B2120 Lumbar Up/Down Sensor Failed (with AL2)

Diagnostic Trouble Code Chart (Part 1 Of 2):

Diagnostic Trouble Code Chart (Part 2 Of 2):

Wiring Schematic:

CIRCUIT DESCRIPTION
The Memory Seat Module (MSM) receives inputs from the lumbar vertical position sensor during memory recall and memory set functions. The potentiometer in the position sensor varies in resistance as the motor moves the lumbar support up and down within the seat back. The MSM receives a variable voltage input depending on the resistance of the potentiometer. During memory set, the MSM records the voltage across the lumbar vertical potentiometer. During memory recall, the MSM moves the lumbar vertical motor until the voltage across the potentiometer matches the voltages stored in memory. The lumbar support is not moved during the easy exit function. During normal operation, the lumbar vertical position sensor is checked against out-of-range voltage limits.

CONDITIONS FOR SETTING THE DTC
^ The MSM will set the DTC B2120 any time it detects that the lumbar horizontal sensor input voltage is out of range (less than 0.25 volts or greater than 4.75 volts).
^ DTC B2120 will set only if DTC B1982 MSM or DTC B1983 MSM is not current.

ACTION TAKEN WHEN THE DTC SETS
When DTC B2120 is set as current, the MSM will disable the lumbar vertical motor during memory recall operation. The lumbar vertical motor will remain enabled for manual positioning.

CONDITIONS FOR CLEARING THE DTC
^ The MSM detects that the lumbar vertical position sensor input is within the valid voltage range.
^ 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 Power Seat Systems Diagnostic System Check before continuing with the diagnosis of this DTC.
2. Multiple position sensor DTCs set indicates a concern with the reference wiring or MSM. Only one position sensor DTC set indicates a concern with the position sensor and wiring.
21. Clear all DTCs after the repair procedure is complete.