GM Service Manual Online
For 1990-2009 cars only

DTC B1395 Rear Seat Module

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 Descriptor

DTC B1395 03: Device Voltage Reference Output Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Back Panel Position Switch Supply Voltage

B1395 03

1

--

--

Load Floor Position Switch Supply Voltage

B1395 03

1

--

--

Back Panel Position Switch Signal

B1395 03

1

1

--

Load Floor Position Switch Signal

B1395 03

1

--

--

1. Power third row seat inoperative

Circuit/System Description

Battery positive voltage is supplied at all times to the seat load floor position switch and the back panel position switch by the rear seat module (RSM). The RSM monitors these battery positive voltage supply circuits for the protection of internal circuitry of the module.

Conditions for Running the DTC

The ignition must be in the ACCESSORY, RUN or CRANK power mode.

Conditions for Setting the DTC

This DTC will set only when the RSM detects that the device switch voltage reference is less than 3 volts.

Action Taken When the DTC Sets

    • The RSM will not allow seat operation.
    • If this condition occurs during seat operation, the operation will be cancelled.

Conditions for Clearing the DTC

The DTC will clear when the RSM detects that the device switch voltage is greater than 3 volts.

Diagnostic Aids

    • When the rear folding seat back panel is in the folded position, the load flood position switch is closed to voltage.
    • When the rear folding seat is in either the seated or stowed positions, the back panel position switch is closed to voltage.

Reference Information

Schematic Reference

Rear Seat Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Power Seats System 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

Circuit/System Verification

  1. Ignition ON, observe the scan tool load floor switch parameter with the seat back panel in the folded position. The reading should be Inactive.
  2. Observe the scan tool back panel position switch parameter with the seat in either the seated or stowed positions. The reading should be Active.

Circuit/System Testing

  1. Ignition OFF, disconnect the X2 harness connector at the RSM.
  2. Test for infinite resistance between the voltage reference circuit terminal D1 and ground.
  3. If not the specified value, test the voltage reference circuit for a short to ground.
  4. Test for infinite resistance between the signal circuit terminal C10 and ground.
  5. If not the specified value, test the signal circuit for a short to ground.
  6. Test for infinite resistance between the voltage reference circuit terminal D2 and ground.
  7. If not the specified value, test the voltage reference circuit for a short to ground.
  8. Test for infinite resistance between the signal circuit terminal C11 and ground.
  9. If not the specified value, test the signal circuit for a short to ground.
  10. If all circuits test normal, replace the RSM.

Repair Instructions

Important: After performing this diagnostic test and the electrical or component repairs have been completed, the folding seat may be in an unknown state and out of calibration with the RSM. The RSM must be calibrated before the folding seat system will operate. Refer to Power Folding Seat Calibration .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for RSM replacement, setup, and programming

DTC B1395 Memory Seat Module

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, B2355 06, B2365 06, B2375 06, B3606 06, B3633 06

B1825 06, B1850 06, B2355 06, B2365 06, B2375 06, B3606 06, B3633 06

B1395 05, B1825 01, B1850 01, B2355 01, B2365 01, B2375 01, B3606 01, B3633 01

B1825 5A, B1850 5A, B2355 5A, B2365 5A, B2375 5A, B3606 5A

Adjustable Accelerator Pedal Position Sensor Signal

B3633 06

B3633 06

B3633 01

--

Adjustable Brake Pedal Position Sensor Signal

B3606 06

B3606 06

B3606 01

--

Front Vertical Position Sensor Signal

B2355 06

B2355 06

B2355 01

--

Horizontal Position Sensor Signal

B2375 06

B2375 06

B2375 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, B2355 01, B2365 01, B2375 01, B3606 01, B3606 61, B3633 01

--

B1825 5A, B1850 5A, B2355 5A, B2365 5A, B2375 5A, B3606 5A

Circuit/System Description

The memory seat module (MSM) supplies a 5-volt reference voltage to the driver seat position sensors and both adjustable pedals 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 adjustable pedals.

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.
    • A history DTC will clear after 50 consecutive fault-free ignition cycles have occurred.

Diagnostic Aids

    • The Memory Seat Module (MSM) may be referenced as the Driver Position Module.
    • 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
    •  Adjustable Pedal 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 connectors for all position sensors connected to the 5-volt reference circuit.
  2. Ignition ON, observe all scan tool sensor parameters for Seat 1 Info and Adj. Pedals 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.
    • Horizontal position sensor terminal B X2
    • Front vertical position sensor terminal C X2
    • Rear vertical position sensor terminal B X2
    • Recline position sensor terminal 3 X2
    • Lumbar position sensor terminal E
  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 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.

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