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Tahoe / Yukon Service Manual

Power Seat Malfunction (Driver With AUN_A45)

Power Seat Malfunction (Driver With AUN/A45) 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
2240 B+ — U0211 — —
5040 B+ — 1 — —
3758 Serial Data — U0260 — —
287 Control B1095 11 B1095 13 B1095 12 —
286 Control B1094 11 B1094 13 B1094 12 —
285 Control B1093 11 B1093 13 B1093 12 —
284 Control B1092 11 B1092 13 B1092 12 —
283 Control B1091 11 B1091 13 B1091 12 —
282 Control B1090 11 B1090 13 B1090 12 —
277 Control B1A85 11 B1A85 13 B1A85 12 —
276 Control B1A84 11 B1A84 13 B1A84 12 —
1150 Ground — U0211 — —
1. All power seat and memory functions are inoperative

Scan Tool Data K40D Driver Seat Adjuster Memory Module Normal Operation Data List Parameter Values

Data List Parameter Values Normal Operation
Seat Position Data Seat Cushion Front Vertical Switch Inactive/Upward/D This parameter indicates the ownward state of the seat position switch.
Seat Cushion Rear Vertical Switch Inactive/Upward/D This parameter indicates the ownward state of the seat position switch.
Seat Horizontal Switch Inactive/Forward/ This parameter indicates the Rearward state of the seat position switch.
Seat Back Switch Inactive/Forward/ This parameter indicates the Rearward state of the seat position switch.

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 motors. Each seat motor is controlled by the seat memory control module by applying power and ground through the control circuits to the motor. All motors 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 driver seat horizontal motor forward control circuit and ground through the driver seat horizontal motor rearward control circuit to the motor. The motor runs to drive the entire seat forward until the switch is released. 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. 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 K40D Driver 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 K40D Driver 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 Driver 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 no DTCs are set. ⇒ If any DTC is set Refer to Diagnostic Trouble Code (DTC) List - Vehicle. ⇓ If no DTCs are set
  3. Verify the appropriate driver scan tool seat switch parameters listed below change between Inactive and Forward/Rearward or Up/Down when pressing the switch. Seat Horizontal Switch Seat Cushion Front Vertical Switch Seat Cushion Rear Vertical Switch Seat Back Switch ⇒ If the parameter does not change Replace the S64D Front Seat Adjuster Switch - Driver. ⇓ If the parameter changes
  4. Verify the seat directional motors listed below operate while operating the appropriate seat switches in both directions. M50D Front Seat Tilt Adjuster Actuator - Driver M51D Front Seat Adjuster Actuator - Driver M55D Front Seat Vertical Adjuster Actuator - Driver M56D Front Seat Recliner Actuator - Driver ⇒ If any seat motor does not operate Refer to Circuit/System Testing. ⇓ If all seat motors operate
  5. A fault is currently not present and may be an intermittent condition. Circuit/System Testing
  6. Ignition/Vehicle OFF, disconnect the X1 connector at the K40D Driver Seat Adjuster Memory Module.
  7. Test for less than 10 Ω between ground circuit terminal 1 and ground. ⇒ If 10 Ω or greater 2.1. Test circuit 1150 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
  8. Ignition/Vehicle in Service Mode.
  9. Verify that a test lamp illuminates between the B+ circuit terminal 6 and ground. ⇒ If the test lamp does not illuminate. 4.1. Test circuit 5040 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 5040 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.
  10. Ignition/Vehicle OFF, connect the X1 connector at the K40D Driver Seat Adjuster Memory Module and disconnect the connector at the appropriate seat motor(s) listed below: M50D Front Seat Tilt Adjuster Actuator - Driver M51D Front Seat Adjuster Actuator - Driver M55D Front Seat Vertical Adjuster Actuator - Driver M56D Front Seat Recliner Actuator - Driver
  11. Connect a test lamp between control circuit terminal 1 and control circuit terminal 3.
  12. Ignition/Vehicle in Service Mode.
  13. Verify the test lamp turns ON while operating the appropriate seat switch in the Up/Down or Forward/Rearward directions. ⇒ If the test lamp remains OFF during either of the commands 8.1. Test the appropriate circuits listed below for a short to ground: M50D Front Seat Tilt Adjuster Actuator - Driver = Circuit 286 and circuit 287 M51D Front Seat Adjuster Actuator - Driver = Circuit 284 and circuit 285 M55D Front Seat Vertical Adjuster Actuator - Driver = Circuit 282 and circuit 283 M56D Front Seat Recliner Actuator - Driver = Circuit 276 and circuit 277 ⇒ 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 listed below for an open/high resistance: M50D Front Seat Tilt Adjuster Actuator - Driver = Circuit 286 and circuit 287 M51D Front Seat Adjuster Actuator - Driver = Circuit 284 and circuit 285 M55D Front Seat Vertical Adjuster Actuator - Driver = Circuit 282 and circuit 283 M56D Front Seat Recliner Actuator - Driver = Circuit 276 and circuit 277 ⇒ 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 K40D Driver Seat Adjuster Memory Module. ⇓ If the test lamp turns ON during each of the commands
  14. Test or replace the appropriate seat motor listed below: M50D Front Seat Tilt Adjuster Actuator - Driver M51D Front Seat Adjuster Actuator - Driver M55D Front Seat Vertical Adjuster Actuator - Driver M56D Front Seat Recliner Actuator - Driver Component Testing Seat Motor
  15. Ignition/Vehicle OFF, disconnect the connector at the appropriate seat motor listed below: M50D Front Seat Tilt Adjuster Actuator - Driver M51D Front Seat Adjuster Actuator - Driver M55D Front Seat Vertical Adjuster Actuator - Driver M56D Front Seat Recliner Actuator - Driver
  1. Install a 30 A fused jumper wire between control terminal 1 and 12 V.
  2. Momentarily install a jumper wire between control terminal 3 and ground. The seat motor should momentarily perform the appropriate FORWARD / REARWARD / UP / DOWN function. ⇒ If the motor does not perform the FORWARD / REARWARD / UP / DOWN function Replace the seat motor. ⇓ If the motor performs the FORWARD / REARWARD / UP / DOWN function
  3. Reverse the jumper wires; the motor should perform FORWARD / REARWARD / UP / DOWN function. ⇒ If the motor does not perform the FORWARD / REARWARD / UP / DOWN function Replace the seat motor. ⇓ If the motor performs the FORWARD / REARWARD / UP DOWN function
  4. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. Front Seat Adjuster Switch Replacement Control Module References for K40D Driver Seat Adjuster Memory Module replacement, programming and setup