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Tahoe / Yukon Service Manual

DTC B19C8 or B19C9

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 B19C8 Right Front Door Exterior Switch Unlock Signal DTC B19C9 Left Front Door Exterior Switch Unlock 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
2675 Signal B19C9 9E* 1 — —
2676 Signal B19C8 9E* 2 — —
1150 Ground — 1 — —
1251 Ground — 2 — —
* Service Door Latch System= Displayed 1. B27LF Front Side Door Outside Handle Switch - Left = Inoperative 2. B27RF Front Side Door Outside Handle Switch - Right = Inoperative

Circuit/System Description The K9 Body Control Module provides the B27LF Front Side Door Outside Handle Switch - Left with approximately 7.5V to the signal circuit 2675. Ground is applied at all times to the B27LF Front Side Door Outside Handle Switch - Left. When the switch is pressed, ground is applied to the K9  Body control Module through signal circuit 2675. The K9 Body Control Module will detect the voltage drop in the signal circuit 2675 and will command the doors to perform the LOCK/UNLOCK command. The K9 Body Control Module provides the B27RF Front Side Door Outside Handle Switch - Right with approximately 7.5V to the signal circuit 2676. Ground is applied at all times to the B27RF  Front Side Door Outside Handle Switch - Right. When the switch is pressed, ground is applied to the K9 Body control Module through signal circuit 2676. The K9 Body Control Module will detect the voltage drop in the signal circuit 2676 and will command the doors to perform the LOCK/UNLOCK command. Conditions for Running the DTC Ignition » On / Vehicle » In Service Mode Conditions for Setting the DTC B19C8 9E Circuit 2676= Stuck On — For greater than 60 s B19C9 9E Circuit 2675= Stuck On — For greater than 60 s Actions Taken When the DTC Sets B19C8 9E B27LF Front Side Door Outside Handle Switch - Left = Disabled B19C9 9E B27RF Front Side Door Outside Handle Switch - Right = 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. Diagnostic Aids A short to ground on any signal circuit 2675 or 2676 may cause the driver information center to display “Service Door Latch System”. The message will no longer display when the cause of the fault on the appropriate signal circuit has been removed. Reference Information Schematic Reference Door Lock/Indicator Schematics Connector End View Reference Master Electrical Component List Description and Operation Power Door Locks 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 Circuit/System Verification

  1. Ignition » On / Vehicle » In Service Mode
  2. Verify the scan tool parameter: Left Front Door Exterior Lock/Unlock Switch Status = Inactive ⇒ If not the specified state Refer to: Circuit/System Testing — Test 1 ⇓ If the specified state
  3. Operate the component: A24D Front Side Door Outside Handle - Left » Pressed Verify the scan tool parameter: Left Front Door Exterior Lock/Unlock Switch Status = Active ⇒ If not the specified state Refer to: Circuit/System Testing — Test 1 ⇓ If the specified state
  4. Verify the scan tool parameter: Right Front Door Exterior Lock/Unlock Switch Status = Inactive ⇒ If not the specified state Refer to: Circuit/System Testing — Test 2 ⇓ If the specified state
  5. Operate the component: A24P Front Side Door Outside Handle - Right » Pressed Verify the scan tool parameter: Right Front Door Exterior Lock/Unlock Switch Status = Active ⇒ If not the specified state Refer to: Circuit/System Testing — Test 2 ⇓ If the specified state
  6. A fault is not currently present and may be an intermittent condition Circuit/System Testing Test 1
  7. Ignition/vehicle OFF, disconnect the connector at the B27LF Front Side Door Outside Handle Switch - Left. Ignition ON
  8. Verify the scan tool Left Front Door Exterior Lock/Unlock Switch Status parameter is Inactive ⇒ If not Inactive 2.1. Test the circuit 2675 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. 2.2. Replace the K9 Body Control Module. ⇓ If Inactive
  9. Install a 3 A fused jumper wire between the signal circuit terminal 1 and ground.
  10. Verify the scan tool parameter is now Active. ⇒ If not Active and the 3 A fuse is OK 4.1. Test the circuit 2675 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. 4.2. Replace the K9 Body Control Module. ⇒ If not Active and the 3 A fuse is open 4.1. Test the circuit 2675 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. 4.2. Replace the K9 Body Control Module. ⇓ If Active
  11. Replace the B27LF Front Side Door Outside Handle Switch - Left Test 2
  12. Ignition/vehicle OFF, disconnect the connector at the B27RF Front Side Door Outside Handle Switch - Right. Ignition ON
  13. Verify the scan tool Right Front Door Exterior Lock/Unlock Switch Status parameter is Inactive ⇒ If not Inactive 2.1. Test the circuit 2676 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. 2.2. Replace the K9 Body Control Module. ⇓ If Inactive
  14. Install a 3 A fused jumper wire between the signal circuit terminal 1 and ground.
  15. Verify the scan tool parameter is now Active. ⇒ If not Active and the 3 A fuse is OK 4.1. Test the circuit 2676 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. 4.2. Replace the K9 Body Control Module. ⇒ If not Active and the 3 A fuse is open 4.1. Test the circuit 2676 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. 4.2. Replace the K9 Body Control Module. ⇓ If Active
  16. Replace the B27RF Front Side Door Outside Handle Switch - Right Component Testing
  17. Ignition/Vehicle » Off
  18. Disconnect the appropriate electrical connector: A24D Front Side Door Outside Handle - Left A24P Front Side Door Outside Handle - Right
  19. Test for infinite resistance between the test points: Signal terminal 1 & Ground terminal 5 » Not Pressed ⇒ If less than infinite resistance Replace the component: A24D Front Side Door Outside Handle - Left A24P Front Side Door Outside Handle - Right ⇓ If infinite resistance
  20. Test for less than 3 Ω between the test points: Signal terminal 1 & Ground terminal 5 » Pressed ⇒ If 3 Ω or greater Replace the component: A24D Front Side Door Outside Handle - Left A24P Front Side Door Outside Handle - Right ⇓ If less than 3 Ω
  21. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Front Side Door Outside Handle Replacement For control module replacement, programming, and setup refer to: Control Module References