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Tahoe / Yukon Service Manual

DTC B109D or B109E

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 B109D Passenger Seat Front Vertical Motor Up Control DTC B109E Passenger Seat Front Vertical Motor Down Control For symptom byte information refer to Symptom Byte List. Diagnostic Fault Information

Circuit Circuit Function Short to Ground Open/Hig Resistanc h Short to e Voltage Signal Performan
297 Control B109D 11 B109D 13 B109D 12 —
298 Control B109E 11 B109E 13 B109E 12 —

Circuit/System Description Battery voltage is supplied at all times to the seat memory control module through a 10 A fuse located in the instrument panel fuse block. This voltage is used by the module for logic power. Battery positive voltage is also supplied at all times to the seat memory control module through a 30 A fuse located in the instrument panel fuse block. This voltage is connected to a power rail internal to the seat memory control module and is used to drive the power seat actuators. Each seat motor is controlled by the seat memory control module by applying power and ground through the control circuits to the motor. All actuators are reversible. For example, when the seat switch is operated to move the entire seat forward, a serial data message is sent from the seat adjuster switch to the seat memory control module indicating the entire seat forward command. In response to this message, the seat memory control module applies battery voltage through the passenger seat horizontal motor forward control circuit and ground through the passenger seat horizontal motor rearward control circuit to the motor. The motor runs to drive the entire seat forward until the switch is released, the motor reaches the end of travel, or an obstruction prevents further seat movement. Moving the entire seat rearward works similarly to moving the entire seat forward, except that battery positive voltage and ground are applied on the opposite circuits causing the motor to run in the opposite direction. Conditions for Running the DTC Seat switch request or seat motor control must be active for greater than 3 s. Module battery voltage must be between 9–16 V. Conditions for Setting the DTC B109D 11 or B109E 11 The seat adjuster memory module detects a short to ground for greater than 100 ms. B109D 12 or B109E 12 The seat adjuster memory module detects a short to voltage for greater than 100 ms. B109D 13 or B109E 13 The seat adjuster memory module detects an open/high resistance in a control circuit for greater than 3 s. Action Taken When the DTC Sets The seat memory control module will not allow operation of any motor on the power rail for which the DTC was set. Conditions for Clearing the DTC The current DTC clears when the fault is no longer present and the seat switch request or seat motor control is active for greater than 3 s. The history DTC will clear after 40 consecutive fault-free Ignition/Vehicle ON/OFF switch cycles have occurred. Diagnostic Aids After servicing the memory seat system it is recommended to move the seat to a central, middle range position, then perform the memory store operation for memory “1”, “2”, and “Exit” or “3” if equipped. Refer to the Owner Manual for storing memory seat positions. Additionally, It is recommended to inform the vehicle owner that the stored memory positions may differ due to the servicing of the seat system. The K40P Passenger Seat Adjuster Memory Module must be awake when measuring voltage from either one of the memory seat switch signal circuits. If the module is not fully awake incorrect voltage readings are possible and may result in misdiagnosing the circuit. The K40P Passenger Seat Adjuster Memory Module must have seat positions stored to each position “1”, “2”, and “Exit” or “3” prior to that position recall functioning. Reference Information Schematic Reference Passenger Seat Schematics Connector End View Reference Master Electrical Component List Description and Operation Power Seats System Description and Operation Memory Seats 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 that DTC B109D and/or B109E are not set. ⇒ If a DTC is set Refer to Circuit/System Testing ⇓ If a DTC is not set
  3. Operate all power seat actuators in the Up/Down or Forward/Rearward directions.
  4. Verify that DTC B109D and/or B109E are not set. ⇒ If a DTC is set Refer to Circuit/System Testing ⇓ If a DTC is not set
  5. A fault is currently not present and may be an intermittent condition. Circuit/System Testing
  6. Ignition/Vehicle OFF, disconnect the X2 connector at the K40P Passenger Seat Adjuster Memory Module.
  7. Ignition/Vehicle in Service Mode.
  8. Test for less than 1 V between control circuit terminal 6 and ground. ⇒ If 1 V or greater 3.1. Test circuit 297 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 3.2. Test circuit 298 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 3.3. Replace the M50P Front Seat Tilt Adjuster Actuator - Passenger. ⇓ If less than 1 V
  9. Ignition/Vehicle OFF.
  10. Test for infinite resistance between control circuit terminal 6 and ground. ⇒ If less than infinite resistance 5.1. Test circuit 297 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 5.2. Test circuit 298 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 5.3. Replace the M50P Front Seat Tilt Adjuster Actuator - Passenger. ⇓ If infinite resistance
  11. Test for less than infinite resistance between control circuit terminal 6 and control circuit terminal 16. ⇒ If infinite resistance 6.1. Test circuit 297 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. Test circuit 298 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 6.3. Replace the M50P Front Seat Tilt Adjuster Actuator - Passenger. ⇓ If less than infinite resistance
  12. Replace the M50P Front Seat Tilt Adjuster Actuator - Passenger.
  13. Connect the X2 connector at the K40P Passenger Seat Adjuster Memory Module.
  14. Clear all DTCs.
  15. Operate all power seat actuators in the Up/Down or Forward/Rearward directions.
  16. Verify DTC B109D and/or B109E do not set. ⇒ If any DTC sets Replace the K40P Passenger Seat Adjuster Memory Module. ⇓ If no DTC sets
  17. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. Control Module References for K40P Passenger Seat Adjuster Memory Module replacement, programming and setup