GM Service Manual Online
For 1990-2009 cars only

Lumbar Support Inoperative w/o A45

Step

Action

Yes

No

Schematic Reference: Driver Seat Schematics or Passenger Seat Schematics

Connector End View Reference: Power Seat Connector End Views

DEFINITION: One or more of the power lumbar functions are inoperative.

1

Did you review the Lumbar Support System Description and Operation and perform the necessary inspections?

Go to Step 2

Go to Lumbar Support Description and Operation

2

Verify that the Lumbar Support Inoperative complaint is present, by attempting to operate the lumbar support motor through it's full range of adjustment.

Does the lumbar support system operate as described in the system description and operation?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

  1. Disconnect the lumbar switch harness connector.
  2. Connect a test lamp from the battery positive voltage circuit of the switch connector to a good ground.

Does the test lamp illuminate?

Go to Step 4

Go to Step 9

4

Connect a test lamp between the battery positive voltage circuit of the switch connector and the ground circuit of the switch connector.

Does the test lamp illuminate?

Go to Step 5

Go to Step 10

5

  1. Disconnect the lumbar motor harness connector.
  2. Connect a test lamp between the motor control circuits of the harness connector.
  3. Operate the lumbar switch in both directions.

Does the test lamp illuminate in both directions?

Go to Step 7

Go to Step 6

6

Test the motor control circuits for a short to ground or an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 8

7

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

Did you find and correct the condition?

Go to Step 13

Go to Step 12

8

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

Did you find and correct the condition?

Go to Step 13

Go to Step 11

9

Repair the open in the battery positive voltage circuit of the lumbar switch. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 13

--

10

Repair the open in the ground circuit of the lumbar switch. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 13

--

11

Replace the lumbar switch. Refer to Lumbar Switch Replacement .

Did you complete the replacement?

Go to Step 13

--

12

Replace the lumbar motor Refer to Front Seat Lumbar Support Replacement .

Did you complete the replacement?

Go to Step 13

--

13

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2

Lumbar Support Inoperative w/A45

Test Description

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

  1. This step tests the integrity of the signal circuits of the seat lumbar switch. If the fuse in the jumper wire opens when you perform this test, a short to ground may have occurred.

Step

Action

Yes

No

Schematic Reference: Driver Seat Schematics

Connector End View Reference: Power Seat Connector End Views

DEFINITION: One or more of the lumbar support functions are inoperative.

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Verify that the lumbar support inoperative complaint is present.
  2. Attempt to operate the lumbar motor through it's full range of adjustment.

Does the lumbar system operate as described in the system description and operation?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the Seat Lumbar Forward parameter in the Memory Seat Module data list.
  4. Operate the lumbar switch in the FORWARD direction.

Does the Seat Lumbar Forward parameter change state?

Go to Step 4

Go to Step 5

4

  1. With a scan tool, observe the Seat Lumbar Rearward parameter in the Memory Seat Module data list.
  2. Operate the lumbar switch in the REARWARD direction.

Does the Seat Lumbar Rearward parameter change state?

Go to Step 8

Go to Step 7

5

Probe the battery positive voltage circuit of the lumbar switch with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 6

Go to Step 14

6

  1. Disconnect the lumbar switch harness connector.
  2. Connect a 3-amp fused jumper wire between the battery voltage circuit of the harness connector and the lumbar forward switch signal circuit of the harness connector.
  3. With a scan tool, observe the Seat Lumbar Forward parameter.

Does the Seat Lumbar Forward parameter change state?

Go to Step 12

Go to Step 9

7

  1. Disconnect the lumbar switch harness connector.
  2. Connect a 3-amp fused jumper wire between the battery voltage circuit of the harness connector and the lumbar rearward switch signal circuit of the harness connector.
  3. With a scan tool, observe the Seat Lumbar Rearward parameter.

Does the Seat Lumbar Rearward parameter change state?

Go to Step 12

Go to Step 9

8

  1. Disconnect the lumbar motor harness connector.
  2. Connect a test lamp between the motor control circuits of the harness connector.
  3. Operate the lumbar switch in both directions.

Does the test lamp illuminate in both directions?

Go to Step 11

Go to Step 10

9

Test the suspect switch signal circuit between the lumbar switch and the memory seat module (MSM) for an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 18

Go to Step 13

10

Test the motor control circuits between the MSM and the inoperative lumbar motor for a short to ground or an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 18

Go to Step 13

11

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

Did you find and correct the condition?

Go to Step 18

Go to Step 16

12

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

Did you find and correct the condition?

Go to Step 18

Go to Step 15

13

Inspect for poor connections at the harness connector of the MSM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 18

Go to Step 17

14

Repair the short to ground or open in the battery positive circuit of the lumbar switch. Refer to Wiring Repairs or Connector Repairs .

Did you find and correct the condition?

Go to Step 18

--

15

Replace the lumbar switch. Refer to Lumbar Switch Replacement .

Did you complete the replacement?

Go to Step 18

--

16

Replace the lumbar motor. Refer to Front Seat Lumbar Support Replacement .

Did you complete the replacement?

Go to Step 18

--

17

Replace the MSM. Refer to Control Module References for replacement, setup and programming.

Did you complete the replacement?

Go to Step 18

--

18

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2