Buick Regal: DTC B183B or B183C
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 B183B
Seat Lumbar Support Switch Signal Circuit
DTC B183C
Seat Bolster/Massage Switch Signal Circuit
For symptom byte information refer to Symptom Byte List.
Diagnostic Fault Information
1. The seat lumbar support function is inoperative.
2. The seat side bolster/massage function is inoperative.
Circuit/System Description
Ground is supplied to the seat lumbar support and the seat back side bolster
switches. Each switch is
also supplied with a 5 V reference and signal circuits from the seat memory
control module. The
reference voltage is applied to a resistive network internal to the switches.
When a switch is pressed, the
output of the resistive network results in a voltage drop on the signal circuit
to the seat memory control
module indicating the lumbar, bolster, or massage request. In response to this
signal, the seat memory
control module sends a LIN serial data message to the seat bolster memory
control module commanding
it to perform the required pneumatic movements.
Conditions for Running the DTC
- DTC B1327 must not be present.
- Battery voltage must be between 9 - 16 V.
Conditions for Setting the DTC
B183B 06
If the seat memory control module detects a short to ground or an open in the
seat lumbar support switch
signal circuit this DTC will set.
B183B 08
If the seat memory control module detects an invalid signal on the seat
lumbar support switch signal
circuit this DTC will set.
B183B 59
The seat memory control module detects a stuck lumbar support switch for a
given amount of time.
B183C 06
If the seat memory control module detects a short to ground or an open in the
seat bolster/massage
switch signal circuit this DTC will set.
B183C 08
If the seat memory control module detects an invalid signal on the seat
bolster/massage switch signal
circuit this DTC will set.
B183C 59
The seat memory control module detects a stuck seat bolster or massage switch
for a given amount of
time.
Actions Taken When the DTC Sets
B183B 06, B183B 08, or B183B 59
- Current and history DTCs are set.
- All seat lumbar support commands and are ignored.
B183C 06, B183C 08, or B183C 59
- Current and history DTCs are set.
- All seat bolster and massage commands and are ignored.
Conditions for Clearing the DTCs
- The DTC automatically clears when the switch circuit setting the DTC is
no longer active.
- A history DTC will clear once 50 consecutive fault-free ignition cycles
have occurred.
Reference Information
Schematic Reference
- Driver Seat Wiring Schematics
- Passenger Seat Wiring Schematics
Connector End View Reference
Component Connector End View Index
Description and Operation
Lumbar Support Description and Operation (With Memory Seat A44/A45) or
Lumbar Support
Description and Operation (Without Memory Seat A44/A45)
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 DTC B183B 59 is not set as a current DTC.
- If the DTC is set current
Replace the S65 Seat Lumbar Support Switch.
- Go to next step: If the DTC is not set current
3. Verify DTC B183C 59 is not set as a current DTC.
- If the DTC is set current
Replace the S66 Seat Back Side Bolster Adjuster Switch.
- Go to next step: If the DTC is not set current
4. Verify DTC B183B 06 or B183B 08 is not set.
Refer to Circuit/System Testing - DTC B183B Lumbar Switch Circuit Test.
- Go to next step: If either DTC is not set
5. Verify DTC B183C 06 or B183C 08 is not set.
Refer to Circuit/System Testing - DTC B183C Seat Back Side Bolster Switch
Circuit
Test.
- Go to next step: If either DTC is not set
6. All OK.
Circuit/System Testing
DTC B183B Lumbar Switch Circuit Test
1. Ignition OFF, disconnect the harness connector at the appropriate seat
lumbar support switch
listed below. It may take up to 2 min for all vehicle systems to power down.
- S65D Seat Lumbar Support Switch - Driver
- S65P Seat Lumbar Support Switch - Passenger
2. Test for less than 10 Ω between the ground circuit terminal 1 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 ON.
4. Test for 4.8 - 5.2 V between the 5 V reference circuit terminal 3 and ground.
- Ignition OFF, disconnect the X5 harness connector at the K40 Seat Memory
Control
Module.
- Test for infinite resistance between the 5 V reference 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 the 5 V reference circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K40 Seat Memory Control Module.
- Ignition OFF, disconnect the X5 harness connector at the K40 Seat Memory
Control
Module, ignition ON.
- Test for less than 1 V between the 5 V reference circuit and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, replace the K40 Seat Memory Control Module.
- Go to next step: If between 4.8 - 5.2 V
5. Test for less than 1 V between the signal circuit terminal 2 and ground.
- Ignition OFF, disconnect the X5 harness connector at the K40 Seat Memory
Control
Module, 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.
- If less than 1 V, replace the K40 Seat Memory Control Module.
- Go to next step: If less than 1 V
NOTE: With the seat lumbar support switch disconnected, DTC B183B with
symptom byte 06 may already be set. However, the purpose of this
test is to verify DTC B183B will set with symptom byte 08 when the
signal circuit is shorted to voltage.
6. Install a 3 A fused jumper wire between the 5 V reference circuit terminal
3 and the signal circuit
terminal 2.
7. Verify DTC B183B 08 is set.
- If DTC B183B 08 is not set
- Ignition OFF, disconnect the X5 harness connector at the K40 Seat Memory
Control
Module.
- Test for infinite resistance between the signal 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 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 K40 Seat Memory Control Module.
- Go to next step: If DTC B183B 08 is set
8. Test or replace the S65 Seat Lumbar Support Switch.
DTC B183C Seat Back Side Bolster Switch Circuit Test
1. Ignition OFF, disconnect the harness connector at the seat back side
bolster adjuster switch listed
below. It may take up to 2 min for all vehicle systems to power down.
