Generator Functional Check

The generator functional check is designed to check for generator undercharging or overcharging of the battery. The following refers to steps in flow chart:

1. At key on, engine off, the battery volts telltale should be on.
2. If the battery volts telltale is on with the engine running, perform telltale lamp diagnosis. See TELLTALE LAMP DIAGNOSIS  .
3. Always diagnose codes B410, B411 and B412 before performing generator functional check. The trouble code charts will check the BCMs ability to detect generator faults, and to control generator operation.
4. This step checks for the generator overcharging the battery. Generator overcharging the battery may be accompanied by code B412 (either current or history), and BATTERY VOLTS HIGH MESSAGE on the Climate Control Driver Information Center. Code B410 accompanied by SERVICE ELECTRICAL SYSTEM message may also set. Visual signs of battery overcharge may include electrolyte leakage from the battery vents, low electrolyte level indicated by a Yellow battery eye, or low electrolyte levels seen through the side of the battery case.
5. This step checks for proper generator current output. Generator output below 90 amps at 1500 RPM may result in undercharging of the battery. Generator undercharging of the battery may be accompanied by a current or history code B411, and accompanied by SERVICE ELECTRICAL SYSTEM message may also set.

For generator functional check, refer to illustration. See Fig 1 .