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Tahoe / Yukon Service Manual

DTC B170C or B170E

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 B170C Driver Seat Blower Motor Control DTC B170E Passenger Seat Blower Motor Control Symptom Byte Information: Symptom Byte List Diagnostic Fault Information

Circuit Number Circuit Function Short to Ground Open/High Resistance Short to Voltage Signal Performan
139 B+ 1, 4 1, 2, 3, 4, 5, 6 — —
5906 Control B170C 1 B170C 1, 2, 3 B170C 1 —
5908 Control B170E 4 B170E 4, 5, 6 B170E 4 —
1150 Ground — 1, 2, 3 — —
1250 Ground — 4, 5, 6 — —
1. Driver Seat back and cushion ventilation functions are inoperative 2. Driver Seat back ventilation function is inoperative 3. Driver Seat cushion ventilation function is inoperative 4. Passenger Seat back and cushion ventilation functions are inoperative 2. Passenger Seat back ventilation function is inoperative 3. Passenger Seat cushion ventilation function is inoperative

Circuit/System Description The driver and front passenger vented seats are controlled by separate vented seat switches that are located in the A26 Heater and Air Conditioning User Interface Control - Front. When a vented seat switch is pressed, a LIN Bus serial message is sent from the A26 Heater and Air Conditioning User Interface Control - Front to the K9 Body Control Module. The K9 Body Control Module serves as the heated/vented seat system master to determine the requested operating mode. The K9  Body Control Module then sends a LIN bus serial data message to the K29FV Front Seat Heater Vent Control Module indicating the vented seat command. In response to this message, the K29FV Front Seat Heater Vent Control Module applies a low side drive pulse width modulation (PWM) signal through the blower motor control circuit to the seat back and cushion blower motors indicating the seat ventilation command. The logic in the blower motors sets the blower speed to the switch set point. The K9 Body Control Module then sends a serial data message back to the A26 Heater and Air Conditioning User Interface Control - Front to either illuminate or turn off the appropriate temperature indicator. Conditions for Running the DTC Ignition ON Conditions for Setting the DTC B170C The control module detects a fault on circuit 5906. B170E The control module detects a fault on circuit 5908. Action Taken When the DTC Sets The seat heater control module will disable all vented seat functions. Conditions for Clearing the DTC The DTC clears when the diagnostic runs and passes. The history DTC will clear after 40 consecutive fault-free ignition cycles have occurred. Reference Information Schematic Reference Heated/Cooled Seat Schematics Connector End View Reference Master Electrical Component List Description and Operation Heated/Vented Seat 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 that no other DTCs are set for the heated/vented seat system, besides DTCs B170C and B170E. ⇒ If any other DTCs are set for the heated/vented seat system Refer to: Diagnostic Trouble Code (DTC) List - Vehicle ⇓ If no other DTCs are set
  3. Verify DTCs B170C and B170E are not set. ⇒ If DTC B170C or B170E is set Refer to: Circuit/System Testing ⇓ If no DTC is set
  4. A fault is currently not present and may be an intermittent condition. Circuit/System Testing
  5. Ignition OFF and all vehicle systems OFF, disconnect the connector at the appropriate two seat blower motors listed below: DTC B170C = M73A Seat Blower Motor - Driver Back and M73C Seat Blower Motor - Driver Cushion DTC B170E = M73B Seat Blower Motor - Passenger Back and M73D Seat Blower Motor - Passenger Cushion
