GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 DeVille 🢒 Body 🢒 Seats 🢒 DTC B1830, B1835, B1840, or B1845

DTC B1830, B1835, B1840, or B1845 w/o Massaging Lumbar-AM3

Circuit Description

When the lumbar switches are pressed they send a 12 volt signal through the switch signal circuits to the memory seat module (MSM). The MSM commands the lumbar support to move in response to the switch inputs.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

    • DTC B1830 Seat Lumbar Forward Switch Circuit
    • DTC B1835 Seat Lumbar Rearward Switch Circuit
    • DTC B1840 Seat Lumbar Up Switch Circuit
    • DTC B1845 Seat Lumbar Down Switch Circuit

Conditions for Running the DTC

The MSM must be powered and can not have DTC B1327 Battery Positive Low as an active DTC for this DTC to set.

Conditions for Setting the DTC
    • If a seat switch circuit continues to be active for 30 seconds after a 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 a switch DTC.
    • A switch DTC will not set if DTC B1327 or B1328 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The DTC automatically clears when the switch circuit setting the DTC is no longer active.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 drivers seat lumbar switch by using the current state of the input parameter. If all of the lumbar switch parameters display active, possibly one of the lumbar switch signal circuits is shorted to voltage.

    2.

  2. When the lumbar switch is disconnected, this step determines if the switch contacts are stuck closed, or if one of the switch signal circuits is possibly shorted to voltage.

    3.

  3. This step verifies the repair.

Step

Action

Yes

No

Schematic Reference: Driver Seat Schematics

Connector End View Reference: Power Seat Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the appropriate Seat Lumbar switch parameter in the Memory Seat Module (MSM) data list.

Does the scan tool display Inactive?

Go to Step 3

Go to Step 4

3
  1. With a scan tool, observe the appropriate Seat Lumbar switch parameter.
  2. Activate the suspect lumbar switch.

Does the Seat Lumbar switch parameter change state?

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

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the lumbar switch connector.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe all of the lumbar switch parameters in the MSM data list.

Does the scan tool display Inactive for all of the parameters?

Go to Step 7

Go to Step 5

5

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

Did you find and correct the condition?

Go to Step 10

Go to Step 6

6

Inspect for poor connections at the harness connector of the MSM. 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 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 9

8

Replace the MSM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 10

--

9

Replace the lumbar switch. Refer to Front Seat Lumbar Control Switch 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

DTC B1830, B1835, B1840, or B1845 with Massaging Lumbar-AM3

Circuit Description

When the lumbar switches are pressed they send a 12 volt signal through the switch signal circuits to the memory seat module (MSM). The MSM commands the lumbar support to move in response to the switch inputs.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

    • DTC B1830 Seat Lumbar Forward Switch Circuit
    • DTC B1835 Seat Lumbar Rearward Switch Circuit
    • DTC B1840 Seat Lumbar Up Switch Circuit
    • DTC B1845 Seat Lumbar Down Switch Circuit

Conditions for Running the DTC
    • The MSM must be powered.
    • DTC B1327 -- Battery Voltage Low can not be current.

Conditions for Setting the DTC
    • If a seat switch circuit continues to be active for 30 seconds after a 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 a switch DTC.

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 driver's seat lumbar switch by using the current state of the input parameter. If all of the seat switch parameters display active, possibly one of the lumbar switch signal circuits is shorted to voltage.

    2.

  2. When the seat switch is disconnected, this step determines if the lumbar switch contacts are stuck closed or if one of the switch signal circuits is possibly shorted to voltage.

    3.

  3. Determines if there is a short to battery positive voltage in the lumbar down output circuit of the massage module.

    4.

  4. This step verifies the repair.

Step

Action

Yes

No

Schematic Reference: Driver Seat Schematics

Connector End View Reference: Power Seat Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the appropriate Seat Lumbar switches parameter in the Memory Seat Module (MSM) data list.

Does the scan tool display Inactive?

Go to Step 3

Go to Step 4

3
  1. With a scan tool, observe the appropriate Seat Lumbar switches parameter.
  2. Activate the suspect lumbar switch.

Does the Seat Lumbar switches parameter change state?

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

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the lumbar switch.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe all of the Seat Lumbar switch parameters in the MSM data list.

Does the scan tool display Inactive for all of the Seat Lumbar switch parameters?

Go to Step 8

Go to Step 5

5

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

Did you find and correct the condition?

Go to Step 15

Go to Step 6

6
  1. Disconnect the massage module harness connector.
  2. With a scan tool, observe all of the Seat Lumbar switch parameters in the MSM data list.

Does the scan tool display Inactive for all of the Seat Lumbar switch parameters?

Go to Step 9

Go to Step 7

7

Test the suspect lumbar signal circuit between the MSM and the massage module for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 10

8

Test the lumbar up/down switch signal circuits between the lumbar switch and the massage module for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 11

9

Inspect for poor connections at the harness connector of the massage 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 15

Go to Step 13

10

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 15

Go to Step 12

11

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 15

Go to Step 14

12

Replace the MSM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 15

--

13

Replace the massage module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 15

--

14

Replace the lumbar switch. Refer to Front Seat Lumbar Control Switch Replacement .

Did you complete the replacement?

Go to Step 15

--

15

  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