B123 - Panel Courtesy Lamps Switch Circuit

Code B123 - Panel Lamp Switch Circuit:

Wiring Diagram for Codes B119, B120, B121, B122 & B123:

CODE B123 - PANEL COURTESY LAMPS SWITCH CIRCUIT

Circuit Description:

The panel lamp 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 max. (on) position. The BCM supplies a voltage on CKT 685 to the switch. When the slider is moved to the extreme max. (on) position the switch contacts close and the signal voltage is pulled low through ground CKT 804.

Code B123 will set if the ignition is on, the dimming pot has not failed (Code B122) and the signal voltage is "LO" when the dimming slider is moved off of the max position (shorted CKT).



Test Description:

1. BCM input B101 displays the voltage state of the circuit at the BCM. These conditions can be observed in BCM input display B101 as readings of "HI" or "LO" when the dimming slider is moved.

2. Check to see if the LO reading is due to the circuit or switch assembly. If the display changes from "LO" to "HI" when the switch assembly is disconnected, the BCM and wiring are 0K.

3. By removing the BCM connector, the short to ground can be isolated as being the wire or BCM.



Note on Intermittents:

If an intermittent code B123 is being set, manipulate CKT 685. When BCM input B101 change of state indicator displays an "X" check the circuit for an intermittent ground.

Cycle panel dimming control from min. to max. if BD42 does not read 6 to 94% see code B122.