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Tahoe / Yukon Service Manual

Power Seat Malfunction (Driver Without AUN_A45)

Power Seat Malfunction (Driver Without 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
5040 B+ 1 1 — —
286 Control 1 2 — —
287 Control 1 2 — —
284 Control 1 3 — —
285 Control 1 3 — —
282 Control 1 4 — —
283 Control 1 4 — —
277 Control 1 5 — —
278 Control 1 5 — —
1150 Ground — 1 — —
1. All power seat actuators are inoperative 2. The front seat tilt adjuster actuator is inoperative 3. The front seat horizontal adjuster actuator is inoperative 4. The front seat vertical adjuster actuator is inoperative 5. The front seat recliner actuator is inoperative

Circuit/System Description Battery voltage is supplied at all times to the seat adjuster switch through a 30 A fuse located in the instrument panel fuse block. When the seat switches are in an inactive state, the switch contacts are closed to the switch ground circuit. All seat actuator are reversible. For example, when the seat horizontal forward switch is pressed to move the entire seat forward, battery voltage is applied through the switch contacts and the seat horizontal motor forward control circuit to the actuator. With the horizontal motor rearward switch contacts closed to the switch ground circuit, the actuator runs in order 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 voltage and ground are applied on opposite circuits causing the actuator to run in the opposite direction. All seat actuator are powered this way. Reference Information Schematic Reference Driver Seat Schematics Connector End View Reference Master Electrical Component List Description and Operation Power Seats System Description and Operation Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs Circuit/System Verification

  1. Verify the driver seat directional actuators listed below operate in both directions, from the S64D Front Seat Adjuster Switch - Driver. 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 all seat motors do not operate Refer to Circuit/System Testing – Seat Adjuster Switch Circuit Test. ⇒ If 1 or more seat motors operate but not all Refer to Circuit/System Testing – Seat Motor Circuit Test. ⇓ If all seat motors operate
  2. A fault is currently not present and may be an intermittent condition. Circuit/System Testing Seat Adjuster Switch Circuit Test
  3. Ignition/Vehicle OFF, disconnect the connector at the S64D Front Seat Lumbar Switch - Driver.
  4. Test for less than 10 Ω between the ground circuit terminal J 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
  5. Ignition/Vehicle in Service Mode.
  6. Verify a test lamp illuminates between the B+ circuit terminal A 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
  7. Test or replace the S64D Front Seat Lumbar Switch - Driver. Seat Motor Circuit Test
  8. Ignition/Vehicle OFF, disconnect the connector at the appropriate seat actuator 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
  9. Connect a test lamp between control circuit terminal 1 and control circuit terminal 3.
  10. Ignition/Vehicle in Service Mode.
  11. Verify the test lamp illuminates when commanding the seat motor Up/Down or Forward/Rearward using the S64D Front Seat Lumbar Switch - Driver. ⇒ If the test lamp does not illuminate during either of the commands 4.1. Test the appropriate circuits listed below for a short to ground: M50D Front Seat Tilt Adjuster Actuator - Driver = Circuit 287 and circuit 288 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 4.2. Test the appropriate circuits listed below for an open/high resistance: M50D Front Seat Tilt Adjuster Actuator - Driver = Circuit 287 and circuit 288 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 4.3. Replace the S64D Front Seat Lumbar Switch - Driver. ⇓ If the test lamp illuminates during each of the commands
  12. Test or replace the appropriate seat actuator 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 Adjuster Switch Test
  13. Ignition/Vehicle OFF, disconnect the connector at the S64 Front Seat Adjuster Switch.
  14. Test for infinite resistance between the B+ terminal and each control terminal with the switch in the open position. ⇒ If less than infinite resistance Replace the S64 Front Seat Adjuster Switch. ⇓ If infinite resistance
  15. Test for less than 2 Ω between the B+ terminal and each control terminal with the appropriate switch in the closed position. ⇒ If 2 Ω or greater Replace the S64 Front Seat Adjuster Switch. ⇓ If less than 2 Ω
  16. Test for less than 2 Ω between the ground terminal and each control terminal with the switch in the open position. ⇒ If 2 Ω or greater Replace the S64 Front Seat Adjuster Switch. ⇓ If less than 2 Ω
  17. All OK. Seat Motor
  18. Ignition/Vehicle OFF, disconnect the connector at the appropriate seat actuator listed below: M50 Front Seat Tilt Adjuster Actuator M51 Front Seat Adjuster Actuator M55 Front Seat Vertical Adjuster Actuator M56 Front Seat Recliner Actuator
  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 actuator should momentarily perform the appropriate FORWARD/ REARWARD/ UP/ DOWN function. ⇒ If the actuator does not perform the FORWARD/ REARWARD/ UP/ DOWN function Replace the actuator. ⇓ If the actuator performs the FORWARD/ REARWARD/ UP/ DOWN function
  3. Reverse the jumper wires; the actuator should perform FORWARD/ REARWARD/ UP/ DOWN function. ⇒ If the actuator does not perform the FORWARD/ REARWARD/ UP/ DOWN function Replace the actuator. ⇓ If the actuator 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 Front Seat Tilt Adjuster Actuator Replacement Front Seat Cushion Frame Replacement Front Seat Recliner Actuator Replacement