Circuit Description
The memory seat module (MSM) receives inputs from the lumbar vertical position sensor during the following functions:
| • | Memory recall |
| • | Memory set |
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 sets the DTC B2120 any time the MSM 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 sets 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 Memory Seat Module (MSM) disables the lumbar vertical motor during memory recall operation. The lumbar vertical motor remains 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:
-
Perform the Power Seat Systems Diagnostic System Check before continuing with the diagnosis of this DTC.
-
Multiple position sensor DTCs set indicates a concern with the reference wiring or memory seat module (MSM). Only one position sensor DTC set indicates a concern with the position sensor and wiring.
-
Clear all DTCs after the repair procedure is complete.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Was the entire Power Seat Systems Diagnostic System Check performed? | -- | Go to Step 2 | ||
Are any other position sensor DTCs set? | -- | Go to Step 3 | Go to Step 9 | |
3 |
Important: When reconnecting the position sensor connector, ensure that the connector is connected in the proper direction. If the connector is reversed, improper memory operation will result. Is the resistance within the specified range? | 9000-11000 ohms | Go to Step 4 | Go to Step 12 |
4 | Connect a DMM from the lumbar vertical position sensor cavity C (BLK) to cavity B (BRN). Is the resistance within the specified range? | 500-9500 ohms | Go to Step 5 | Go to Step 12 |
5 |
Is the resistance less than the specified value? | 5 ohms | Go to Step 6 | Go to Step 13 |
6 | Connect a DMM from the lumbar vertical position sensor connector cavity B (BRN) to the MSM connector C1 cavity 12 (BLK). Is the resistance less than the specified value? | 5 ohms | Go to Step 7 | Go to Step 14 |
7 | Connect a DMM from the lumbar vertical position sensor connector cavity C (BLK) to ground. Is the resistance less than the specified value? | 5 ohms | Go to Step 15 | Go to Step 8 |
8 | Connect a DMM from the lumbar vertical position sensor connector cavity C (BLK) to the MSM connector C1 cavity 3 (LT BLU). Is the resistance less than the specified value? | 5 ohms | Go to Step 20 | Go to Step 16 |
9 |
Is the resistance less than the specified value? | 5 ohms | Go to Step 17 | Go to Step 10 |
10 | Connect a DMM from the lumbar vertical position sensor connector cavity D (LT BLU) to the MSM connector C1 cavity 13 (GRY). Is the resistance less than the specified value? | 5 ohms | Go to Step 11 | Go to Step 18 |
11 | Connect a DMM from the lumbar vertical position sensor connector cavity C (BLK) to the MSM connector C1 cavity 12 (BLK). Is the resistance less than the specified value? | 5 ohms | Go to Step 20 | Go to Step 19 |
12 | Replace the lumbar vertical position sensor. Is the lumbar vertical position sensor replacement complete? | -- | Go to Step 21 | -- |
13 | Repair the open in CKT 788 (LT BLU) between S331 and the lumbar vertical position sensor. Refer to Wiring Repairs in Wiring Systems. Is the circuit repair complete? | -- | Go to Step 21 | -- |
14 | Repair the open in CKT 782 (BRN) between S321 and the lumbar vertical position sensor. Refer to Wiring Repairs in Wiring Systems. Is the circuit repair complete? | -- | Go to Step 21 | -- |
15 | Repair the short in CKT 1062 (BLK or LT BLU). Refer to Wiring Repairs in Wiring Systems. Is the circuit repair complete? | -- | Go to Step 21 | -- |
16 | Repair the open in CKT 1062 (BLK or LT BLU) between the MSM and the lumbar vertical position sensor. Refer to Wiring Repairs in Wiring Systems. Is the circuit repair complete? | -- | Go to Step 21 | -- |
17 | Repair the short in CKT 788 (LT BLU or BRN). Refer to Wiring Repairs in Wiring Systems. Is the circuit repair complete? | -- | Go to Step 21 | -- |
18 | Repair the open in CKT 788 (GRY) between the MSM and S348. Refer to Wiring Repairs in Wiring Systems. Is the circuit repair complete? | -- | Go to Step 21 | -- |
19 | Repair the open in CKT 782 (BLK) between the MSM and the S349. Refer to Wiring Repairs in Wiring Systems. Is the circuit repair complete? | -- | Go to Step 21 | -- |
20 | Replace the memory seat module (MSM). Refer to Memory Seat Control Module Replacement . Is the MSM replacement complete? | -- | Go to Step 21 | -- |
Is the action complete? | -- | -- |
