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Tahoe / Yukon Service Manual

Power Mirror Folding Malfunction

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 Performance
2785 Control 1 1 — —
2786 Control 1 1 — —
2793 Control 1 1 — —
2794 Control 1 1 — —
1. Power Folding Mirror Inoperative

Circuit/System Description The outside mirror switch, which is part of the S79D Driver Front Side Door Window Control Switch is used with the S79P Passenger Front Side Door Window Control Switch to activate the fold/unfold motors through bi-directional control circuits. Voltage is sent to the commanded mirror via a mirror control circuit. The opposite mirror control circuit acts as a ground circuit for the bi- directional mirror motor. Ground is applied through the switch, The outside rearview mirror switch will also send a serial data message to the K9 Body Control Module requesting the mirror fold/unfold command, the S79D Driver Front Side Door Window Control Switch will then send the command to the S79P Passenger Front Side Door Window Control Switch which will also command the passenger mirror to fold or unfold. Reference Information Schematic Reference Outside Rearview Mirror Schematics Connector End View Reference Master Electrical Component List Description and Operation Outside Mirror Description and Operation Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs Circuit/System Verification

  1. Ignition ON.
  2. Verify the A9A Outside Rearview Mirror-Driver FOLD and UNFOLD when commanding the Driver Mirror Fold Motor to Fold and Unfold with a scan tool. ⇒ If the A9A Outside Rearview Mirror-Driver does not FOLD and UNFOLD Refer to Circuit/System Testing – Driver Outside Mirror Folding Command Malfunction. ⇓ If the A9A Outside Rearview Mirror-Driver does FOLD and UNFOLD
  3. Verify the A9B Outside Rearview Mirror-Passenger FOLD and UNFOLD when commanding the Passenger Mirror Fold Motor to Fold and Unfold with a scan tool. ⇒ If the A9B Outside Rearview Mirror-Passenger does not FOLD and UNFOLD Refer to Circuit/System Testing – Passenger Outside Mirror Folding Command Malfunction. ⇓ If the A9B Outside Rearview Mirror-Passenger does FOLD and UNFOLD
  4. A fault is not currently present and may be an intermittent condition. Circuit/System Testing Driver Outside Mirror Folding Command Malfunction
  5. Ignition OFF and all vehicle systems OFF, disconnect the X510 inline connector at the A9A Outside Rearview Mirror — Driver. It may take up to 2 minutes for all vehicle systems to power down.
  6. Verify a test lamp illuminates between the control circuit terminal 15 and B+. ⇒ If the test lamp does not illuminate 2.1. Test circuit 2785 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. Replace the S79D Front Side Door Window Control Switch — Driver. ⇓ If the test lamp illuminates
  7. Verify a test lamp illuminates between the control circuit terminal 3 and B+. ⇒ If the test lamp does not illuminate 3.1. Test circuit 2786 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. 3.2. Replace the S79D Front Side Door Window Control Switch — Driver. ⇓ If the test lamp illuminates
  8. Connect a test lamp between control circuit terminal 15 and control circuit terminal 3, ignition ON.
  9. Verify the test lamp turns ON when commanding the FOLD and UNFOLD with the S79D Front Side Door Window Control Switch — Driver. ⇒ If the test lamp remains OFF during either of the commands 5.1. Test the following circuits for a short to ground: Circuit 2785 Circuit 2786 ⇒ 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 S79D Front Side Door Window Control Switch — Driver. ⇓ If the test lamp turns ON during each of the commands
  10. Test or replace the A9A Outside Rearview Mirror-Driver. Passenger Outside Mirror Folding Command Malfunction
  11. Ignition OFF and all vehicle systems OFF, disconnect the X510 inline connector at the A9B Outside Rearview Mirror — Passenger. It may take up to 2 minutes for all vehicle systems to power down.
  12. Verify a test lamp illuminates between the control circuit terminal 15 and B+. ⇒ If the test lamp does not illuminate 2.1. Test circuit 2793 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. Replace the S79P Front Side Door Window Switch — Passenger. ⇓ If the test lamp illuminates
  13. Verify a test lamp illuminates between the control circuit terminal 3 and B+. ⇒ If the test lamp does not illuminate 3.1. Test circuit 2794 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. 3.2. Replace the S79P Front Side Door Window Switch — Passenger. ⇓ If the test lamp illuminates
  14. Connect a test lamp between control circuit terminal 15 and control circuit terminal 3, ignition ON.
  15. Verify the test lamp turns ON when commanding the FOLD and UNFOLD with the S79D Front Side Door Window Control Switch — Driver. ⇒ If the test lamp remains OFF during either of the commands 5.1. Test the following circuits for a short to ground: Circuit 2793 Circuit 2794 ⇒ 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 S79P Front Side Door Window Switch — Passenger. ⇓ If the test lamp turns ON during each of the commands
  16. Test or replace the A9A Outside Rearview Mirror-Driver. Component Testing Outside Rearview Mirror
  17. Ignition OFF, disconnect the inline connector at the appropriate A9 Outside Rearview Mirror.
  18. Install a 10 A fused jumper wire between one of the control terminals and 12 V. Momentarily install a jumper wire between the other control terminal and ground. Reverse the jumper wires at least two times, the A9 Outside Rearview Mirror should perform the FOLD and ⇒ If the function does not perform the FOLD and UNFOLD functions Replace the A9 Outside Rearview Mirror. ⇓ If the function performs the FOLD and UNFOLD functions
  19. A fault is not currently present and may be an intermittent condition. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. Front Side Door Window Control Switch Replacement