* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit
Testing/Circuit Testing)
* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Connector Repairs/Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/General
Electrical Diagnostic Procedures/Circuit Testing/Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Wiring
Repairs/Wiring Repairs)
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the DRL resistor.
2. Connect a test lamp between the control circuit terminal C and B+.
3. Command the DRL ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
锟斤拷 If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.
锟斤拷 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 BCM.
4. Ignition OFF, connect the harness connector at the DRL resistor.
5. Disconnect the harness connector at the inoperative headlamp assembly.
6. Connect a test lamp between the signal circuit terminal D and B+.
7. Command the DRL ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
锟斤拷 If the test lamp is always ON, test the signal circuit for a short to ground. If the circuit tests normal, replace the DRL resistor.
锟斤拷 If the test lamp is always OFF, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the
DRL resistor.
8. Connect a test lamp between the signal circuit terminal B and B+.
9. Command the DRL ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
锟斤拷 If the test lamp is always ON, test the signal circuit for a short to ground. If the circuit tests normal, replace the DRL resistor.
锟斤拷 If the test lamp is always OFF, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the
DRL resistor.
10. If all circuits test normal, replace the appropriate headlamp.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Headlamp Replacement (Cadillac Escalade) (See: Lighting and Horns/Headlamp/Service and Repair/Removal and Replacement/Headlamp
Replacement (Cadillac Escalade))Headlamp Replacement (GMC Yukon Two-mode Hybrid) (See: Lighting and Horns/Headlamp/Service
and Repair/Removal and Replacement/Headlamp Replacement (GMC Yukon Two-mode Hybrid))Headlamp Replacement (Yukon) (See:
Lighting and Horns/Headlamp/Service and Repair/Removal and Replacement/Headlamp Replacement (Yukon))Headlamp Replacement
(Chevrolet Tahoe Two-mode Hybrid) (See: Lighting and Horns/Headlamp/Service and Repair/Removal and Replacement/Headlamp
Replacement (Chevrolet Tahoe Two-mode Hybrid))Headlamp Replacement (Tahoe, Avalanche) (See: Lighting and Horns/Headlamp/Service
and Repair/Removal and Replacement/Headlamp Replacement (Tahoe, Avalanche))Headlamp Replacement (Escalade PLATINUM) (See:
Lighting and Horns/Headlamp/Service and Repair/Removal and Replacement/Headlamp Replacement (Escalade Platinum))Headlamp
Replacement (Non HID) (See: Lighting and Horns/Headlamp/Service and Repair/Removal and Replacement/Headlamp Replacement (Non
HID))
* Underhood Electrical Center or Junction Block Replacement (See: Maintenance/Fuses and Circuit Breakers/Fuse Block/Service and
Repair/Removal and Replacement/Underhood Electrical Center or Junction Block Replacement)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for BCM replacement, setup, and programming
With RPO Code X88, Z75, and Z88
DTC B2600 (With X88, Z75, and Z88)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
