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Tahoe / Yukon Service Manual

DTC B16C5 (TB4)

Diagnostic Instructions Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis An overview of each diagnostic category can be found here: Diagnostic Procedure Instructions DTC Descriptor DTC B16C5 Rear Closure Handle Switch Open Signal Symptom Byte Information: Symptom Byte List Diagnostic Fault Information

Circuit number Circuit Function Short to Ground Open/High Resistance Short to Voltage Signal Performan
5797 Signal B16C5 32 1 1 —
2050 Ground — 1 — —
1. S45A Liftgate Release Switch - Exterior= Inoperative

Circuit/System Description The K9 Body Control Module provides the S45A Liftgate Release Switch - Exterior with approximately 7.5V to the signal circuit 5797. When the switch is pressed, the K9 Body Control Module will detect the voltage drop in the signal circuit 5797, it will verify the doors have been commanded to unlock and will command the A23C Liftgate Latch to activate. If the doors are locked, the body control module will ignore the function of the S45A Liftgate Release Switch- Exterior. Conditions for Running the DTC Ignition » On / Vehicle » In Service Mode Conditions for Setting the DTC Circuit 5797= Signal Low Time < Minimum — For greater than 60 s Actions Taken When the DTC Sets S45A Liftgate Release Switch - Exterior= Disabled Conditions for Clearing the DTC A current DTC will clear when the diagnostic runs and passes. A history DTC will clear after 40 consecutive malfunction-free ignition cycles. Reference Information e e e ce o at o Schematic Reference Release Systems Schematics Connector End View Reference Master Electrical Component List Description and Operation Rear Hatch/Gate Description and Operation Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs Electrical Relay Replacement Scan Tool Reference Control Module References Circuit/System Verification

  1. Ignition » On / Vehicle » In Service Mode
  2. Operate the component: S13D Door Lock Switch - Driver » Unlock Switch
  3. Operate the component: S45A Liftgate Control Switch - Exterior » Pressed Verify the A23C Liftgate Latch will activate and allow the liftgate to be pulled open. ⇒ If the component does not activate Refer to: Circuit/System Testing ⇓ If all functions work properly
  4. A fault is not currently present and may be an intermittent condition Circuit/System Testing
  5. Ignition/vehicle OFF, disconnect the connector at the S45A Liftgate Release Switch - Exterior
  6. Verify a test lamp illuminates between ground circuit terminal 2 and B+. ⇒ If the test lamp does not illuminate 2.1. Repair the open/high resistance on circuit 2050 or the ground connection. ⇓ If the test lamp illuminates
  7. Ignition/vehicle On.
  8. Verify the A23C Liftgate Latch is not Active ⇒ If Active 4.1. Test the circuit 5797 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. Replace the K9 Body Control Module. ⇓ If Inactive
  9. Manually move the A23C Liftgate Latch to the Latched position
  10. Momentarily install a 3 A fused jumper wire between the signal circuit terminal 1 and ground. Verify the A23C Liftgate Latch performs the Unlatch function ⇒ If the A23C Liftgate Latch does not perform the Unlatch function and the 3 A fuse is OK 6.1. Test the circuit 5797 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. Replace the K9 Body Control Module. ⇒ If the A23C Liftgate Latch does not perform the Unlatch function and the 3 A fuse is open 6.1. Test the circuit 5797 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. 6.2. Replace the K9 Body Control Module. ⇓ If the A23C Liftgate Latch does Unlatch
  11. Replace the S45A Liftgate Release Switch - Exterior Component Testing
  12. Ignition/Vehicle » Off
  13. Disconnect the electrical connector: S45A Liftgate Release Switch - Exterior
  14. Test for infinite resistance between the test points: Signal terminal 1 & Ground terminal 2 — Switch » Not Pressed ⇒ If less than infinite resistance Replace the component: S45A Liftgate Release Switch - Exterior ⇓ If infinite resistance
  15. Test for less than 3 Ω between the test points: Signal terminal 1 & Ground terminal 2 — Switch » Pressed ⇒ If 3 Ω or greater Replace the component: S45A Liftgate Release Switch - Exterior ⇓ If less than 3 Ω
  16. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Liftgate Exterior Release Switch Replacement For control module replacement, programming, and setup refer to: Control Module References