  6. Verify a test lamp illuminates between the appropriate ground circuit terminals listed below and B+, one at a time. DTC B170C = Terminal 3 at M73A Seat Blower Motor - Driver Back DTC B170C = Terminal 3 at M73D Seat Blower Motor - Driver Cushion DTC B170E = Terminal 3 at M73B Seat Blower Motor - Passenger Back DTC B170E = Terminal 3 at M73C Seat Blower Motor - Passenger Cushion ⇒ If the test lamp does not illuminate 2.1. Test the appropriate circuit for an open/high resistance: Terminal 3 at M73A Seat Blower Motor - Driver Back = Circuit 1150 Terminal 3 at M73D Seat Blower Motor - Driver Cushion = Circuit 1150 Terminal 3 at M73B Seat Blower Motor - Passenger Back = Circuit 1250 Terminal 3 at M73C Seat Blower Motor - Passenger Cushion = Circuit 1250 ⇓ If the test lamp illuminates
  7. Verify a test lamp illuminates between the appropriate B+ circuit terminals listed below and ground, one at a time. DTC B170C = Terminal 1 at M73A Seat Blower Motor - Driver Back DTC B170C = Terminal 1 at M73D Seat Blower Motor - Driver Cushion DTC B170E = Terminal 1 at M73B Seat Blower Motor - Passenger Back DTC B170E = Terminal 1 at M73C Seat Blower Motor - Passenger Cushion ⇒ If the test lamp does not illuminate and the circuit fuse is good Repair the open/high resistance on the circuit 139. ⇒ If the test lamp does not illuminate and the circuit fuse is open 3.1. Test the circuit 139 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 3.2. Replace the appropriate M73 Seat Blower Motor. ⇓ If the test lamp illuminates
  8. Connect a test lamp between the two appropriate control circuit terminal and B+, one at a time. DTC B170C = Terminal 2 at M73A Seat Blower Motor - Driver Back DTC B170C = Terminal 2 at M73D Seat Blower Motor - Driver Cushion DTC B170E = Terminal 2 at M73B Seat Blower Motor - Passenger Back DTC B170E = Terminal 2 at M73C Seat Blower Motor - Passenger Cushion
  9. Ignition ON, Verify the test lamp turns ON when pressing the vented seat switch through the High, Medium, and Low positions and the test lamp turns OFF when the OFF position is reached. ⇒ If the test lamp does not turn ON 5.1. Test the appropriate circuit for a short to voltage: DTC B170C = Circuit 5906 DTC B170E = Circuit 5908 ⇒ If a short to voltage is found, repair the fault on the circuit. ⇓ If a short to voltage is not found 5.2. Test the appropriate circuit for an open/high resistance: DTC B170C = Circuit 5906 DTC B170E = Circuit 5908 ⇒ If an open/high resistance is found, repair the fault on the circuit. ⇓ If an open/high resistance is not found 5.3. Replace the K29FV Front Seat Heater Vent Control Module. ⇒ If the test lamp does not turn OFF 5.1. Test the appropriate circuit for a short to ground: DTC B170C = Circuit 5906 DTC B170E = Circuit 5908 ⇒ If a short to ground is found, repair the fault on the circuit. ⇓ If a short to ground is not found 5.2. Replace the K29FV Front Seat Heater Vent Control Module. ⇓ If the test lamp turns ON and OFF
  10. Ignition OFF, connect the appropriate component listed below: DTC B170C = M73D Seat Blower Motor - Driver Cushion DTC B170E = M73C Seat Blower Motor - Passenger Cushion
  11. Clear the DTC.
  12. Ignition ON, operate the appropriate vented seat switch through the High, Medium, and Low positions and verify a DTC does not set. DTC B170C = Driver Vented Seat DTC B170E = Passenger Vented Seat ⇒ If a DTC sets 8.1. Replace the appropriate component listed below: DTC B170C = M73D Seat Blower Motor - Driver Cushion DTC B170E = M73C Seat Blower Motor - Passenger Cushion ⇓ If no DTC sets
  13. Replace the appropriate component listed below: DTC B170C = M73A Seat Blower Motor - Driver Back DTC B170E = M73B Seat Blower Motor - Passenger Back Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. Front Seat Back Ventilation Blower Replacement Front Seat Cushion Ventilation Blower Replacement Control Module References for K29FV Front Seat Heater Vent Control Module replacement, programming and setup