GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2009 🢒 Lucerne 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 DTC B1825, B1850, B1860, B2105, B2355, B2365, or B2375

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B1825 01: Seat Recline Position Sensor Circuit Short to Battery

DTC B1825 06: Seat Recline Position Sensor Circuit Short to Ground or Open

DTC B1825 5A: Seat Recline Position Sensor Circuit Plausibility Failure

DTC B1850 01: Left Front Seat Lumbar Horizontal Position Sensor Circuit Short to Battery

DTC B1850 06: Left Front Seat Lumbar Horizontal Position Sensor Circuit Short to Ground or Open

DTC B1850 5A: Left Front Seat Lumbar Horizontal Position Sensor Circuit Plausibility Failure

DTC B1860 01: Left Front Seat Lumbar Vertical Position Sensor Circuit Short to Battery

DTC B1860 06: Left Front Seat Lumbar Vertical Position Sensor Circuit Short to Ground or Open

DTC B1860 5A: Left Front Seat Lumbar Vertical Position Sensor Circuit Plausibility Failure

DTC B2355 01: Left Seat Front Vertical Position Sensor Circuit Short to Battery

DTC B2355 06: Left Seat Front Vertical Position Sensor Circuit Short to Ground or Open

DTC B2355 5A: Left Seat Front Vertical Position Sensor Circuit Plausibility Failure

DTC B2365 01: Left Seat Rear Vertical Position Sensor Circuit Short to Battery

DTC B2365 06: Left Seat Rear Vertical Position Sensor Circuit Short to Ground or Open

DTC B2365 5A: Left Seat Rear Vertical Position Sensor Circuit Plausibility Failure

DTC B2375 01: Left Seat Assembly Horizontal Position Sensor Circuit Short to Battery

DTC B2375 06: Left Seat Assembly Horizontal Position Sensor Circuit Short to Ground or Open

DTC B2375 5A: Left Seat Assembly Horizontal Position Sensor Circuit Plausibility Failure

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

5-Volt Reference

B1395 02, B1825 06, B1850 06, B1860 06, B2355 06, B2365 06, B2375 06, B2860 06, B2880 06

B1825 06, B1850 06, B1860 06, B2355 06, B2365 06, B2375 06, B2860 06, B2880 06

B1395 05, B1825 01, B1850 01, B1860 01, B2355 01, B2365 01, B2375 01, B2860 01, B2880 01

B1825 5A, B1850 5A, B1860 5A, B2355 5A, B2365 5A, B2375 5A, B2860 5A, B2880 5A

Front Vertical Position Sensor Signal

B2355 06

B2355 06

B2355 01

--

Horizontal Position Sensor Signal

B2375 06

B2375 06

B2375 01

--

Lumbar Vertical Position Sensor Signal

B1860 06

B1860 06

B1860 01

--

Lumbar Horizontal Position Sensor Signal

B1850 06

B1850 06

B1850 01

--

Rear Vertical Position Sensor Signal

B2365 06

B2365 06

B2365 01

--

Recline Position Sensor Signal

B1825 06

B1825 06

B1825 01

--

Memory Seat/Mirror Sensor Low Reference

--

B1825 01, B1850 01, B1860 01, B2355 01, B2365 01, B2375 01, B2860 01, B2880 01

--

B1825 5A, B1850 5A, B1860 5A, B2355 5A, B2365 5A, B2375 5A, B2860 5A, B2880 5A

Circuit/System Description

The position 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 a low reference from the memory seat module (MSM). The sensor sends a voltage signal that varies with the movement of the seat through the 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.

Conditions for Setting the DTC

B1825 01, B1850 01, B1860 01, B2355 01, B2365 01, B2375 01

If the MSM sees the analog input from this sensor is greater than 4.75 volts, the sensor will be considered out of range and the MSM will set this DTC.

B1825 06, B1850 06, B1860 06, B2355 06, B2365 06, B2375 06

If the MSM sees the analog input from this sensor is less than 0.22 volt , the sensor will be considered out of range and the MSM will set this DTC.

B1825 5A, B1850 5A, B1860 5A, B2355 5A, B2365 5A, B2375 5A

This DTC will set, if the MSM is controlling a motor in one direction and its position sensor is tracking the motor in the opposite direction. The sensor is either mounted or wired incorrectly, or the polarity of the motor control circuits are reversed.

Action Taken When the DTC Sets

The MSM disables the memory recall and easy exit/entry action commands of the motor monitored by the sensor. The motor will respond to manual positioning commands.

