, damage or broken wires. Clean, tighten or repair any poor connections and check charging system.