Code B123, Courtesy Lights Switch Circuit (TORONADO): Notes

The panel lights switch uses the same physical control as the dimming pot. Inside the left switch assembly, the panel lamp switch contacts close when the dimming slider is moved to its extreme maximum position (on). The BCM supplies a voltage on circuit No. 685 to the switch. When the slider is moved to the extreme maximum position (on), the switch contacts close and the signal voltage is pulled low. This will turn on the courtesy lights.

Code B123 indicates that the BCM terminal "2A5" was pulled to ground but the dimmer switch position was less than a value for maximum panel light brightness. A grounded circuit No. 685 will not only set Code B123, but will also turn the courtesy lights on at all times and run the battery down.

1. BCM input value BI01 displays the voltage state of the circuit at the BCM. These conditions can be observed in BCM input display BI01 as readings of "HIGH " or "LOW" when the dimming slider is moved. "HIGH" indicates circuit is not grounded and lights should be off.
2. By removing the switch assembly, a shorted switch can be detected by observing B101.
3. By removing the BCM connector, the short to ground can be isolated as being the wire or the BCM.