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Tahoe / Yukon Service Manual

Door Sill Illumination 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
4783 Control B15A8 11 1 1 —
7558 Control B191A 11 1 1 —
1150 Ground — 1 — —
1250 Ground — 1 — —
1. Door Sill Illumination Malfunction

Scan Tool Functions K9 Body Control Module – Data Display – Front Exterior Lighting Data

Data Parameter Description
Ambient Light Intensity This data parameter will show the status of the Ambient Light Sensor as a high LX value under bright ambient light conditions and a low LX value under dark ambient light conditions.

Circuit/System Description The Ambient Light Sensor provides a voltage signal that will vary between 0.2 and 4.9 V depending on outside lighting conditions. The door sill illumination lamps (B7G/S0M) become illuminated anytime the ignition is on during dark ambient light conditions. Reference Information Schematic Reference Interior Lights Schematics Connector End View Reference Master Electrical Component List Description and Operation Interior 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/vehicle in service mode.
  2. Verify the Ambient Light Intensity data parameter value changes appropriately: LX value increases with an incandescent light shined on the B10D Sun Load and Ambient Light and Security Indicator Sensor to simulate bright conditions. LX value decreases with a towel covering the B10D Sun Load and Ambient Light and Security Indicator Sensor to simulate dark conditions. ⇒ If the value does not change Refer to Circuit/System Testing – Ambient Light Sensor Malfunction ⇓ If the value changes
  3. Cover the Ambient Light Sensor to simulate dark ambient light conditions.
  4. Verify all E8 Door Sill Plate Lamps turn on and off when covering and uncovering the Ambient Light Sensor. ⇒ If the door sill plate lamps do not turn on and off Refer to Circuit/System Testing – Door Sill Malfunction ⇓ If the door sill plate lamps turn on and off
  5. A fault is not currently present and may be an intermittent condition. Circuit/System Testing Ambient Light Sensor Malfunction
  6. Ignition OFF, disconnect the connector at the B10D Sun Load and Ambient Light and Security Indicator Sensor, ignition on.
  7. Verify a test lamp illuminates between low reference terminal 6 and B+. ⇒ If the test lamp does not illuminate 2.1. Test circuit 407 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
  8. Test for 4.8 V – 5.2 V between signal circuit terminal 3 and ground. ⇒ If less than 4.8 V 3.1. Test circuit 278 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 278 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 278 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 V – 5.2 V
  9. Replace the B10D Sun Load and Ambient Light and Security Indicator Sensor. Door Sill Malfunction
  10. Ignition/vehicle off, disconnect the appropriate connector at the K9 Body Control Module: E8A Front Side Door Sill Plate Illumination Lamp – Left = Connector X1 E8B Front Side Door Sill Plate Illumination Lamp – Right = Connector X1 E8Q Rear Side Door Sill Plate Illumination Lamp – Left = Connector X7 E8R Rear Side Door Sill Plate Illumination Lamp – Right = Connector X7
  11. Connect a 3 A fused jumper wire between the appropriate control circuit terminal and B+: E8A Front Side Door Sill Plate Illumination Lamp – Left = Terminal 4 X1 E8B Front Side Door Sill Plate Illumination Lamp – Right = Terminal 4 X1 E8Q Rear Side Door Sill Plate Illumination Lamp – Left = Terminal 24 X7 E8R Rear Side Door Sill Plate Illumination Lamp – Right = Terminal 24 X7
  12. Verify the appropriate door sill lamps turn on and off when connecting and disconnecting the jumper wire. ⇒ If a door sill lamp is always off and the jumper fuse is OK. 3.1. Test the appropriate ground circuit at the door sill lamp for an open/high resistance: E8A Front Side Door Sill Plate Illumination Lamp – Left = Circuit 1150 E8B Front Side Door Sill Plate Illumination Lamp – Right = Circuit 1250 E8Q Rear Side Door Sill Plate Illumination Lamp – Left = Circuit 1150 E8R Rear Side Door Sill Plate Illumination Lamp – Right = Circuit 1250 ⇒ If an open/high resistance is found, repair the fault on the circuit or ground connection. ⇓ If an open/high resistance is not found. 3.2. Test the appropriate control circuit for an open/high resistance: E8A Front Side Door Sill Plate Illumination Lamp – Left = Circuit 7558 E8B Front Side Door Sill Plate Illumination Lamp – Right = Circuit 7558 E8Q Rear Side Door Sill Plate Illumination Lamp – Left = Circuit 4783 E8R Rear Side Door Sill Plate Illumination Lamp – Right = Circuit 4783 ⇒ 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 appropriate door sill lamp. ⇒ If a door sill lamp is always off and the jumper fuse is open 3.1. Test the appropriate circuit for a short to ground: E8A Front Side Door Sill Plate Illumination Lamp – Left = Circuit 7558 E8B Front Side Door Sill Plate Illumination Lamp – Right = Circuit 7558 E8Q Rear Side Door Sill Plate Illumination Lamp – Left = Circuit 4783 E8R Rear Side Door Sill Plate Illumination Lamp – Right = Circuit 4783 ⇒ If a short to ground is found, repair the fault on the circuit. ⇓ If a short to ground is not found. 3.2. Replace the appropriate door sill lamp. ⇒ If a door sill lamp is always on 3.1. Test the appropriate circuit for a short to voltage: E8A Front Side Door Sill Plate Illumination Lamp – Left = Circuit 7558 E8B Front Side Door Sill Plate Illumination Lamp – Right = Circuit 7558 E8Q Rear Side Door Sill Plate Illumination Lamp – Left = Circuit 4783 E8R Rear Side Door Sill Plate Illumination Lamp – Right = Circuit 4783 ⇒ 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 appropriate door sill lamp. ⇓ If the door sill lamps turn on and off
  13. Replace the K9 Body Control Module. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. Lighting Component Replacement Reference Control Module References for BCM replacement, programming, and setup