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9B-43 Lighting Systems:
Action Taken When the DTC Sets
The BCM turns off the DRL relay control for the
remainder of the ignition cycle.
Conditions for Clearing the DTC
• A current DTC B2600 clears when the BCM no longer
detects a short to battery positive voltage in the
control circuit on the park lamp relay.
• 100 consecutive ignition cycles have been recorded
without the DTC being detected.
• Using a scan tool can clear the DTC.
Diagnostic Aids
• Check both the LH and RH headlamps for proper
operation
• Check both the LH High Beam, LH Low Beam and RH
High Beam and RH Low Beam Head lamp fuses
located in the underhood fuseblock.
• If DTC B2602 also sets, perform the diagnostics for
DTC B2602 before performing diagnostics for DTC
B2600
Reference Information
Schematic Reference
"Headlights/Daytime Running Lights (DRL) Schematics"
Connector End View Reference
"Lighting Systems Connector End Views"
Electrical Information Reference
• "Circuit Testing: "
• "Connector Repairs: "
• "Testing for Intermittent Conditions and Poor
Connections: "
• "Wiring Repairs: "
Scan Tool Reference
• "Scan Tool Data Definitions - Lighting"
• "Scan Tool Data List - Lighting"
• "Scan Tool Output Controls - Lighting"
Circuit/System Verification
Ignition ON, command the DRL ON and OFF with a scan
tool, observe the DRL. The DRLs should turn ON and
OFF with each command.
Circuit/System Testing
1. Ignition OFF, disconnect the C2 DRL harness
connector at the BEC.
2. Connect a test lamp between the control circuit
terminal 38 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.
➢ If the test lamp is always ON, test the control circuit
for a short to ground. If the circuit tests normal,
replace the BCM.
➢ 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 C2 DRL harness
connector at the BEC. Disconnect the harness
connector at the inoperative low beam head lamps.
5. Test for less than 1.0 ohm of resistance between the
appropriate head lamp ground circuit terminal 2 and
ground.
➢ If greater than the specified range, test the ground
circuit for an open/high resistance.
6. Connect a test lamp between the control circuit
terminal 1 and ground.
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.
➢ If the test lamp is always ON, test the control circuit
for a short to voltage. If the circuit tests normal,
replace the BEC.
➢ If the test lamp is always OFF and the circuit fuse is
good, test the control circuit for an open/high
resistance. If the circuit tests normal, test or replace
the BEC.
➢ If the test lamp is always OFF and the circuit fuse is
open, test the control circuit for a short to ground. If
the circuit tests normal, replace the appropriate
head lamp.
8. If all circuits test normal, replace the appropriate
head lamp.
Repair Instructions
Perform the "Diagnostic Repair Verification - Vehicle
Diagnostic Information: " after completing the diagnostic
procedure
• "Headlamp Replacement"
• "Control Module References: " for BCM replacement,
setup, and programming
• "Underhood Electrical Center or Junction Block
Replacement: "
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Table of Contents
Troubleshooting
