GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2003 🢒 LeSabre 🢒 Body and Accessories 🢒 Seats 🢒 DTC B1826, B1851, B1861, B2356, B2366, or B2376

Circuit Description

The sensor that set this diagnostic trouble code (DTC), is either attached to the seat directional motor drive cable or directly to the motor it monitors. It receives a 5 volt reference and low reference from the memory seat module. The sensor sends a voltage signal that varies with the movement of the seat through the sensor signal circuit to the MSM. Then based on this voltage signal, the MSM determines the position of the seat.

Conditions for Running the DTC
    • The MSM must be powered and cannot have B1327- Battery Voltage Low set as a current DTC for this DTC to set.
    • This test will run only when the motors are active.

Conditions for Setting the DTC

If the signal received by the MSM from a motor being driven in a commanded direction changes by more than 10 counts or 0.2 volts in the wrong direction, the MSM will set this DTC.

Action Taken When the DTC Sets
    • Current and history codes are set.
    • The MSM disables the affected motor during memory recall operations.
    • The affected motor will respond to manual positioning commands.

Conditions for Clearing the DTC

The MSM will clear the DTC as an active DTC whenever a manual switch is activated and the MSM senses that the sensor signal changes by more than 2 counts or 0.04 volts in the correct direction.

Diagnostic Aids

All position sensors use common 5 volt reference and low reference circuits.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. This step checks the direction in which the volts change as the switch is activated. The voltage should increase for the forward or up position and decrease for the rearward or down position.

    2.

  2. This step checks the polarity of the seat position sensor wiring.

    3.

  3. This step checks the polarity of the seat motor wiring.

    4.

  4. This step checks the polarity of the seat switch wiring.

Step

Action

Yes

No

Schematic Reference: Memory Seats Schematics or Lumbar Support Schematics

Connector End View Reference: Power Seat Connector End Views

1

Did you perform the Diagnostic System Check - Power Seat Systems?

Go to Step  2

Go to Diagnostic System Check - Power Seat Systems

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the appropriate Sensor parameter in the Memory Seat Module data list.
  4. Activate the appropriate seat switch in the FORWARD or UP direction.

Does the voltage increase?

Go to Step 9

Go to Step 3

3

Does the seat move in the commanded direction?

Go to Step 4

Go to Step 5

4

Verify that the seat position sensor wiring circuits are in the correct harness connector cavities.

Did you find and correct the condition?

Go to Step 9

Go to Step 7

5

Verify that the seat motor wiring circuits are in the correct harness connector cavities.

Did you find and correct the condition?

Go to Step 9

Go to Step 6

6

Verify that the seat switch wiring circuits are in the correct harness connector cavities.

Did you find and correct the condition?

Go to Step 9

Go to Step 7

7

Inspect for poor connection 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 9

Go to Step 8

8

Replace the memory seat module. Refer to Memory Seat Control Module Replacement .

Did you complete the replacement?

Go to Step 9

--

9
  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