For 1990-2009 cars

## 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 Symptoms - Seats
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 light 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 light 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 light 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 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 11
9 | Repair the open in the battery positive voltage circuit of the lumbar switch. Refer to Wiring Repairs . Is the trouble corrected? | Go to Step 13 | --
10 | Repair the open in the ground circuit of the lumbar switch. Refer to Wiring Repairs . Is the trouble corrected? | Go to Step 13 | --
11 | Replace the lumbar switch. Refer to Front Seat Lumbar Support Replacement . Have you finished the replacement? | Go to Step 13 | --
12 | Replace the lumbar motor. Refer to Front Seat Lumbar Support Replacement . Have you finished the replacement? | Go to Step 13 | --
13 | Operate the system to verify the repair. Did you correct the condition? | System OK | Go to Step 2

## Lumbar Support Inoperative with A45

### Diagnostic Aids

The memory seat module (MSM) is also referenced as the driver position module (DPM) for this vehicle.

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 motors through the 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 | Is the seat lumbar system inoperative in all directions? | Go to Step 4 | Go to Step 7
4 |

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

Does the Lumbar Forward Switch parameter display Active?

Go to Step 14

Go to Step 5

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 light illuminate? | Go to Step 6 | Go to Step 15
6 |

1. Probe anyone of the lumbar switch signal circuits with a test that is connected to a good ground.
2. Operate the appropriate lumbar switch.

Does the test light illuminate?

Go to Step 14

Go to Step 13

7 |

1. Install a scan tool.
2. With a scan tool, observe the appropriate Lumbar Switch parameters in the Driver Position Module data list.
3. Operate the lumbar switch in both directions.

Did the Lumbar Switch parameters display Active for both directions?

Go to Step 9

Go to Step 8

8 |

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 suspect lumbar switch signal circuit of the harness connector.
3. With a scan tool, observe the appropriate lumbar switch parameter.

Does the lumbar switch parameter display Active?

Go to Step 13

Go to Step 10

9 |

1. Disconnect the inoperative 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 light illuminate in both directions?

Go to Step 12

Go to Step 11

10 | 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 19 | Go to Step 14
11 | 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 19 | Go to Step 14
12 | 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 19 | Go to Step 17
13 | 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 19 | Go to Step 16
14 | 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 19 | Go to Step 18
15 | Repair the 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 19 | --
16 | Replace the lumbar switch. Refer to Front Seat Lumbar Support Replacement . Have you finished the replacement? | Go to Step 19 | --
17 | Replace the inoperative lumbar motor. Refer to Front Seat Lumbar Support Replacement . Have you finished the replacement? | Go to Step 19 | --
18 | Replace the MSM. Refer to Control Module References for replacement, setup and programming. Have you finished the replacement? | Go to Step 19 | --
19 | Operate the system to verify the repair. Did you correct the condition? | System OK | Go to Step 2