B122 - Twilight Delay & Panel Dimming

Code B120 & B122:

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

Circuit Description:

Since both potentiometers use the same power and ground, chances are that the problem is in the power or ground circuits when both codes are stored.


Test Description:

1. BCM data value BD43 displays a twilight delay value. The normal range is between 6 and 94%.

2. Checks to see if the open or grounded circuit reading is due to the circuits or switch assembly. If voltage can be read across CKTS. 705 & 736 after disconnecting the switch assembly, the BCM and wiring are OK.

3. Check for 5 volt reference at the switch. If 5 volts is present, CKT 736 is open. If CKT 736 is open, the open will be between term. BC10 on left switch assembly and cavity B5 on the IP side of the Dash-IP transition connector.

4. If CKT 705 is suspected of being grounded, remove the HVAC programmer and BCM connectors prior to making a ground check.

4A. If there is no ground in CKT 705 replace HVAC programmer or BCM.


Note on Intermittents:

If intermittent codes B120 & B122 are being set, manipulate the related wiring while observing either BCM data value BD42 and/or BD43. If the failure is induced, the reading will jump from its normal value to a reading outside of its range, (see specific charts for range).