GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2007 🢒 XLR 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 DTC B1735, B1740, B1745, B1750, B1755, B1760, B1815, or B1820

Circuit Description

When the power seat switches are pressed they send a 12-volt signal through the switch signal circuit to the memory seat module (MSM)/driver position module (DPM). The MSM/DPM then commands the driver seat to move in response to the switch inputs.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

    • DTC B1735 Seat Front Up Switch Circuit
    • DTC B1740 Seat Front Down Switch Circuit
    • DTC B1745 Seat Rear Up Switch Circuit
    • DTC B1750 Seat Rear Down Switch Circuit
    • DTC B1755 Seat Assembly Horizontal Forward Switch Circuit
    • DTC B1760 Seat Assembly Horizontal Rearward Switch Circuit
    • DTC B1815 Seat Recline Forward Switch Circuit
    • DTC B1820 Seat Recline Rearward Switch Circuit

Conditions for Running the DTC

The MSM/DPM must be powered and cannot have B1327 Battery Voltage Low as an active DTC for this DTC to set.

Conditions for Setting the DTC
    • If a seat switch 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/DPM will set a switch 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/DPM will set a switch DTC.

Action Taken When the DTC Sets
    • Current and history codes are set.
    • A motor output driven in response to a switch considered failed, is deactivated for both directions.
    • All memory recall commands and class 2 driver identifier are ignored.
    • The MSM/DPM will respond to any other switch signal 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    • The DTC automatically clears when the switch circuit setting the DTC is no longer active.
    • The MSM/DPM will clear the history DTC after 50 fault-free ignition cycles.

Diagnostic Aids

The MSM is also known as the DPM for this vehicle.

Test Description

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

  1. This step checks the existing state of the driver seat switch by using the current state of the seat switch parameter. If all of the seat switch parameters display active, possibly one of the seat switch signal circuits is shorted to voltage.

    2.

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

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

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the appropriate seat switch parameter in the Driver Position Module 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 switch parameter.
  2. Activate the appropriate seat switch.

Does the switch parameter change state?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the seat adjuster switch harness connector.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe all of the switch parameters in the Driver Position Module data list.

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

Go to Step 7

Go to Step 5

5

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

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)/driver position module (DPM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

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 seat adjuster switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 10

Go to Step 9

8

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

Did you complete the replacement?

Go to Step 10

--

9

Replace the seat adjuster switch. Refer to Driver Seat Adjuster and Recliner Switch Replacement .

Did you complete the replacement?

Go to Step 10

--

10
  1. Use the 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