Buick Regal: Power Seat Malfunction (Passenger Seat with Memory A44)
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.
Diagnostic Fault Information
1. All power seat motors are inoperative
2. The seat front vertical motor is inoperative
3. The seat horizontal motor is inoperative
4. The seat rear vertical motor is inoperative
5. The seat recline motor is inoperative
Circuit/System Description
Battery voltage is supplied at all times to the seat memory control module
through a 5 A fuse located in
the underhood fuse block. This voltage is used by the module for logic power.
Battery positive voltage is
also supplied at all times to the seat memory control module through a 30 A fuse
also located in the
underhood fuse block. This voltage is connected to a power rail internal to the
seat memory control
module and is used to drive all power seat motors. Each seat motor is controlled
by the seat memory
control module by applying power and ground through the control circuits to the
motor.
All motors are reversible. For example, when the seat switch is operated to move
the entire seat forward,
the switch signal circuit from the seat memory control module is pulled low
indicating the entire seat
forward command. In response to this signal, the seat memory control module
applies battery voltage
through the seat horizontal motor forward control circuit and ground through the
seat horizontal motor
rearward control circuit to the motor. The motor runs to drive the entire seat
forward until the switch is
released. Moving the entire seat rearward works similarly to moving the entire
seat forward, except that
battery positive voltage and ground are applied on the opposite circuits causing
the motor to run in the
opposite direction. All power seat motors are powered this way.
Reference Information
Schematic Reference
Passenger 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 switch.
- Passenger Seat Horizontal Switch
- Passenger Seat Cushion Front Vertical Switch
- Passenger Seat Cushion Rear Vertical Switch
- Passenger Seat Back Switch
- If any parameter does not change
Refer to Circuit/System Testing - Seat Adjuster Switch Circuit Test
- Go to next step: If all parameters change
3. Verify the seat directional motors listed below operate when pressing the
appropriate seat switches
in both directions.
- M50P Seat Front Vertical Motor - Passenger
- M55P Seat Rear Vertical Motor - Passenger
- M51P Seat Horizontal Motor - Passenger
- M56P Seat Recline Motor - Passenger
- If any seat motor does not operate
Refer to Circuit/System Testing - Seat Motor Control Circuit Test.
- Go to next step: If all seat motors operate
4. All OK.
Circuit/System Testing
Seat Adjuster Switch Circuit Test
1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector
at the S64P Seat
Adjuster Switch - Passenger. It may take up to 2 min for all vehicle systems to
power down.
2. Test for less than 10 Ω between the ground circuit terminal E and ground.
- Ignition Off.
- Test for less than 2 Ω in the ground circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, repair the open/high resistance in the ground
connection.
- Go to next step: If less than 10 Ω
3. Install a 3 A fused jumper wire between the ground circuit terminal E and
the appropriate signal
circuit terminal listed below, ignition ON.
- Front vertical up switch terminal K
- Front vertical down switch terminal A
- Rear vertical up switch terminal J
- Rear vertical down switch terminal F
- Horizontal forward switch terminal D
- Horizontal rearward switch terminal C
- Recline forward switch terminal H
- Recline rearward switch terminal G
4. Verify the appropriate scan tool seat switch parameter is Forward/Rearward
or UP/Down.
- If not Forward/Rearward or UP/Down
- Ignition OFF, disconnect the X5 harness connector at the K40P Seat
Memory Control
Module - Passenger, ignition ON.
- Test for less than 1 V between the signal circuit and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- Go to next step: If less than 1 V
- Ignition OFF.
- 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 K40P Seat Memory Control Module -
Passenger.
- Go to next step: If Forward/Rearward or UP/Down
5. Test or replace the S64P Seat Adjuster Switch - Passenger.
Seat Motor Control Circuit Test
1. Ignition OFF, disconnect the X2 harness connector at the K40P Seat Memory
Control Module -
Passenger.
2. Test for less than 10 Ω between ground circuit terminal 5 and ground.
- Ignition OFF.
- Test for less than 2 Ω in the ground circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, repair the open/high resistance in the ground
connection.
- Go to next step: If less than 10 Ω
3. Ignition OFF, disconnect the X1 harness connector at the K40P Seat Memory
Control Module -
Passenger, ignition ON.