Conditions for Clearing the DTC
    • The current DTC will clear and set to history, when the MSM sees the analog input from the sensor as between 0.22 volt and 4.75 volts and the ignition is cycled OFF then back to ACC or RUN.
    • The history DTC will clear after 50 consecutive fault-free ignition cycles have occurred.

Diagnostic Aids
    • All position sensors use common ground and 5-volt reference circuits.
    • If the 5-volt reference circuit is shorted to voltage multiple position sensor codes will set.
    • If the 5-volt reference circuit is shorted to ground multiple position sensor codes will set.
    • If the sensor ground circuit is open multiple codes will set.
    • DTC failure type 5A will set if the sensor setting this DTC is either mounted or wired incorrectly, or the polarity of the motor control circuits are reversed.

Reference Information

Schematic Reference

Driver Seat Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

    •  Memory Seats Description and Operation
    •  Lumbar Support Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, observe the scan tool Memory Seat Module driver seat and lumbar position sensor parameters. The readings should be between 0.22 volt and 4.75 volts and change while adjusting seat and lumbar positions.

Circuit/System Testing

B1825 01 or B1825 06

  1. Ignition OFF, disconnect the X2 harness connector at the seat recline motor.
  2. Test for less than 2 ohms between the low reference circuit terminal 3 and ground.
    3. ⇒If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the MSM.
  3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 1 and ground.
    4. ⇒If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.
    ⇒ If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the MSM.
  4. Verify the scan tool Driver Seat Recline Sensor parameter is less than 1 volt.
    5. ⇒If greater than the specified range, test the signal circuit terminal 2 for a short to voltage. If the circuit tests normal, replace the MSM.
  5. Install a 3A fused jumper wire between the signal circuit terminal 2 and the 5-volt reference circuit terminal 1. Verify the scan tool Driver Seat Recline Sensor parameter is greater than 4.75 volts.
    6. ⇒If less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.
  6. If all circuits test normal, test or replace the seat recline position sensor.

B2355 01, B2355 06, B2365 01, B2365 06, B2375 01 or B2375 06

  1. Ignition OFF, disconnect the X2 harness connector at the seat adjuster motor assembly.
  2. Test for less than 2 ohms between the low reference circuit terminal 2 and ground.
    3. ⇒If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the MSM.
  3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 6 and ground.
    4. ⇒If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.
    ⇒ If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the MSM.
  4. Verify the appropriate scan tool driver seat sensor parameter is less than 1 volt.
    5. ⇒If greater than the specified range, test the appropriate signal circuit listed below for a short to voltage. If the circuit tests normal, replace the MSM.
    • Seat front vertical position sensor terminal 1
    • Seat rear vertical position sensor terminal 5
    • Seat horizontal position sensor terminal 3
  5. Install a 3A fused jumper wire between the appropriate signal circuit listed below and the 5-volt reference circuit terminal 6. Verify the appropriate scan tool driver seat position sensor parameter is greater than 4.75 volts.
    6. • Seat front vertical position sensor terminal 1
    • Seat rear vertical position sensor terminal 5
    • Seat horizontal position sensor terminal 3
    ⇒If less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.
  6. If all circuits test normal, test or replace the seat position sensor.

B1850 01, B1850 06, B1860 01 or B1860 06

  1. Ignition OFF, disconnect the harness connector at the appropriate lumbar sensor.
  2. Test for less than 2 ohms between the appropriate low reference circuit listed below and ground.
    3. • Lumbar horizontal position sensor terminal 3
    • Lumbar vertical position sensor terminal 1
    ⇒If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the MSM.
  3. Ignition ON, test for 4.8-5.2 volts between the appropriate 5-volt reference circuit listed below and ground.
    4. • Lumbar horizontal position sensor terminal 1
    • Lumbar vertical position sensor terminal 3
    ⇒If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.
    ⇒If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the MSM.
  4. Verify the appropriate scan tool lumbar sensor parameter is less than 1 volt.
    5. ⇒If greater than the specified range, test the signal circuit terminal 2 for a short to voltage. If the circuit tests normal, replace the MSM.
  5. Install a 3A fused jumper wire between the signal circuit terminal 2 and the appropriate 5-volt reference circuit listed below: Verify the appropriate scan tool lumbar sensor parameter is greater than 4.75 volts.
    6. • Lumbar horizontal position sensor terminal 1
    • Lumbar vertical position sensor terminal 3
    ⇒If less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.
  6. If all circuits test normal, test or replace the lumbar position sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Front Seat Adjuster Replacement
    •  Front Seat Recliner Position Sensor Replacement
    •  Front Seat Lumbar Support Replacement
    •  Control Module References for MSM replacement, setup, and programming