Buick Regal: DTC B1735, B1740, B1745, B1750, B1755, B1760, B1815, or B1820 (Driver Seat)

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

Seat Front Up Switch Circuit

DTC B1740

Seat Front Down Switch Circuit

DTC B1745

Seat Rear Up Switch Circuit

DTC B1750

Seat Rear Down Switch Circuit

DTC B1755

Seat Assembly Forward Switch Circuit

DTC B1760

Seat Assembly Rearward Switch Circuit

DTC B1815

Seat Recline Forward Switch Circuit

DTC B1820

Seat Recline Rearward Switch Circuit

For symptom byte information refer to Symptom Byte List.

Diagnostic Fault Information

1. Power seat is inoperative

Circuit/System Description

The seat memory control module supplies a reference voltage to each signal circuit of the driver seat adjuster switch. When the power seat switches are pressed, the appropriate signal circuit from the seat memory control module is pulled low through the switch contacts indicating the power seat command.

The seat memory control module then commands the driver seat to move in response to the switch signals.

Conditions for Running the DTC

• DTC B1325 must not be present.
• Module battery voltage must be between 9 - 16 V.

Conditions for Setting the DTC

• If a seat or lumbar switch circuit is active in one direction and the switch for the opposite direction is pressed, this DTC will set.
• A short to ground on a switch signal circuit.

Action Taken When the DTC Sets

• A motor output driven in response to a switch considered failed, is deactivated for both directions.
• All memory recall commands are ignored.
• The seat memory control module will respond to any other switch signal that has not set a DTC.

Conditions for Clearing the DTC

• The current DTC will clear and set the DTC to history, when the fault is no longer present and the ignition is cycled OFF then back to ACC or RUN.
• The history DTC will clear after 40 consecutive fault-free ignition cycles have occurred.

Diagnostic Aids

• If one of the switch signal circuits is shorted to ground, multiple DTCs will set.
• If a switch is stuck in one direction and the switch is pressed in the opposite direction, a single DTC will set.

Reference Information

Schematic Reference

Driver Seat Wiring Schematics

Connector End View Reference

Component Connector End View Index

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.

2. Verify the scan tool seat switch parameters listed below change between Inactive and Forward/Rearward or UP/Down when pressing the appropriate seat directional switch.

• Driver Seat Cushion Front Vertical Switch
• Driver Seat Cushion Rear Vertical Switch
• Driver Seat Horizontal Switch
• Driver Seat Back Switch
• If the parameter does not change

Refer to Circuit/System Testing.

• Go to next step: If the parameter changes

3. All OK.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the S64D Seat Adjuster Switch - Driver.

2. Clear present DTCs to enable system.

3. Verify that all scan tool driver seat switch parameters listed below are Inactive:

• Driver Seat Cushion Front Vertical Switch
• Driver Seat Cushion Rear Vertical Switch
• Driver Seat Horizontal Switch
• Driver Seat Back Switch
• If not Inactive

1. Ignition OFF, disconnect the X5 harness connector at the K40D Seat Memory Control Module - Driver, ignition ON.
2. Test for infinite resistance between the appropriate signal circuit terminal listed below and ground:
   • Front vertical up switch terminal A
   • Front vertical down switch terminal K
   • Rear vertical up switch terminal F
   • Rear vertical down switch terminal J
   • Horizontal forward switch terminal D
   • Horizontal rearward switch terminal C
   • Recline forward switch terminal H
   • Recline rearward switch terminal G
   • If less than infinite resistance, repair the short to ground on the circuit.
   • If infinite resistance, replace the K40D Seat Memory Control Module - Driver.

• Go to next step: If Inactive

4. Install a 3 A fused jumper wire between the appropriate signal circuit terminal listed below and the ground circuit terminal E.

• Front vertical up switch terminal A
• Front vertical down switch terminal K
• Rear vertical up switch terminal F
• Rear vertical down switch terminal J
• Horizontal forward switch terminal D
• Horizontal rearward switch terminal C
• Recline forward switch terminal H
• Recline rearward switch terminal G

5. Verify the appropriate scan tool seat switch parameter is Forward/Rearward or UP/Down.

• If not Forward/Rearward or UP/Down

1. Ignition OFF, disconnect the X5 harness connector at the K40D Seat Memory Control Module - Driver, ignition ON.
2. Test for less than 1 V between the signal circuit terminal and ground.
   • If 1 V or greater, repair the short to voltage on the circuit.
   • Go to next step: If less than 1 V
3. Ignition OFF.
4. Test for less than 2 Ω in the signal circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the K40D Seat Memory Control Module - Driver.

• Go to next step: If Forward/Rearward or UP/Down

6. Test or replace the S64D Seat Adjuster Switch - Driver.

Component Testing

Seat Adjuster Switch Test

1. Ignition OFF, disconnect the harness connector at the S64D Seat Adjuster Switch - Driver.

2. Test for infinite resistance between the ground terminal E and each signal terminal with the switch in the open position.

• If less than infinite resistance

Replace the S64D Seat Adjuster Switch - Driver.

• Go to next step: If infinite resistance

3. Test for less than 2 Ω between the ground terminal E and each signal terminal with the appropriate switch in the closed position.

• If 2 Ω or greater

Replace the S64D Seat Adjuster Switch - Driver.

• Go to next step: If less than 2 Ω

4. All OK.

Repair Instructions

• Perform the Diagnostic Repair Verification after completing the repair.

  Driver or Passenger Seat Adjuster Switch Replacement

• Control Module References for K40D Seat Memory Control Module - Driver replacement, programming and setup

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