GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2002 🢒 Eldorado 🢒 DTC 🢒 DTC B2109-B2112

Circuit Description

When the power seat switches are pressed, the memory seat module (MSM) receives an input from the switch. The MSM commands the driver seat to move in response to the switch input.

Conditions for Setting the DTC
    • If a seat switch continues to be active for 30 seconds after the motor controlled by that switch reaches the end of its travel, the switch will be considered shorted and the MSM will set the DTC.
    • If a position sensor DTC is current and the associated switch is active for 30 continuous seconds, the switch will be considered shorted and the MSM will set the DTC.
    • A switch DTC will not set if DTC B1982 MSM or DTC B1983 is current.

Action Taken When the DTC Sets
    • A motor output driven in response to a switch considered failed, is deactivated for both directions.
    • All memory recall commands are ignored.
    • The MSM will respond to any other switch input that has not set a DTC.

Conditions for Clearing the DTC

The DTC automatically clears when the switch circuit setting the DTC is no longer active.

Test Description

The numbers below refer to the step numbers on the diagnostic table:

  1. Checks the existing state of the lumbar switch by using the current state of the current state of the diagnostic trouble code (DTC) list.

    2.

  2. When the lumbar switch is disconnected, this step determines if the lumbar switch contacts are stuck closed, or if the related switch signal circuit is possibly shorted to ground.

    3.

  3. This step verifies the repair.

Step

Action

Yes

No

Schematic Reference: Lumbar Support Schematics

1

Did you perform the Diagnostic System Check-Power Seat System?

Go to Step 2

Go to Diagnostic System Check - Power Seat Systems

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the DTCs in the Memory Seat Module Current Diagnostic Trouble Code list.

Does the scan tool display a current lumbar switch DTC?

Go to Step 4

Go to Step 3

3
  1. With a scan tool, observe the Current Diagnostic Trouble Code list.
  2. Operate the appropriate lumbar switch.
  3. Wait for 30 seconds for the DTC to set.

Does the scan tool display a current lumbar switch DTC?

Go to Step 4

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

4

  1. Disconnect the lumbar switch harness connector.
  2. With a scan tool, observe the Current Diagnostic Trouble Code list.

Does the scan tool display the lumbar switch DTC?

Go to Step 5

Go to Step 6

5

Test the lumbar switch signal circuit that displays the related DTC for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 7

6

Inspect for poor connections at the harness connector of the lumbar switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 8

7

Inspect for poor connections at the harness connector of the memory seat module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 9

8

Replace the lumbar switch. Refer to Lumbar Switch Replacement .

Did you complete the replacement?

Go to Step 10

--

9

Replace the memory seat module. Refer to Memory Seat Control Module Replacement .

Did you complete the replacement?

Go to Step 10

--

10

  1. Use a scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK