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Tahoe / Yukon Service Manual

Lumbar_Bolster_Massage Malfunction (4-Way Passenger Without AKE)

Lumbar/Bolster/Massage Malfunction (4-Way Passenger 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

Circuit Number Circuit Function Short to Ground Open/High Resistance Short to Voltage Signal Performan
3940 B+ 1 1 — —
1068 Signal 1 1 1 —
4890 Control 1 1 2 —
2194 Low Reference — 1 — —
1250 Ground — 1 — —
1. The passenger seat lumbar support functions are inoperative 2. The seat lumbar support pump is always ON

Circuit/System Description The K104 Front Seat Bladder Control Module supplies the S65 Front Seat Lumbar Switch with a signal and low reference circuits. When a lumbar switch is pressed, the signal circuit from the K104 Front Seat Bladder Control Module is pulled low through the switch contacts and series of resistors indicating the lumbar request. In response to this request, the K104 Front Seat Bladder Control Module energizes its internal inflate/deflate solenoid and applies battery voltage through the control circuit to the G31 Front Seat Back Lumbar Pump. The pump runs to inflate the appropriate support bladder until the switch is released. Reference Information Schematic Reference Driver Seat Schematics Passenger Seat Schematics Connector End View Reference Master Electrical Component List Description and Operation Lumbar Support/Massage Description and Operation Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs Circuit/System Verification

