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Tahoe / Yukon Service Manual

Lumbar_Bolster_Massage Malfunction (4-Way Driver or 4-Way Passenger With AKE)

Lumbar/Bolster/Massage Malfunction (4-Way Driver or 4- Way Passenger With 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 ce
3940 B+ U0210, U0261 U0210 — —
2240 B+ U0209, U0260 U0209 — —
3758 Serial Data U0209, U0260 U0209 U0209, U0260 —
4116 Serial Data U0210, U0261 U0210 U0210, U0261 —
2816 Signal 2 2 2 —
2818 Signal 1 1 1 —
2815 Low Reference — 2 2 —
2817 Low Reference — 1 1 —
2305 Control 1 1 1 —
2306 Control 2 2 2 —
4890 Control 2 2 2 —
4891 Control 1 1 1 —
1150 Ground — U0209 — —
1250 Ground — U0210 — —

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Circuit Number Circuit Function Short to Ground Open/High Resistance Short to Voltage Signal Performan
2. Passenger lumbar, bolster, and massage functions are inoperative

Circuit/System Description The S64 Front Seat Adjuster Switch supplies the S65 Front Seat Lumbar Switch with a signal and low reference circuits. When a lumbar support switch is pressed, the signal circuit from the S64  Front Seat Adjuster Switch is pulled low through the switch contacts and series of resistors indicating the lumbar support request. In response to this request, the S64 Front Seat Adjuster Switch sends a LIN serial data message to the K40 Seat Adjuster Memory Module indicating the requested lumbar, bolster, or massage request. The K40 Seat Adjuster Memory Module then sends a LIN serial data message to the K104 Front Seat Bladder Control Module commanding it to perform the required pneumatic movements. The K104 Front Seat Bladder Control Module contains the electronic circuitry for executing the commanded pneumatic seat adjustments, air direction solenoids, pressure sensors for storing air bladder pressures, and outputs which supplies battery power and a low side drive pulse width modulated (PWM) signal to the external seat air pump motor when any of the air bladders require inflating. 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 Scan Tool Reference Control Module References for scan tool information Circuit/System Verification