4. Verify that a test lamp illuminates between the B+ circuit terminal 2 and
ground.
- If the test lamp does not illuminate.
- Ignition OFF, remove the test lamp.
- Test for infinite resistance between the B+ circuit and ground.
- If less than infinite resistance, repair the shot to ground on the
circuit.
- Go to next step: If infinite resistance.
- Test for less than 2 Ω in the B+ circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, verify the fuse is OK and there is voltage at the
fuse.
- Go to next step: If the test lamp illuminates.
5. Ignition OFF, connect the X1 and X2 harness connectors at the K40P Seat
Memory Control
Module - Passenger and disconnect the harness connector at the appropriate seat
motor listed
below:
- M50P Seat Front Vertical Motor - Passenger
- M55P Seat Rear Vertical Motor - Passenger
- M51P Seat Horizontal Motor - Passenger
- M56P Seat Recline Motor - Passenger
6. Connect a test lamp between control circuit terminal 1 and control circuit
terminal 3, ignition ON.
NOTE: Once a seat motor is commanded On using the scan tool, the seat
function may not work using the seat adjuster switch until you back
out of the scan tool Control Functions menu.
7. Verify the test lamp turns ON when commanding the seat motor in the
Up/Down or
Forward/Rearward states with a scan tool.
- If the test lamp remains OFF during either of the commands
- Ignition OFF, disconnect the X3 harness connector at the K40P Seat
Memory Control
Module - Passenger.
- Test for infinite resistance between each control circuit and ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- Go to next step: If infinite resistance
- Test for less than 2 Ω in each control circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K40P Seat Memory Control Module -
Passenger.
- Go to next step: If the test lamp turns ON during each of the
commands
8. Test or replace the seat motor.
Component Testing
Seat Adjuster Switch Test
1. Ignition OFF, disconnect the harness connector at the S64P Seat Adjuster
Switch - Passenger.
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 S64P Seat Adjuster Switch - Passenger.
- 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.
Replace the S64P Seat Adjuster Switch - Passenger.
- Go to next step: If less than 2 Ω
4. All OK.
Seat Motor
1. Ignition OFF, disconnect the harness connector at the appropriate seat
motor listed below:
- M50P Seat Front Vertical Motor - Passenger
- M55P Seat Rear Vertical Motor - Passenger
- M51P Seat Horizontal Motor - Passenger
- M56P Seat Recline Motor - Passenger
NOTE: When performing the following tests, make sure that the seat is
not
already in the position the test is attempting to produce.
2. Install a 30 A fused jumper wire between control terminal 1 and 12 V.
3. Momentarily install a jumper wire between control terminal 3 and ground. The
seat motor should
momentarily perform the appropriate FORWARD/ REARWARD/ UP/ DOWN function.
- If the motor does not perform the FORWARD/ REARWARD/ UP/ DOWN
function
Replace the seat motor.
- Go to next step: If the motor performs the FORWARD/ REARWARD/ UP/
DOWN
function
4. Reverse the jumper wires; the motor should perform FORWARD/ REARWARD/ UP/
DOWN
function.
- If the motor does not perform the FORWARD/ REARWARD/ UP/ DOWN
function
Replace the seat motor.
- Go to next step: If the motor performs the FORWARD/ REARWARD/ UP/
DOWN
function
5. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
- Driver or Passenger Seat Adjuster Switch Replacement
- Front Seat Tilt Adjuster Actuator Replacement
- Driver or Passenger Seat Vertical Adjuster Actuator Replacement
- Driver or Passenger Seat Recliner Actuator Replacement (Except GS) or
Driver or
Passenger Seat Recliner Actuator Replacement (GS)
- Control Module References for K40P Seat Memory Control Module -
Passenger replacement,
programming and setup
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When the condition is not currently present, but is indicated in DTC history,
the cause may be
in
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Control (ACC), it allows for selecting
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following gap. Read this entire
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When to Inspect the Engine Air
Cleaner/Filter
For intervals on changing and
inspecting the engine air cleaner/
filter.
How to Inspect the Engine Air
Cleaner/Filter
Do not start the engine or have the
engine running with the engine air
cleaner/filter housing open. Before
removing the engine air clean