GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2007 🢒 Sierra Classic - 4WD 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC B1850, B1860, B1960, B2355, B2365, or B2375

Circuit Description

The driver seat module (DSM) monitors the positions of most of the seat adjuster motors using hall effect type position sensors. The hall effect position sensors are supplied with battery positive reference and ground circuits from the DSM. The position sensor signal circuits are supplied battery positive voltage through a resistor then monitored within the DSM. During adjuster motor operation the hall effect position sensor provides a single pulse for every adjuster motor shaft rotation. The DSM counts the pulses from the position sensor signal circuits to determine the adjuster motor positions when storing or recalling memory seat position settings.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

    • DTC B1850 Driver Seat Lumbar Position Sensor Circuit
    • DTC B1960 Driver Seat Side Bolster Position Sensor Circuit
    • DTC B2355 Driver Seat Front Vertical Position Sensor Circuit
    • DTC B2365 Driver Seat Rear Vertical Position Sensor Circuit
    • DTC B2375 Driver Seat Horizontal Position Sensor Circuit

Conditions for Running the DTC

The system voltage must be between 9-16 volts.

Conditions for Setting the DTC

The DSM does not detect position sensor movement during adjuster motor operation.

Action Taken When the DTC Sets
    • The affected seat adjuster motor will operate approximately 1 revolution and stop each time the adjuster switch is activated.
    • The memory recall functions for the seat motor with a current status DTC will be disabled.
    • When the fault is no longer present a history status DTC will be stored, and memory operation will be restored.

Conditions for Clearing the DTC
    • The DTC will be current for as long as the fault is present.
    • When the fault is no longer present the DTC will be a history status code.
    • The history DTC will be cleared after 100 error free ignition cycles, or by using the scan tool clearing DTCs feature.

Test Description

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

  1. During this test the DSM must see an active switch input before power will be supplied the position sensor.

    2.

  2. During this test the DSM must see an active switch input before power will be supplied the position sensor.

    3.

  3. During this test the DSM must see an active switch input before power will be supplied the position sensor.

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

Verify the condition is present.

Does the system operate normally?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

  1. Disconnect the position sensor connector to the motor for which the DTC has set.
  2. Connect a DMM from the positive voltage reference circuit terminal in the position sensor harness connector to a good ground.
  3. Press the adjuster switch in either direction.

Does the DMM display battery voltage when the adjuster switch is pressed?

Go to Step 4

Go to Step 6

4

  1. Connect a DMM from the positive voltage reference circuit terminal to the low reference circuit terminal in the position sensor harness connector.
  2. Press the adjuster switch in either direction.

Does the DMM display battery voltage when the adjuster switch is pressed?

Go to Step 5

Go to Step 7

5

  1. Connect a DMM from the signal circuit terminal to the low reference circuit terminal in the position sensor harness connector.
  2. Press the adjuster switch in either direction.

Does the DMM display battery voltage when the adjuster switch is pressed?

Go to Step 9

Go to Step 8

6

Test the position sensor positive voltage reference circuit for the following conditions:

    •  An open
    • A short to ground
    • A short to voltage

Refer to Circuit Testing and to Wiring Repairs.

Did you find and correct the condition?

Go to Step 13

Go to Step 10

7

Test the position sensor low reference circuit for an open or short to voltage. Refer to Circuit Testing and to Wiring Repairs.

Did you find and correct the condition?

Go to Step 13

Go to Step 10

8

Test the position sensor signal circuit for the following conditions:

    • An open
    • A short to ground
    • A short to voltage

Refer to Circuit Testing and to Wiring Repairs.

Did you find and correct the condition?

Go to Step 13

Go to Step 10

9

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

Did you find and correct the condition?

Go to Step 13

Go to Step 11

10

Inspect for poor connections at the harness connector of the driver seat module (DSM). Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs.

Did you find and correct the condition?

Go to Step 13

Go to Step 12

11

Replace the appropriate adjuster motor assembly. Refer to Front Seat Adjuster Motor Replacement or Front Seat Lumbar Support Replacement .

Did you complete the replacement?

Go to Step 13

--

12

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

Did you complete the replacement?

Go to Step 13

--

13
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC.

Does the DTC reset?

Go to Step 3

System OK