Note On Intermittents

If circuit No. 685 were intermittently grounded, Code B123 could be stored. Manipulate circuit No. 685 while observing BCM input display BI01 with dimmer at a low setting. If short occurs, value will switch from HI to LO.

Also check BD42 display. Cycle panel dimming control from minimum to maximum. If BD42 display does not range between 2 and 98 percent, or never reads more than 75 percent, replace left switch assembly.

Fig 1: Code B123, Schematic, Courtesy Lamp Switch Circuit

Courtesy of GENERAL MOTORS CORP.

Fig 2: Code B123, Flow Chart, Courtesy Lamp Switch Circuit

Courtesy of GENERAL MOTORS CORP.