  1. Ignition/Vehicle in Service Mode.
  2. Verify no DTCs are set. ⇒ If any DTCs are set Refer to: Diagnostic Trouble Code (DTC) List - Vehicle ⇓ If no DTCs are set
  3. Verify the appropriate scan tool Driver or Passenger Seat Switch parameters listed below change between Inactive and Forward/Rearward or Up/Down when pressing the appropriate switch. Seat Horizontal Switch Seat Cushion Front Vertical Switch Seat Cushion Rear Vertical Switch Seat Back Switch ⇒ If the parameter does not change Test or replace the S64 Front Seat Adjuster Switch ⇓ If the parameter changes
  4. Verify the appropriate scan tool Driver or Passenger Lumbar Support Horizontal Switch parameter changes between Inactive and Forward/Rearward when pressing the lumbar horizontal switch in the Forward and Rearward directions. ⇒ If the parameter does not change in either direction Refer to Circuit/System Testing – Seat Lumbar Switch Circuit Test. ⇓ If the parameter changes for both directions
  5. Verify the scan tool Lumbar Support Vertical Switch parameter changes between Inactive and Up/Down when pressing the lumbar vertical switch in the Up and Down directions. ⇒ If the parameter does not change Test or replace the S65 Front Seat Lumbar Switch. ⇓ If the parameter changes
  6. If equipped, Verify the scan tool Seat Back Side Bolster Switch parameter changes between Inactive and Inflate/Deflate when pressing the bolster switch in both directions. ⇒ If the parameter does not change Test or replace the S65 Front Seat Lumbar Switch. ⇓ If the parameter changes
  7. If equipped, Verify the scan tool Seat Cushion Side Bolster Switch parameter changes between Inactive and Inflate/Deflate when pressing the bolster switch in both directions. ⇒ If the parameter does not change Test or replace the S65 Front Seat Lumbar Switch. ⇓ If the parameter changes
  8. If equipped, Verify the scan tool Seat Massage Switch parameter changes between Inactive and On/Off when pressing the seat massage switch. ⇒ If the parameter does not change Test or replace the S65 Front Seat Lumbar Switch. ⇓ If the parameter changes
  9. Verify the lumbar/bolster/massage functions listed below operate while operating the lumbar switches in both directions. Lumbar Support Horizontal Lumbar Support Vertical Seat Back Side Bolster (If equipped) Seat Cushion Side Bolster (If equipped) Seat Massage (If equipped) ⇒ If any lumbar/bolster/massage function does not operate Refer to Circuit/System Testing – Seat Lumbar Circuit Test. ⇓ If all lumbar/bolster/massage functions operate
  10. A fault is currently not present and may be an intermittent condition. Circuit/System Testing Seat Lumbar Switch Circuit Test
  11. Ignition/Vehicle OFF, disconnect the connector at the appropriate front seat lumbar switch listed below. It may take up to 2 min for all vehicle systems to power down. S65D Front Seat Lumbar Switch – Driver S65P Front Seat Lumbar Switch – Passenger
  12. Test for less than 10 Ω between the low reference circuit terminal 4 and ground. ⇒ If 10 Ω or greater 2.1. Test the appropriate low reference circuit listed below for an open/high resistance: S65D Front Seat Lumbar Switch – Driver = Circuit 2817 S65P Front Seat Lumbar Switch – Passenger = Circuit 2815 ⇒ If an open/high resistance is found, repair the fault on the circuit. ⇓ If an open/high resistance is not found 2.2. Replace the appropriate S64 Front Seat Adjuster Switch. ⇓ If less than 10 Ω
  13. Ignition/Vehicle in Service Mode.
  14. Test for 4.8–5.2 V between the signal circuit terminal 3 and ground. ⇒ If less than 4.8 V 4.1. Test the appropriate circuit for a short to ground: S65D Front Seat Lumbar Switch – Driver = Circuit 2818 S65P Front Seat Lumbar Switch – Passenger = Circuit 2816 ⇒ If a short to ground is found, repair the fault on the circuit. ⇓ If a short to ground is not found 4.2. Test the appropriate circuit for an open/high resistance: S65D Front Seat Lumbar Switch – Driver = Circuit 2818 S65P Front Seat Lumbar Switch – Passenger = Circuit 2816 ⇒ If an open/high resistance is found, repair the fault on the circuit. ⇓ If an open/high resistance is not found 4.3. Replace the appropriate S64 Front Seat Adjuster Switch. ⇒ If greater than 5.2 V 4.1. Test the appropriate circuit for a short to voltage: S65D Front Seat Lumbar Switch – Driver = Circuit 2818 S65P Front Seat Lumbar Switch – Passenger = Circuit 2816 ⇒ If a short to voltage is found, repair the fault on the circuit. ⇓ If a short to voltage is not found 4.2. Replace the appropriate S64 Front Seat Adjuster Switch. ⇓ If between 4.8–5.2 V
  15. Ignition/Vehicle OFF, connect the connector at the S65 Front Seat Lumbar Switch and disconnect the connector at the appropriate S64 Front Seat Adjuster Switch.
  16. Connect a DMM between the signal circuit terminal 5 and the low reference circuit terminal 6.
  17. Test for the resistance values listed below while pressing the appropriate S65 Front Seat Lumbar Switch. 450–500 Ω for Switch 1 1012–1118 Ω for Switch 2 1854–2050 Ω for Switch 3 3280–3625 Ω for Switch 4 6072–6712 Ω for Switch 5 ⇒ If not between the specified values Test or replace the appropriate S65 Front Seat Lumbar Switch. ⇓ If between the specified values
  18. Test or replace the S64 Front Seat Adjuster Switch. Seat Lumbar Circuit Test
  19. Ignition/Vehicle OFF, disconnect the connector at the appropriate front seat bolster memory module listed below. It may take up to 2 min for all vehicle systems to power down. K104DP Front Seat Bladder Control Module - Driver Primary K104PP Front Seat Bladder Control Module - Passenger Primary
  20. Test for less than 10 Ω between the ground circuit terminal 4 and ground. ⇒ If 10 Ω or greater 2.1. Test the appropriate circuit for an open/high resistance: K104DP Front Seat Bladder Control Module - Driver Primary = Circuit 1150 K104PP Front Seat Bladder Control Module - Passenger Primary = Circuit 1250 ⇒ 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
  21. Ignition/Vehicle in Service Mode.
  22. Verify a test lamp illuminates between the B+ circuit terminal 1 and ground. ⇒ If the test lamp does not illuminate 4.1. Test the appropriate circuit for a short to ground: K104DP Front Seat Bladder Control Module - Driver Primary = Circuit 2240 K104PP Front Seat Bladder Control Module - Passenger Primary = Circuit 3940 ⇒ If a short to ground is found, repair the fault on the circuit. ⇓ If a short to ground is not found 4.2. Test the appropriate circuit for an open/high resistance: K104DP Front Seat Bladder Control Module - Driver Primary = Circuit 2240 K104PP Front Seat Bladder Control Module - Passenger Primary = Circuit 3940 ⇒ 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
  23. Ignition/Vehicle OFF, connect the connector at the K104 Front Seat Bladder Control Module and disconnect the connector at the appropriate front seat back lumbar pump listed below: G31D Front Seat Back Lumbar Pump – Driver G31P Front Seat Back Lumbar Pump – Passenger
  24. Connect a test lamp between the control circuit terminal 1 and ground circuit terminal 2.
  25. Ignition/Vehicle in Service Mode.
  26. Verify the test lamp turns ON when pressing the lumbar forward switch. ⇒ If the test lamp remains OFF 8.1. Test the appropriate circuits for a short to ground: G31D Front Seat Back Lumbar Pump – Driver = Circuit 2305 and circuit 4891 G31P Front Seat Back Lumbar Pump – Passenger = Circuit 2306 and circuit 4890 ⇒ If a short to ground is found, repair the fault on the circuit. ⇓ If a short to ground is not found 8.2. Test the appropriate circuits for an open/high resistance: G31D Front Seat Back Lumbar Pump – Driver = Circuit 2305 and circuit 4891 G31P Front Seat Back Lumbar Pump – Passenger = Circuit 2306 and circuit 4890 ⇒ 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 appropriate K104 Front Seat Bladder Control Module. ⇒ If the test lamp remains ON 8.1. Test the appropriate circuits for a short to voltage: G31D Front Seat Back Lumbar Pump – Driver = Circuit 2305 and circuit 4891 G31P Front Seat Back Lumbar Pump – Passenger = Circuit 2306 and circuit 4890 ⇒ 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 appropriate K104 Front Seat Bladder Control Module. ⇓ If the test lamp turns ON and OFF
  27. Test or replace the appropriate G31 Front Seat Back Lumbar Pump. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair.