Code B409, Charging System Problem (Riviera): Notes

The 17SI generator has fault detection capability built into the regulator. The generator will pull circuit No. 225 low if the regulator detects any of the following problems: Open or shorted field circuit, drive belt break, overvoltage, and undervoltage conditions. Circuit No. 225 will normally have 12 volts out of the BCM to the generator in order to continuously signal the regulator. A short to ground on circuit No. 225 will cause the generator to not work, as the 12-volt signal from the BCM never reaches the generator, and a Code B409 will be set. An open in circuit No. 225 set Code B410 only (see Code B410 chart). Code B409 will set if the engine speed is greater than 600 RPM (Code B334 must not be set, otherwise the ECM cannot communicate engine speed to the BCM) and the BCM sees a low.

1. BCM input BI51 displays generator signal voltage as "HIGH" or "LOW", depending on the voltage state at the BCM. Normally with ignition on, engine off, circuit No. 225 will be pulled "LOW" by the generator and BI51 will read "LOW".
2. Checks to see if the "LOW" reading is due to the circuit or the generator. If display reading changes from "LOW" to "HIGH" when the generator is disconnected, with engine running, the BCM and wiring are okay.
3. Checks to see if the "LOW" reading is due to the BCM or the circuit. If display reading changes from "LOW" to "HIGH" when BCM connector 3 is removed, the BCM is okay.