GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2008 🢒 STS 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 DTC B1735, B1740, B1745, B1750, B1755, B1760, B1815, B1820, B1830, B1835, B1840, B1845, B1940, or B1945

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 B1735 01: Seat Front Up Switch Circuit Short to Battery

DTC B1740 01: Seat Front Down Switch Circuit Short to Battery

DTC B1745 01: Seat Rear Up Switch Circuit Short to Battery

DTC B1750 01: Seat Rear Down Switch Circuit Short to Battery

DTC B1755 01: Seat Assembly Forward Switch Circuit Short to Battery

DTC B1760 01: Seat Assembly Rearward Switch Circuit Short to Battery

DTC B1815 01: Seat Recline Forward Switch Circuit Short to Battery

DTC B1820 01: Seat Recline Rearward Switch Circuit Short to Battery

DTC B1830 01: Seat Lumbar Forward Switch Circuit Short to Battery

DTC B1835 01: Seat Lumbar Rearward Switch Circuit Short to Battery

DTC B1840 01: Lumbar Up Switch Circuit Malfunction

DTC B1845 01: Seat Lumbar Down Switch Circuit Short to Battery

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Front Vertical Up Switch Signal

1

1

B1735 01, B1740 01, B1745 01, B1750 01, B1755 01, B1760 01, B1815 01, B1820 01, B1830 01, B1835 01, B1840 01, B1845 01

--

Front Vertical Down Switch Signal

1

1

B1735 01, B1740 01, B1745 01, B1750 01, B1755 01, B1760 01, B1815 01, B1820 01, B1830 01, B1835 01, B1840 01, B1845 01

--

Horizontal Forward Switch Signal

1

1

B1735 01, B1740 01, B1745 01, B1750 01, B1755 01, B1760 01, B1815 01, B1820 01, B1830 01, B1835 01, B1840 01, B1845 01

--

Horizontal Rearward Switch Signal

1

1

B1735 01, B1740 01, B1745 01, B1750 01, B1755 01, B1760 01, B1815 01, B1820 01, B1830 01, B1835 01, B1840 01, B1845 01

--

Driver Seat Lumbar Down Switch Signal

2

2

B1735 01, B1740 01, B1745 01, B1750 01, B1755 01, B1760 01, B1815 01, B1820 01, B1830 01, B1835 01, B1840 01, B1845 01

--

Driver Seat Lumbar Forward Switch Signal

2

2

B1735 01, B1740 01, B1745 01, B1750 01, B1755 01, B1760 01, B1815 01, B1820 01, B1830 01, B1835 01, B1840 01, B1845 01

--

Driver Seat Lumbar Rearward Switch Signal

2

2

B1735 01, B1740 01, B1745 01, B1750 01, B1755 01, B1760 01, B1815 01, B1820 01, B1830 01, B1835 01, B1840 01, B1845 01

--

Driver Seat Lumbar Up Switch Signal

2

2

B1735 01, B1740 01, B1745 01, B1750 01, B1755 01, B1760 01, B1815 01, B1820 01, B1830 01, B1835 01, B1840 01, B1845 01

--

Recline Forward Switch Signal

1

1

B1735 01, B1740 01, B1745 01, B1750 01, B1755 01, B1760 01, B1815 01, B1820 01, B1830 01, B1835 01, B1840 01, B1845 01

--

Recline Rearward Switch Signal

1

1

B1735 01, B1740 01, B1745 01, B1750 01, B1755 01, B1760 01, B1815 01, B1820 01, B1830 01, B1835 01, B1840 01, B1845 01

--

Rear Vertical Up Switch Signal

1

1

B1735 01, B1740 01, B1745 01, B1750 01, B1755 01, B1760 01, B1815 01, B1820 01, B1830 01, B1835 01, B1840 01, B1845 01

--

Rear Vertical Down Switch Signal

1

1

B1735 01, B1740 01, B1745 01, B1750 01, B1755 01, B1760 01, B1815 01, B1820 01, B1830 01, B1835 01, B1840 01, B1845 01

--

  1. Power seat inoperative
  2. Lumbar support inoperative

Circuit/System Description

Battery voltage is supplied at all times to the seat and lumbar adjuster switches from the DPM 10A fuse located in the left rear fuse block. When the switches are pressed, they send a 12-volt signal through the switch signal circuits to the memory seat module (MSM). The MSM then commands the seat or lumbar motors to move in response to the switch signals.

Conditions for Running the DTC
    • DTC B1327 must not be present.
    • Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC
    • The MSM will set these DTCs when a short to voltage is detected on a switch signal circuit.
    • The MSM will set these DTCs if a seat switch circuit is active in one direction and a switch for the opposite direction is activated.
    • The MSM will set these DTCs if a seat adjuster switch is active for 30 seconds after a motor has reached the end of its travel.

