Code B122, Panel Dimming Potentiometer Circuit: Notes

Panel dimmer is a potentiometer which indicates desired display intensity to BCM. BCM supplies voltage on circuit No. 705 and a ground on circuit No. 736 to potentiometer in left switch assembly. Wiper provides voltage signal to BCM on circuit No. 686, indicating position of slider. When slider is moved toward maximum (bright) position, its resistance decreases and signal voltage increases. When slider is moved toward minimum (dim) position, its resistance increases and signal voltage decreases.

Code B122 will set if signal voltage indicates less than 2 percent (open or grounded circuit) or greater than 98 percent (shorted to voltage). During time failure is present, a substitute delay time will be implemented to allow continued operation of interior lighting. Reading from potentiometer BD42 display will indicate actual reading.

1. Checks to see if open or grounded circuit reading is due to circuits or switch assembly. If open or grounded circuit reading changes to a short to voltage reading after jumpering switch assembly terminals, BCM and wiring are okay.
2. Measuring voltage between circuit No. 705 and ground will determine if circuit No. 686 is open or shorted to ground.
3. Checks to see if short to voltage circuit reading is due to circuit or switch assembly. If a short to voltage reading changes to an open circuit reading after disconnecting switch assembly, BCM and wiring are okay.