B1845 Driver Lumbar Down Switch CKT Malf (A45 With AM3)

DTC B1845 Driver Lumbar Down Switch CKT Malf (A45 With AM3):

CIRCUIT DESCRIPTION
The Memory Seat Module (MSM) receives an input from the lumbar switch through the lumbar massage module when the down switch is actuated. When the lumbar switch is operated in the down direction, battery positive voltage (B+) is supplied to the MSM lumbar down input via CKT 1067 (YEL/BLK). The MSM recognizes the input and moves the lumbar support in the down direction.

CONDITIONS FOR SETTING DTC
^ When the lumbar down switch is active for 30 seconds after motion has ceased, the switch will be considered shorted and the DTC will set.
^ If the lumbar vertical position sensor DTC B1860 is current and the lumbar down switch is active for 30 seconds, the switch will be considered shorted and the DTC will set.
^ DTC B1845 will set only if DTC B1328 MSM or DTC B1327 MSM is not current.

ACTION TAKEN WHEN THE DTC SETS
^ The MSM will not move the lumbar support in the down direction.
^ The MSM will continue to respond to valid inputs from the other manual switches.
^ All memory recall function commands will be ignored for all directions.

CONDITIONS FOR CLEARING THE DTC
^ The MSM sees that the lumbar down switch is no longer active.
^ Use the On-Boards clearing DTCs feature.
^ Use a scan tool.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table:
1. Perform the entire Power Seat Systems Diagnostic System Check before continuing with the diagnosis of this DTC.
2. Determines whether there is a stuck switch in the lumbar switch. DTC B1845 will set again if there is a short in the wiring or if there is an internal lumbar massage module problem. DTC B1845 will not set again if there is a stuck switch because the switch has been disconnected from the lumbar massage module input.
3. Determines whether there is an internal problem with the lumbar massage module or if there is a short to ground in the input wiring to the lumbar massage module or to the MSM.
11. Clear all DTCs after the repair procedure is complete.