- S66D Seat Back Side Bolster Adjuster Switch - Driver
- S66P Seat Back Side Bolster Adjuster Switch - Passenger
2. Test for less than 10 Ω between the ground circuit terminal 1 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 ON.
4. Test for 4.8 - 5.2 V between the 5 V reference circuit terminal 3 and ground.
- Ignition OFF, disconnect the X5 harness connector at the K40 Seat Memory
Control
Module.
- Test for infinite resistance between the 5 V reference 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 the 5 V reference circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K40 Seat Memory Control Module.
- Ignition OFF, disconnect the X5 harness connector at the K40 Seat Memory
Control
Module, ignition ON.
- Test for less than 1 V between the 5 V reference circuit and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, replace the K40 Seat Memory Control Module.
- Go to next step: If between 4.8 - 5.2 V
5. Test for less than 1 V between the signal circuit terminal 2 and ground.
- Ignition OFF, disconnect the X5 harness connector at the K40 Seat Memory
Control
Module, 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.
- If less than 1 V, replace the K40 Seat Memory Control Module.
- Go to next step: If less than 1 V
NOTE: With the seat back side bolster adjuster switch disconnected, DTC
B183C with symptom byte 06 may already be set. However, the
purpose of this test is to verify DTC B183C will set with symptom
byte 08 when the signal circuit is shorted to voltage.
6. Install a 3 A fused jumper wire between the 5 V reference circuit terminal
3 and the signal circuit
terminal 2.
7. Verify DTC B183C 08 is set.
- If DTC B183C 08 is not set
- Ignition OFF, disconnect the X5 harness connector at the K40 Seat Memory
Control
Module.
- Test for infinite resistance between the signal 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 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 K40 Seat Memory Control Module.
- Go to next step: If DTC B183C 08 is set
8. Test or replace the S66 Seat Back Side Bolster Adjuster Switch.
Component Testing
Seat Lumbar Support Switch
1. Ignition OFF, disconnect the harness connector at the S65 Seat Lumbar
Support Switch.
2. Test for infinite resistance between the signal terminal 2 and the ground
terminal 1 with the switch
in the open position.
- If less than infinite resistance
Replace the S65 Seat Lumbar Support Switch.
- Go to next step: If infinite resistance
3. Test for 252 - 308 Ω between the signal terminal 2 and the 5 V reference
terminal 3.
- If not between 252 - 308 Ω
Replace the S65 Seat Lumbar Support Switch.
- Go to next step: If between 252 - 308 Ω
4. Test for 146 - 178 Ω between the signal terminal 2 and the ground terminal
1 while pressing the
lumbar rearward switch.
- If not between 146 - 178 Ω
Replace the S65 Seat Lumbar Support Switch.
- Go to next step: If between 146 - 178 Ω
5. Test for 459 - 561 Ω between the signal terminal 2 and the ground terminal
1 while pressing the
lumbar forward switch.
- If not between 459 - 561 Ω
Replace the S65 Seat Lumbar Support Switch.
- Go to next step: If between 459 - 561 Ω
6. Test for 1134 - 1386 Ω between the signal terminal 2 and the ground
terminal 1 while pressing the
lumbar down switch.
- If not between 1134 - 1386 Ω
Replace the S65 Seat Lumbar Support Switch.
- Go to next step: If between 1134 - 1386 Ω
7. Test for 3.02k - 3.7 kΩ between the signal terminal 2 and the ground
terminal 1 while pressing the
lumbar up switch.
- If not between 3.02k - 3.7 kΩ
Replace the S65 Seat Lumbar Support Switch.
- Go to next step: If between 3.02k - 3.7 kΩ
8. All OK.
Seat Back Side Bolster Switch
1. Ignition OFF, disconnect the harness connector at the S66 Seat Back Side
Bolster Adjuster
Switch.
2. Test for infinite resistance between the signal terminal 2 and the ground
terminal 1 with the switch
in the open position.
- If less than infinite resistance
Replace the S66 Seat Back Side Bolster Adjuster Switch.
- Go to next step: If infinite resistance
3. Test for 252 - 308 Ω between the signal terminal 2 and the 5 V reference
terminal 3.
- If not between 252 - 308 Ω
Replace the S66 Seat Back Side Bolster Adjuster Switch.
- Go to next step: If between 252 - 308 Ω
4. Test for 459 - 561 Ω between the signal terminal 2 and the ground terminal
1 while pressing the
seat back side bolster inflate switch.
- If not between 459 - 561 Ω
Replace the S66 Seat Back Side Bolster Adjuster Switch.
- Go to next step: If between 459 - 561 Ω
5. Test for 1134 - 1386 Ω between the signal terminal 2 and the ground
terminal 1 while pressing the
seat back side bolster deflate switch.
- If not between 1134 - 1386 Ω
Replace the S66 Seat Back Side Bolster Adjuster Switch.
- Go to next step: If between 1134 - 1386 Ω
6. Test for 3.02k - 3.7 kΩ between the signal terminal 2 and the ground
terminal 1 while pressing the
massage switch.
- If not between 3.02k - 3.7 kΩ
Replace the S66 Seat Back Side Bolster Adjuster Switch.
- Go to next step: If between 3.02k - 3.7 kΩ
7. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
- Driver or Passenger Seat Lumbar Control Switch Replacement
- Control Module References for K40D Seat Memory Control Module - Driver
or K40P Seat
Memory Control Module - Passenger replacement, programming, and setup
READ NEXT:
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.
Diag
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.
Diag
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.
Diag
SEE MORE:
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
DT
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
DT