GM Service Manual Online
For 1990-2009 cars only

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 B1395 02: Device Voltage Reference Output Circuit Short to Ground

DTC B1395 05: Device Voltage Reference Output Circuit Short to Battery or Open

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

--

Steering Column Telescope Motor Signal

B2860 06

B2860 06

B2860 01

--

Steering Column Tilt Motor Signal

B2880 06

B2880 06

B2880 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 memory seat module (MSM) supplies a 5-volt reference voltage to the driver seat, lumbar, and tilt/telescoping steering column position sensors. The MSM monitors this reference voltage to ensure the accuracy of the voltages being returned from the sensors. If the voltage exceeds the normal operating range, errors will occur in the memory recall operations of the seat and tilt/telescoping steering.

Conditions for Running the DTC

The MSM must be powered.

Conditions for Setting the DTC

B1395 02

The reference voltage drops below 4.8 volts for more than 300 mS.

B1395 05

The reference voltage exceeds 5.2 volts for more than 300 mS.

Action Taken When the DTC Sets

All memory recall functions will be disabled.

Conditions for Clearing the DTC

    • The current DTC will clear and set the code to history, 3 seconds after the reference voltage returns to the normal operating range 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.
    • A short to voltage on one of the position sensor signal circuits may set this DTC.
    • An internal short to ground in one of the position sensors may set this DTC.

Reference Information

Schematic Reference

    •  Driver Seat Schematics
    •  Tilt/Telescoping Steering Column Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Memory Seats 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 Testing

  1. Ignition OFF, disconnect the harness connector for all position sensors connected to the 5-volt reference circuit.
  2. Ignition ON, observe all scan tool sensor parameters for Seat 1 and Column Info. The readings should be 0.0 volts.
  3. If greater than the specified value, test the appropriate signal circuit listed below for a short to voltage. If the circuit tests normal, replace the MSM.
    • Seat horizontal position sensor terminal 3 X2
    • Seat front vertical position sensor terminal 1 X2
    • Seat rear vertical position sensor terminal 5 X2
    • Recline position sensor terminal 2
    • Lumbar horizontal position sensor terminal 2
    • Lumbar vertical position sensor terminal 2
  4. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit at any one of the position sensors and ground.
  5. 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.
  6. Connect each position sensor one at a time and verify that the DTC does not set as current.
  7. If the DTC sets as current, replace the appropriate position sensor.
  8. If all circuits test normal, replace the MSM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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