Buick Regal: Lumbar/Bolster/Massage Malfunction (AVK without AF6 or AVU without
AKE)
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. The seat lumbar support functions are inoperative
2. The seat lumbar support pump is always ON
Circuit/System Description
The seat lumbar support valve assembly supplies the seat lumbar support
switch with a signal and low
reference circuits. When a lumbar switch is pressed, the signal circuit from the
seat lumbar support valve
assembly is pulled low through the switch contacts and series of resistors
indicating the lumbar support
request. In response to this request, the lumbar adjuster valve assembly
energizes its internal inflate
solenoid and applies battery voltage through the lumbar support pump control
circuit to the pump. The
pump runs to inflate the appropriate support bladder until the switch is
released.
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
Circuit/System Testing
1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector
at the appropriate seat
lumbar support valve assembly listed below. It may take up to 2 min for all
vehicle systems to
power down.
- Q51D Seat Lumbar Support Valve Assembly - Driver
- Q51P Seat Lumbar Support Valve Assembly - Passenger
2. Test for less than 10 Ω between the ground circuit terminal 2 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. Verify a test lamp illuminates between the B+ circuit terminal 1 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 short 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 not open and there is voltage
at the fuse.
- Go to next step: If the test lamp illuminates
5. Ignition OFF and all vehicle systems OFF, connect the harness connector at
the Q51 Seat Lumbar
Support Valve Assembly and disconnect the harness connector at the S65 Seat
Lumbar Support
Switch. It may take up to 2 min for all vehicle systems to power down.
6. Test for less than 10 Ω between the low reference circuit terminal 1 and
ground.
- Ignition OFF.
- Test for less than 2 Ω in the low reference circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit
- If less than 2 Ω, test or replace the Q51 Seat Lumbar Support Valve
Assembly.
- Go to next step: If less than 10 Ω
7. Ignition ON.
8. Test for 4.8 - 5.2 V between the signal circuit terminal 2 and ground.
- Ignition OFF, disconnect the harness connector at the Q51 Seat Lumbar
Support Valve
Assembly.
- 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, test or replace the Q51 Seat Lumbar Support Valve
Assembly.
- Ignition OFF, disconnect the harness connector at the Q51 Seat Lumbar
Support Valve
Assembly, 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, test or replace the Q51 Seat Lumbar Support Valve
Assembly.
- Go to next step: If between 4.8 - 5.2 V
9. Ignition OFF, connect the harness connector at the S65 Seat Lumbar Support
Switch and
disconnect the harness connector at the Q51 Seat Lumbar Support Valve Assembly.
10. Connect a DDM between the signal circuit terminal 4 and the low reference
circuit terminal 5.
11. Test for the resistance values listed below while pressing the appropriate
S65 Seat Lumbar
Support Switch.
- 146 - 178 Ω for the lumbar forward switch
- 459 - 561 Ω for the lumbar rearward switch
- 1134 - 1386 Ω for the lumbar down switch
- 3024 - 3696 Ω for the lumbar up switch
- If not between the specified values
Test or replace the S65 Seat Lumbar Support Switch.
- Go to next step: If between the specified values
12. Ignition OFF, connect the harness connector at the Q51 Seat Lumbar
Support Valve Assembly and
disconnect the harness connector at the G31 Seat Lumbar/Bolster Pump.
13. Test for less than 10 Ω between the ground circuit terminal 2 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
14. Connect a test lamp between the control circuit terminal 1 and ground,
ignition ON.
15. Verify the test lamp turns ON and OFF when pressing and releasing the lumbar
forward switch.
- If the test lamp remains OFF
- Ignition OFF, remove the test lamp, disconnect the harness connector at
the Q51 Seat
Lumbar Support Valve Assembly.
- Test for infinite resistance between the 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 the control circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit
- If less than 2 Ω, test or replace the Q51 Seat Lumbar Support Valve
Assembly.
- If the test lamp is always ON
- Ignition OFF, remove the teat lamp, disconnect the harness connector at
the Q51 Seat
Lumbar Support Valve Assembly, ignition ON.
- Test for less than 1 V between the control circuit and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, replace the Q51 Seat Lumbar Support Valve
Assembly.
- Go to next step: If the test lamp turns ON and OFF
16. Test or replace the G31 Seat Lumbar/Bolster Pump.
Component Testing
Seat Lumbar Support Switch
1. Ignition OFF, disconnect the harness connector at the appropriate S65 Seat
Lumbar Support
Switch.
2. Test for infinite resistance between the signal terminal 2 and the low
reference 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 146 - 178 Ω between the signal terminal 2 and the low reference
terminal 1 while pressing
the lumbar forward switch.
- If not between 146 - 178 Ω
Replace the S65 Seat Lumbar Support Switch.
- Go to next step: If between 146 - 178 Ω
4. Test for 459 - 561 Ω between the signal terminal 2 and the low reference
terminal 1 while pressing
the lumbar rearward switch.
- If not between 459 - 561 Ω
Replace the S65 Seat Lumbar Support Switch.
- Go to next step: If between 459 - 561 Ω
5. Test for 1134 - 1386 Ω between the signal terminal 2 and the low reference
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
6. Test for 3.02k - 3.7 kΩ between the signal terminal 2 and the low
reference 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
7. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
- Driver or Passenger Seat Lumbar Control Switch Replacement
- Front Seat Back Lumbar Replacement (2 Way) or Front Seat Back Lumbar
Replacement
(GS) or Front Seat Back Lumbar Replacement (4 Way)
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 prior to using this diagnostic
procedure: Refer to Diagnostic System
Check - Vehicle
Review the description of Strategy Based Diagnosis: Refer to Strategy
Based Diagnosis
An overview of each diagnostic category can be found here: R