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Tahoe / Yukon Service Manual

DTC B1954

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 B1954 Left Rear Window Switch Symptom Byte Information: Symptom Byte List Diagnostic Fault Information

Circuit Number Circuit Function Short to Ground Open/High Resistance Short to Voltage Signal Performan
1185 Signal B1954 11 1 1 —
1187 Signal B1954 11 1 1 —
5048 Signal B1954 11 1 1 —
1. M74LR Rear Side Door Window Regulator Motor-Left= Inoperative

Circuit/System Description The window motors supply 12V signal circuits to their respective window switches, when a window switch has been activated, a switch closes providing a ground to the appropriate signal circuit causing the voltage to drop to 0V. The window motor will detect the voltage drop in the signal circuit and will command the window to move in the desired direction. Conditions for Running the DTC Ignition/Vehicle = All power modes Voltage between 10–16 V Conditions for Setting the DTC B1954 11 1185= Short to Ground — For greater than 60 s 1187= Short to Ground — For greater than 60 s 5048= Short to Ground — For greater than 60 s B1954 49 S79LR Rear Side Door Window Switch-Left= Internal Malfunction B1954 96 S79LR Rear Side Door Window Switch-Left= Component Internal Malfunction Actions Taken When the DTC Sets S79LR Rear Side Door Window Switch-Left— The left rear window motor may be inoperative or may be inoperative in the up function, the down function or the express functions from the left rear window switch. Conditions for Clearing the DTC B1954 11 A current DTC will clear when the diagnostic runs and passes. A history DTC will clear after 40 consecutive malfunction-free ignition cycles. B1954 49, B1954 96 If set as a current DTC » Replace the component: S79LR Rear Side Door Window Switch-Left Reference Information Schematic Reference Moveable Window Schematics Connector End View Reference Master Electrical Component List Description and Operation Power Windows 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. Vehicle Power Mode » Run/Service Mode.
  2. Operate the component: S79LR Rear Side Door Window Switch-Left» Pressed & Pulled Verify the component works as specified: M74LR Rear Side Door Window Regulator Motor-Left= Up M74LR Rear Side Door Window Regulator Motor-Left = Express Up M74LR Rear Side Door Window Regulator Motor-Left= Down M74LR Rear Side Door Window Regulator Motor-Left= Express Down ⇒ If the component does not work as specified Refer to: Circuit/System Testing ⇓ If the component works as specified
  3. A fault that is not currently present may have been caused by a intermittent condition. Circuit/System Testing
  4. Vehicle Power Mode » Off.
  5. Disconnect the electrical connector: M74LR Rear Side Door Window Regulator Motor-Left.
  6. Connect a test lamp between the test points: Signal circuit terminal 3 & B+.
  7. Vehicle Power Mode » Run/Service Mode.
  8. Operate the component: S79LR Rear Side Door Window Switch-Left» Pulled. Verify the test lamp state: S79LR Rear Side Door Window Switch-Left» Not Used = Test lamp Off S79LR Rear Side Door Window Switch-Left» Pulled = Test lamp On ⇒ If the test lamp is always OFF 5.1. Vehicle Power Mode » Off. 5.2. Remove the test lamp, disconnect the harness connector at the S79LR Rear Side Door Window Switch - Left. 5.3. Test for less than 2 Ω in the circuit 1185 end to end. ⇒ If 2 Ω or greater, repair the open/high resistance in the circuit. ⇓ If less than 2 Ω. 5.4. Vehicle Power Mode » Run/Service Mode. 5.5. Test for less than 1 V between the circuit 1185 and ground. ⇒ If 1 V or greater, repair the short to voltage on the circuit. ⇒ If less than 1 V, replace the S79LR Rear Side Door Window Switch - Left. ⇒ If the test lamp is always ON 5.1. Vehicle Power Mode » Off. 5.2. Remove the test lamp, disconnect the harness connector at the S79LR Rear Side Door Window Switch - Left. 5.3. Test for infinite resistance between the circuit 1185 and ground. ⇒ If less than infinite resistance, repair the short to ground on the circuit. ⇒ If infinite resistance, replace the S79LR Rear Side Door Window Switch - Left. ⇓ If the test lamp turns ON and OFF
  9. Connect a test lamp between the test points: Signal circuit terminal 7 & B+.
  10. Vehicle Power Mode » Run/Service Mode.
  11. Operate the component: S79LR Rear Side Door Window Switch-Left» Pressed. Verify the test lamp state: S79LR Rear Side Door Window Switch-Left» Not Used = Test lamp Off S79LR Rear Side Door Window Switch-Left» Pressed = Test lamp On ⇒ If the test lamp is always OFF 8.1. Vehicle Power Mode » Off. 8.2. Remove the test lamp, disconnect the harness connector at the S79LR Rear Side Door Window Switch - Left. 8.3. Test for less than 2 Ω in the circuit 1187 end to end. ⇒ If 2 Ω or greater, repair the open/high resistance in the circuit. ⇓ If less than 2 Ω. 8.4. Vehicle Power Mode » Run/Service Mode. 8.5. Test for less than 1 V between the circuit 1187 and ground. ⇒ If 1 V or greater, repair the short to voltage on the circuit. ⇒ If less than 1 V, replace the S79LR Rear Side Door Window Switch - Left. ⇒ If the test lamp is always ON 8.1. Vehicle Power Mode » Off. 8.2. Remove the test lamp, disconnect the harness connector at the S79LR Rear Side Door Window Switch - Left. 8.3. Test for infinite resistance between the circuit 1187 and ground. ⇒ If less than infinite resistance, repair the short to ground on the circuit. ⇒ If infinite resistance, replace the S79LR Rear Side Door Window Switch - Left. ⇓ If the test lamp turns ON and OFF
  12. Connect a test lamp between the test points: Signal circuit terminal 5 & B+.
  13. Vehicle Power Mode » Run/Service Mode.
  14. Operate the component: S79LR Rear Side Door Window Switch-Left» Pressed & Pulled Verify the test lamp state: S79LR Rear Side Door Window Switch-Left» Not Used = Test lamp Off S79LR Rear Side Door Window Switch-Left» Pressed = Test lamp On S79LR Rear Side Door Window Switch-Left» Pulled = Test lamp On ⇒ If the test lamp is always OFF 11.1. Vehicle Power Mode » Off. 11.2. Remove the test lamp, disconnect the harness connector at the S79LR Rear Side Door Window Switch - Left. 11.3. Test for less than 2 Ω in the circuit 5048 end to end. ⇒ If 2 Ω or greater, repair the open/high resistance in the circuit. ⇓ If less than 2 Ω. 11.4. Vehicle Power Mode » Run/Service Mode. 11.5. Test for less than 1 V between the circuit 5048 and ground. ⇒ If 1 V or greater, repair the short to voltage on the circuit. ⇒ If less than 1 V, replace the S79LR Rear Side Door Window Switch - Left. ⇒ If the test lamp is always ON 11.1. Vehicle Power Mode » Off. 11.2. Remove the test lamp, disconnect the harness connector at the S79LR Rear Side Door Window Switch - Left. 11.3. Test for infinite resistance between the circuit 5048 and ground. ⇒ If less than infinite resistance, repair the short to ground on the circuit. ⇒ If infinite resistance, replace the S79LR Rear Side Door Window Switch - Left. ⇓ If the test lamp turns ON and OFF
  15. Test or replace the component: M74LR Rear Side Door Window Regulator Motor-Left. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Rear Side Door Window Switch Replacement Rear Side Door Window Regulator Motor Replacement