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Tahoe / Yukon Service Manual

Stop Lamps 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 Circuit Function Short to Ground Open/High Resistance Short to Voltage Signal Performan
5359 Voltage Reference C10DA 84 C10DA 84 1 —
5361 Signal C10DA 84 C10DA 84 C10DA 85, U0422 00 C10DA 27, C10DA 84, C10DA 85
5360 Low Reference 1 C10DA 85, U0422 00 1 —
7542 Control B198F 11 2 B198F 12 —
7541 Control B1990 11 2 B1990 12 —
820 Control 3 3 3 —
1950 Ground — 2 — —
2050 Ground — 2, 3 — —
1. Brake Pedal Position Sensor Malfunction 2. Stop Lamps Malfunction 3. Center High Mounted Stop Lamp Malfunction

Scan Tool Functions K9 Body Control Module – Data Display – Brake Pedal Position Data

Data Parameter Description
Brake Pedal Applied This data parameter will show the status of the brake pedal being applied as Active/Inactive
Brake Pedal Position Sensor This data parameter will show the status of the brake pedal being applied from a low percentage to a high percentage.

K219 Lighting Control Module – Control Functions – Exterior Lighting

Control Function Description
Left Stop Lamp This control function will control the left stop lamp on/off
Right Stop Lamp This control function will control the right stop lamp on/off
Center Stop Lamp This control function will control the center high mounted stop lamp (CHMSL) on/off

Circuit/System Description The B22 Brake Pedal Position Sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position sensor provides an analog voltage signal that will increase as the brake pedal is applied. The K9 Body Control Module (BCM) provides signal circuit 5361, 5 V reference circuit 5359, and low reference circuit 5360 to the brake pedal position sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM sends a serial data message to the K219 Lighting Control Module to illuminate the stop lamps. The Lighting Control Module responds by applying voltage to the left and right stop lamp control circuits as well as the center high mounted stop lamp (CHMSL) control circuit illuminating the left and right stop lamps and the CHMSL. Reference Information Schematic Reference Exterior Lights Schematics Connector End View Reference Master Electrical Component List Description and Operation Exterior Lighting Systems 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, verify the scan tool Brake Pedal Applied parameter changes between Active and Inactive while pressing and releasing the brake pedal. ⇒ If the parameter does not change Refer to Circuit/System Testing – Brake Pedal Position Sensor Malfunction. ⇓ If the parameter changes
  2. Verify the left and right stop lamps turn ON and OFF when commanding the Left/Right Stop Lamps ON and OFF with a scan tool. ⇒ If the stop lamps do not turn ON and OFF Refer to Circuit/System Testing – Stop Lamps Malfunction. ⇓ If the stop lamps turn ON and OFF
  3. Verify the center high mounted stop lamp turns ON and OFF when commanding the Center High Mounted Stop Lamp ON and OFF with a scan tool. ⇒ If the center high mounted stop does not turn ON and OFF Refer to Circuit/System Testing – Center High Mounted Stop Lamp Malfunction. ⇓ If the center high mounted stop turns ON and OFF
  4. A fault is not currently present and may be an intermittent condition Circuit/System Testing Brake Pedal Position Sensor Malfunction
  5. Ignition OFF, disconnect the connector at the B22 Brake Pedal Position Sensor, ignition ON.
  6. Verify a test lamp illuminates between low reference circuit terminal 1 and B+. ⇒ If the test lamp does not illuminate 2.1. Test circuit 5360 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 K9 Body Control Module. ⇓ If the test lamp illuminates
  7. Test for 4.8 – 5.2 V between voltage reference circuit terminal 2 and ground. ⇒ If less than 4.8 V 3.1. Test circuit 5359 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 3.2. Test circuit 5359 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 3.3. Replace the K9 Body Control Module. ⇒ If greater than 5.2 V 3.1. Test circuit 5359 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. 3.2. Replace the K9 Body Control Module. ⇓ If between 4.8 – 5.2 V
  8. Test for less than 1 V between the signal circuit terminal 3 and ground. ⇒ If 1 V or greater 4.1. Test circuit 5359 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 less than 1 V
  9. Install a 3 A fused jumper wire between voltage reference terminal 2 and signal circuit terminal 3.
  10. Verify the scan tool Brake Pedal Position Sensor parameter changes from 0% to 95% or greater. ⇒ If less than 95% 6.1. Test circuit 5361 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 6.2. Test circuit 5361 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 6.3. Replace the K9 Body Control Module. ⇓ If 95% or greater
  11. Test or replace the B22 Brake Pedal Position Sensor.
  12. Ignition/vehicle OFF, exterior lamps OFF, disconnect the appropriate component: E42L Rear Body Structure Stop Lamp - Left E42R Rear Body Structure Stop Lamp - Right
  13. Verify a test lamp illuminates between ground circuit terminal 1 and B+. ⇒ If the test lamp does not illuminate 2.1. Repair the open/high resistance on the ground circuit or ground connection. ⇓ If the test lamp illuminates
  14. Connect a test lamp between control circuit terminal 2 and ground, ignition ON.
  15. Verify the test lamp turns on and off when commanding the appropriate Stop Lamp ON and OFF with a scan tool. ⇒ If the test lamp is always OFF 4.1. Test the appropriate circuit for a short to ground: E42L Rear Body Structure Stop Lamp - Left = Circuit 7542 E42L Rear Body Structure Stop Lamp - Right = Circuit 7541 ⇒ If a short to ground is found, repair the fault on the circuit. ⇓ If a short to ground is not found 4.2. Test the appropriate circuit for an open/high resistance: E42L Rear Body Structure Stop Lamp - Left = Circuit 7542 E42L Rear Body Structure Stop Lamp - Right = Circuit 7541 ⇒ If an open/high resistance is found, repair the fault on the circuit. ⇓ If an open/high resistance is not found 4.3. Replace the K219 Lighting Control Module. ⇒ If the test lamp is always ON 4.1. Test the appropriate circuit for a short to voltage: E42L Rear Body Structure Stop Lamp - Left = Circuit 7542 E42L Rear Body Structure Stop Lamp - Right = Circuit 7541 ⇒ 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 K219 Lighting Control Module. ⇓ If the test lamp turns ON and OFF
  16. Replace the appropriate stop lamp. Center High Mounted Stop Lamp Malfunction
  17. Ignition OFF, exterior lamps OFF, disconnect the connector at the E6 High Mount Stop Lamp.
  18. Verify a test lamp illuminates between ground circuit terminal 1 and B+. ⇒ If the test lamp does not illuminate 2.1. Repair the open/high resistance on the ground circuit or ground connection. ⇓ If the test lamp illuminates
  19. Connect a test lamp between control circuit terminal 2 and ground, ignition ON.
  20. Verify the test lamp turns on and off when commanding the Center High Mounted Stop Lamp ON and OFF with a scan tool. ⇒ If the test lamp is always OFF 4.1. Test circuit 820 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. Test circuit 820 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. 4.3. Replace the K219 Lighting Control Module. ⇒ If the test lamp is always ON 4.1. Test circuit 820 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 K219 Lighting Control Module. ⇓ If the test lamp turns ON and OFF
  21. Replace the E6 High Mount Stop Lamp. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. Lighting Component Replacement Reference Control Module References for BCM replacement, programming, and setup