Actions Taken When the DTC Sets
    • The motor associated with the inoperative switch adjuster signal circuit will be disabled for both directions.
    • The memory seat functions for the seat will be disabled.
    • The MSM will respond to any other switch adjuster signal that has not set a DTC.

Conditions for Clearing the DTCs
    • The condition responsible for setting the DTC no longer exists.
    • A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.

Diagnostic Aids

The memory seat module (MSM) is also referred to as the driver position module (DPM) in certain scan tool menus.

Reference Information

Schematic Reference

Driver Seat 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 Verification
  1. Ignition ON, observe all scan tool Driver Position Module seat switch parameters while pressing and releasing each seat directional switch. The reading should change between Inactive and Active.
  2. Ignition ON, observe all scan tool Driver Position Module lumbar switch parameters while pressing and releasing each lumbar directional switch. The reading should change between Inactive and Active.

Circuit/System Testing

B1735 01, B1740 01, B1745 01, B1750 01, B1755 01, B1760 01, B1815 01, B1820 01

  1. Ignition OFF, disconnect the harness connector at the driver seat adjuster switch.
  2. Ignition ON, verify the scan tool seat switch parameters listed below are Inactive.
    3. • Front Vertical Upward Switch
    • Rear Vertical Upward Switch
    • Horizontal Forward Switch
    • Recline Forward Switch
    • Front Vertical Downward Switch
    • Rear Vertical Downward Switch
    • Horizontal Rearward Switch
    • Recline Rearward Switch
    ⇒If not the specified value, test the appropriate switch signal circuit listed below for a short to voltage. If the circuit tests normal, replace the MSM.
    • Front vertical upward switch terminal K
    • Front vertical downward switch terminal J
    • Rear vertical upward switch terminal H
    • Rear vertical downward switch terminal G
    • Horizontal forward switch terminal D
    • Horizontal rearward switch terminal C
    • Recline forward switch terminal F
    • Recline rearward switch terminal A
  3. If all circuits test normal, test or replace the seat adjuster switch.

B1830 01, B1835 01, B1840 01, B1845 01

  1. Ignition OFF, disconnect the harness connector at the lumbar switch.
  2. Ignition ON, verify the scan tool lumbar switch parameters listed below are Inactive.
    3. • Lumbar Upward Switch
    • Lumbar Forward Switch
    • Lumbar Downward Switch
    • Lumbar Rearward Switch
    ⇒If not the specified value, test the appropriate switch signal circuit listed below for a short to voltage. If the circuit tests normal, replace the MSM.
    • Lumbar upward switch terminal F
    • Lumbar downward switch terminal J
    • Lumbar forward switch terminal C
    • Lumbar rearward switch terminal B
  3. If all circuits test normal, test or replace the lumbar switch.

Component Testing

Seat Adjuster Switch

  1. Ignition OFF, disconnect the harness connector at the seat adjuster switch.
  2. Test for infinite resistance between each seat direction signal terminal listed below and the B+ terminal E with the switch in the open position.
    3. • Front vertical upward switch terminal K
    • Front vertical downward switch terminal J
    • Rear vertical upward switch terminal H
    • Rear vertical downward switch terminal G
    • Horizontal forward switch terminal D
    • Horizontal rearward switch terminal C
    • Recline forward switch terminal F
    • Recline rearward switch terminal A
    ⇒If not the specified value, replace the seat adjuster switch.
  3. Test for less than 1 ohm between each seat direction signal terminal listed below and the B+ terminal E with the switch in the closed position.
    4. • Front vertical upward switch terminal K
    • Front vertical downward switch terminal J
    • Rear vertical upward switch terminal H
    • Rear vertical downward switch terminal G
    • Horizontal forward switch terminal D
    • Horizontal rearward switch terminal C
    • Recline forward switch terminal F
    • Recline rearward switch terminal A
    ⇒If greater than the specified range, replace the seat adjuster switch.

Lumbar Switch

  1. Ignition OFF, disconnect the harness connector at the lumbar adjuster switch.
  2. Test for infinite resistance between each lumbar direction signal terminal listed below and the B+ terminal G with the switch in the open position.
    3. • Lumbar upward switch terminal F
    • Lumbar downward switch terminal J
    • Lumbar forward switch terminal C
    • Lumbar rearward switch terminal B
    ⇒If not the specified value, replace the lumbar adjuster switch.
  3. Test for less than 1 ohm between each lumbar direction signal terminal listed below and the B+ terminal G with the switch in the closed position.
    4. • Lumbar upward switch terminal F
    • Lumbar downward switch terminal J
    • Lumbar forward switch terminal C
    • Lumbar rearward switch terminal B
    ⇒If greater than the specified range, replace the lumbar adjuster switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Power Seat Switch Replacement
    •  Lumbar Switch Replacement
    •  Control Module References for MSM replacement, setup, and programming