  1. Ignition/Vehicle in Service Mode.
  2. Verify that no DTCs are set. ⇒ If any DTC is set Refer to Diagnostic Trouble Code (DTC) List - Vehicle. ⇓ If no DTCs are set
  3. Operate the seat lumbar UP / DOWN / FORWARD / REARWARD. Verify each function operates. ⇒ If any of the lumbar functions do not operate Refer to: Circuit/System Testing ⇓ If all of the lumbar functions operate
  4. A fault is currently not present and may be an intermittent condition. Circuit/System Testing
  5. Ignition/Vehicle OFF, disconnect the connector at the K104PP Front Seat Bladder Control Module - Passenger Primary. It may take up to 2 min for all vehicle systems to power down.
  6. Test for less than 10 Ω between the ground circuit terminal 4 and ground. ⇒ If 10 Ω or greater 2.1. Test the circuit 1250 for an open/high resistance. ⇒ If an open/high resistance is found, repair the fault on the circuit. ⇓ If an open/high resistance is not found 2.2. Repair the open/high resistance in the ground connection. ⇓ If less than 10 Ω
  7. Ignition/Vehicle in Service Mode.
  8. Verify a test lamp illuminates between the B+ circuit terminal 1 and ground. ⇒ If the test lamp does not illuminate 4.1. Test circuit 3940 for a short to ground. ⇒ If a short to ground is found, repair the fault on the circuit. ⇓ If a short to ground is not found 4.2. Test circuit 3940 for an open/high resistance. ⇒ If an open/high resistance is found, repair the fault on the circuit. ⇓ If an open/high resistance is not found 4.3. Verify the fuse is OK and there is voltage at the fuse. ⇓ If the test lamp illuminates
  9. Ignition/Vehicle OFF, connect the connector at the K104PP Front Seat Bladder Control Module - Passenger Primary and disconnect the connector at the S65P Front Seat Lumbar Switch – Passenger.
  10. Test for less than 10 Ω between the low reference circuit terminal 4 and ground. ⇒ If 10 Ω or greater 6.1. Test circuit 2194 for an open/high resistance. ⇒ If an open/high resistance is found, repair the fault on the circuit. ⇓ If an open/high resistance is not found 6.2. Replace the K104PP Front Seat Bladder Control Module - Passenger Primary. ⇓ If less than 10 Ω
  11. Ignition/Vehicle in Service Mode.
  12. Test for 4.8–5.2 V between the signal circuit terminal 3 and ground. ⇒ If less than 4.8 V 8.1. Test circuit 1068 for a short to ground. ⇒ If a short to ground is found, repair the fault on the circuit. ⇓ If a short to ground is not found 8.2. Test circuit 1068 for an open/high resistance. ⇒ If an open/high resistance is found, repair the fault on the circuit. ⇓ If an open/high resistance is not found 8.3. Replace the K104PP Front Seat Bladder Control Module - Passenger Primary. ⇒ If greater than 5.2 V 8.1. Test circuit 1068 for a short to voltage. ⇒ If a short to voltage is found, repair the fault on the circuit. ⇓ If a short to voltage is not found 8.2. Replace the K104PP Front Seat Bladder Control Module - Passenger Primary. ⇓ If between 4.8–5.2 V
  13. Ignition/Vehicle OFF, connect the connector at the S65P Front Seat Lumbar Switch – Passenger and disconnect the connector at the K104PP Front Seat Bladder Control Module - Passenger Primary.
  14. Connect a DDM between the signal circuit terminal 6 and the low reference circuit terminal 5.
  15. Test for the resistance values listed below while pressing the appropriate S65P Front Seat Lumbar Switch – Passenger. 520–575 Ω for the lumbar forward switch 1325–1465 Ω for the lumbar rearward switch 2680–2965 Ω for the lumbar up switch 5340–5905 Ω for the lumbar down switch ⇒ If not between the specified values Test or replace the S65P Front Seat Lumbar Switch – Passenger. ⇓ If between the specified values
  16. Ignition/Vehicle OFF, connect the connector at the K104PP Front Seat Bladder Control Module - Passenger Primary and disconnect the connector at the G31P Front Seat Back Lumbar Pump – Passenger.
  17. Test for less than 10 Ω between the ground circuit terminal 2 and ground. ⇒ If 10 Ω or greater 13.1. Test the circuit 1250 for an open/high resistance. ⇒ If an open/high resistance is found, repair the fault on the circuit. ⇓ If an open/high resistance is not found 13.2. Repair the open/high resistance in the ground connection. ⇓ If less than 10 Ω
  18. Connect a test lamp between the control circuit terminal 1 and ground.
  19. Ignition/Vehicle in Service Mode.
  20. Verify the test lamp turns ON and OFF when pressing and releasing the lumbar forward switch. ⇒ If the test lamp remains OFF 16.1. Test circuit 4890 for a short to ground. ⇒ If a short to ground is found, repair the fault on the circuit. ⇓ If a short to ground is not found 16.2. Test circuit 4890 for an open/high resistance. ⇒ If an open/high resistance is found, repair the fault on the circuit. ⇓ If an open/high resistance is not found 16.3. Replace the K104PP Front Seat Bladder Control Module - Passenger Primary. ⇒ If the test lamp is always ON 16.1. Test circuit 4890 for a short to voltage. ⇒ If a short to voltage is found, repair the fault on the circuit. ⇓ If a short to voltage is not found 16.2. Replace the K104PP Front Seat Bladder Control Module - Passenger Primary. ⇓ If the test lamp turns ON and OFF
  21. Replace the G31P Front Seat Back Lumbar Pump – Passenger. Component Testing Front Seat Lumbar Switch
  22. Ignition OFF, disconnect the connector at the appropriate S65 Front Seat Lumbar Switch.
  23. Test for less than infinite resistance between the signal terminal 3 and the low reference terminal 4 with the switch in the open position. ⇒ If infinite resistance Replace the S65 Front Seat Lumbar Switch. ⇓ If less than infinite resistance
  24. Test for 520–575 Ω between the signal terminal 3 and the low reference terminal 4 while pressing the lumbar forward switch. ⇒ If not between 520–575 Ω Replace the S65 Front Seat Lumbar Switch. ⇓ If between 520–575 Ω
  25. Test for 1325–1465 Ω between the signal terminal 3 and the low reference terminal 4 while pressing the lumbar rearward switch. ⇒ If not between 1325–1465 Ω Replace the S65 Front Seat Lumbar Switch. ⇓ If between 1325–1465 Ω
  26. Test for 2680–2965 Ω between the signal terminal 3 and the low reference terminal 4 while pressing the lumbar up switch. ⇒ If not between 2680–2965 Ω Replace the S65 Front Seat Lumbar Switch. ⇓ If between 2680–2965 Ω
  27. Test for 5340–5905 Ω between the signal terminal 3 and the low reference terminal 4 while pressing the lumbar down switch. ⇒ If not between 5340–5905 Ω Replace the S65 Front Seat Lumbar Switch. ⇓ If between 5340–5905 Ω
  28. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. Front Seat Lumbar Switch Replacement Front Seat Back Lumbar Replacement