Circuit Description
When the power seat lumbar switches are pressed they send a 12-volt signal through the lumbar switch signal circuit 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 - Device Power 1 Circuit 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 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The DTC automatically clears when the switch circuit setting the DTC is no longer active.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.
-
Checks the existing state of the driver's 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.
-
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.
-
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 |
Does the scan tool display Inactive? | Go to Step 3 | Go to Step 4 | |
3 |
Does the Seat Lumbar switch parameter change state? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 4 |
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 memory seat module (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 Lumbar Switch Replacement . Did you complete the replacement? | Go to Step 10 | -- |
Does the DTC reset? | Go to Step 2 | System OK | |
