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Tahoe / Yukon Service Manual

DTC B1584, B1ABB, or B1ABC - Liftgate Latch Switches Malfunction

DTC B1584, B1ABB, or B1ABC - Liftgate Latch Switches 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. DTC Descriptor DTC B1584 Rear Closure Latch Unlatch Status DTC B1ABB Rear Closure Latch Neutral Status DTC B1ABC Rear Closure Latch Primary Status Symptom Byte Information: Symptom Byte List Diagnostic Fault Information

Circuit number Circuit Function Short to Ground Open/High Resistance Short to Voltage Signal Performan
4678 Signal — 1 — B1584 29
8085 Signal 1, 2, 3 B1584 29 — B1ABC 29
8084 Signal B1ABB 29 — — B1ABB 29
4656 Low Reference — 1 — —
1. Power liftgate functions disabled 2. Rear Access Open message always displayed 3. Liftgate latch may not perform the cinch function while latching

Circuit/System Description The K194 Rear Gate Module provides the A23C Liftgate Latch with approximately 12V to the signal circuit 4678, signal circuit 8085, and signal circuit 8084. Ground is provided by the K194 Rear Gate Module through low reference circuit 4656. The unlatch, primary, and neutral switches are part of the liftgate latch and are used by the rear gate module to determine the state of the latch during the process of cinching or unlatching. The unlatch and primary switches will be inactive when the primary and secondary latches are latched, and the neutral switch will be active during the power cinch function. Each of the latch switch signal circuits are supplied signal through a resistor and monitored within the rear gate module. The latch switches share a common low reference circuit from the rear gate module and when the switch contacts close the signal circuit goes low and the rear gate module determines the switch to be active. Conditions for Running the DTC The system voltage is 9–16 V. Conditions for Setting the DTC B1584 29, B1ABC 29 and B1ABB 29 When the rear gate module detects an open/high resistance in the 4678 signal circuit, 8085 signal circuit, and/or the 8084 signal circuit, or any incorrect combination of signals from the following switch inputs: Primary switch Unlatch switch Neutral switch Action Taken When the DTC Sets The liftgate may function in the manual mode only Liftgate latch may not perform the cinch function while latching The driver information center may continuously display Rear Access Open message Conditions for Clearing the DTC The DTC will be current for as long as the fault is present. When the fault is no longer present, the DTC will be a history DTC. A history DTC will clear after 40 ignition cycles. Diagnostic Aids If the liftgate will not release from the closed position, refer to Opening the Liftgate Without Electrical Power for the appropriate procedure Whenever the rear gate module loses power or is disconnected, the ignition must be cycled OFF then ON in order to reactivate the rear gate module. Reference Information Schematic Reference Liftgate Schematics Connector End View Reference Master Electrical Component List Description and Operation Liftgate 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 ON.
  2. Operate the component: Open the liftgate. Verify the scan tool parameter: Rear Gate Latch Unlatch Switch Signal = Active Rear Gate Latch Primary Switch Signal = Active Rear Gate Latch Neutral Switch Signal = Inactive
  3. Operate the component: Close the liftgate. & A23C Liftgate Latch » Latching Verify the scan tool parameter: Rear Gate Latch Unlatch Switch Signal = Active » Inactive Rear Gate Latch Primary Switch Signal = Active » Inactive Rear Gate Latch Neutral Switch Signal = Inactive » Active » Inactive ⇒ If the parameter value does not change Refer to: Circuit/System Testing ⇓ If the parameter value changes
  4. A fault is not currently present and may be an intermittent condition Circuit/System Testing
  5. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the A23C Liftgate Latch.
  6. Verify a test lamp turns On between the test points: Low Reference terminal 5 & B+ ⇒ If the test lamp does not turn On 2.1. Test circuit 4656 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 K194 Rear Gate Module. ⇓ If the test lamp turns On
  7. Ignition ON.
  8. Verify the scan tool Rear Gate Latch Unlatch Switch Signal parameter is Inactive. ⇒ If not Inactive 4.1. Test the circuit 4678 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 K194 Rear Gate Module. ⇓ If Inactive
  9. Install a 3 A fused jumper wire between the signal circuit terminal 6 and the low reference circuit terminal 5.
  10. Verify the scan tool Rear Gate Latch Unlatch Switch Signal parameter is Active ⇒ If not Active and the 3 A fuse is OK 6.1. Test the circuit 4678 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 K194 Rear Gate Module. ⇒ If not Active and the 3 A fuse is open 6.1. Test the circuit 4678 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 K194 Rear Gate Module. ⇓ If Active
  11. Verify the scan tool Rear Gate Latch Primary Switch Signal parameter is Inactive. ⇒ If not Inactive 7.1. Test the circuit 8085 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. 7.2. Replace the K194 Rear Gate Module. ⇓ If Inactive
  12. Install a 3 A fused jumper wire between the signal circuit terminal 7 and the low reference circuit terminal 5.
  13. Verify the scan tool Rear Gate Latch Primary Switch Signal parameter is Active ⇒ If not Active and the 3 A fuse is OK 9.1. Test the circuit 8085 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. 9.2. Replace the K194 Rear Gate Module. ⇒ If not Active and the 3 A fuse is open 9.1. Test the circuit 8085 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. 9.2. Replace the K194 Rear Gate Module. ⇓ If Active
  14. Verify the scan tool Rear Gate Latch Neutral Switch Signal parameter is Inactive. ⇒ If not Inactive 10.1. Test the circuit 8084 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. 10.2. Replace the K194 Rear Gate Module. ⇓ If Inactive
  15. Install a 3 A fused jumper wire between the signal circuit terminal 8 and the low reference circuit terminal 5.
  16. Verify the scan tool Rear Gate Latch Neutral Switch Signal parameter is Active ⇒ If not Active and the 3 A fuse is OK 12.1. Test the circuit 8084 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. 12.2. Replace the K194 Rear Gate Module. ⇒ If not Active and the 3 A fuse is open 12.1. Test the circuit 8084 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. 12.2. Replace the K194 Rear Gate Module. ⇓ If Active
  17. Test or replace the A23C Liftgate Latch. Repair Instructions Perform the Diagnostic Repair Verification after completing the diagnostic repair. Liftgate Latch Replacement Control Module References for the rear gate module replacement, setup and programming