Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2009TAHOE BASE, 4.8 CREPAIR AND DIAGNOSIS (SINGLE PAGE)ACCESSORIES & EQUIPMENTHEADLIGHTSLIGHTING SYSTEMSDIAGNOSTIC INFORMATION AND PROCEDURESCOURTESY LAMPS MALFUNCTIONCIRCUIT/SYSTEM TESTING
2009 Chevrolet Tahoe Base, 4.8 C
Circuit/System Testing
2009 Chevrolet Tahoe Base, 4.8 CSECTION Circuit/System Testing
Courtesy Lamp Malfunction
- Ignition OFF, disconnect the harness connector at the appropriate lamp.
- Test for less than 5.0 ohms between the ground circuit terminal B and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Connect a test lamp between the control circuit terminal listed below and the ground.
- Courtesy/Reading Lamp terminal C
- Dome/Reading Lamp terminal A
- Sunshade Lamps terminal A
- Dome Lamp terminal A
- Cargo Lamp terminal A
- Ignition ON, command the Courtesy Lamps output control ON and OFF with the scan tool. The test lamp should turn ON and OFF.
- If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
- If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
- If all circuits test normal, test or replace the appropriate bulb.
Door Open Switch Malfunction - Front
- Ignition OFF, disconnect the harness connector at the inoperative door latch assembly.
- Test for less than 10.0 ohms between the appropriate ground circuit terminal listed below and ground.
- Drivers Door terminal 8
- Passenger Door terminal 3
- If greater than the specified range, test the ground circuit for an open/high resistance. If the circuit tests normal, replace the Door Lock/Window Switch.
- Ignition ON, verify the scan tool Door Open Switch parameter is CLOSED.
- If the scan tool displays OPEN, test the appropriate signal circuit terminal listed below for a short to ground. If the circuit tests normal, replace the Door Lock/Window Switch.
- Drivers Door terminal 7
- Passenger Door terminal 2
- If the scan tool displays OPEN, test the appropriate signal circuit terminal listed below for a short to ground. If the circuit tests normal, replace the Door Lock/Window Switch.
- Install a 3A fused jumper wire between the appropriate signal circuit terminal listed below and ground. Verify the scan tool Door Open Switch parameter is OPEN.
- Drivers Door terminal 7 to terminal 8
- Passenger Door terminal 2 to terminal 3
- If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the Door Lock/Window Switch.
- If all circuits test normal, replace the inoperative door latch assembly.
Door Open Switch Malfunction - Rear
- Ignition OFF, disconnect the harness connector at the inoperative rear door latch assembly.
- Interior lamps OFF, test for less than 10.0 ohms between the appropriate ground circuit terminal listed below and ground.
- Left rear door latch assembly ground circuit terminal 6
- Right rear door latch assembly ground circuit terminal 3
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Ignition ON, verify a test lamp illuminates between the appropriate door open switch signal circuit terminal listed below and ground.
- Left rear door open switch signal circuit terminal 5
- Right rear door open switch signal circuit terminal 2
- If the test lamp does not illuminate, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
- Install a 3A fused jumper wire between the appropriate signal circuit terminal listed below and ground. Verify the courtesy lamps illuminate and remain illuminated.
- Left rear door open switch signal circuit terminal 5
- Right rear door open switch signal circuit terminal 2
- If the courtesy lamps do not remain illuminated, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.
- If all circuits test normal, replace the inoperative rear door latch assembly.
Dome/Interior Lamp Switch Malfunction
- Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
- Test for less than 5.0 ohms between the ground circuit terminal 8 and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Ignition ON, verify the scan tool Ctsy. Lamp Actv. Reason parameter is Off.
- If the parameter is Manual or Manual Defeat, test the appropriate signal circuit terminal for a short to ground. If the circuit tests normal, replace the BCM.
- Manual terminal 12
- Manual Defeat terminal 9
- If the parameter is Manual or Manual Defeat, test the appropriate signal circuit terminal for a short to ground. If the circuit tests normal, replace the BCM.
- Install a 3A fused jumper wire between the signal circuit terminal 12 and the ground circuit terminal 8. Verify the scan tool Ctsy. Lamp Actv. Reason parameter is Manual.
- If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
- Install a 3A fused jumper wire between the signal circuit terminal 9 and the ground circuit terminal 8. Verify the scan tool Ctsy. Lamp Actv. Reason parameter is Manual Defeat.
- If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
- If all circuits test normal, test or replace the headlamp and panel dimmer switch.
Outside Rearview Mirror Illumination Malfunction
- Disconnect the harness connector at the appropriate exterior illumination lamp bulb.
- Ignition ON, verify that a test lamp illuminates between the exterior illumination lamp supply circuit terminal and ground.
- If the test lamp does not illuminate, test the exterior illumination lamp supply circuit for a short to ground or an open/high resistance.
- Connect a test lamp between the low side control circuit terminal and the exterior illumination lamp supply circuit terminal.
- Command the Puddle/Courtesy Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
- If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the inoperative door switch.
- If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the inoperative door switch.
- If all circuits test normal, test or replace the appropriate bulb.
Reading Lamps Malfunction
- Ignition OFF, disconnect the X3 harness connector at the BCM.
- Verify a test lamp illuminates between the IS LPS fuse B+ circuit terminal 2 and ground.
- If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
- Reconnect the X3 harness connector at the BCM.
- Disconnect the harness connector at the inoperative courtesy/reading lamp assembly.
- Scan tool OFF, doors CLOSED, interior lamps OFF, test for less than 5.0 ohms between the listed ground circuit terminal below and ground.
- Verify a test lamp illuminates between the control circuit terminal C and ground.
- Courtesy/Reading Lamp terminal C
- Dome/Reading Lamp terminal A
- If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
- Remove the IS LPS fuse and verify the test lamp turns OFF.
- If the test lamp remains illuminated, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
- If all circuits test normal, replace the inoperative courtesy lamp assembly.
Vanity Mirrors Malfunction
- Ignition OFF, disconnect the harness connector at the appropriate vanity mirror lamp.
- Test for less than 5.0 ohms between the ground circuit terminal B and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Ignition ON, verify that a test lamp illuminates between the inadvertent power supply circuit terminal A and ground.
- If the test lamp does not illuminate, test the inadvertent power supply circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
- Connect the harness connector at the vanity mirror lamp.
- Remove the IS LPS fuse and verify the test lamp turns OFF.
- If the test lamp remains illuminated, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
- If all circuits test normal, replace the inoperative vanity mirror.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.