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 MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1746 (LIGHTING SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC B2602TEST DESCRIPTION
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Test Description
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Test Description
WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
The numbers below refer to the step numbers on the diagnostic table.
- 2: Listen for an audible click when the DRL relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
- 3: This step tests for voltage at the coil side of the DRL relay.
- 4: This step verifies that the BCM is providing ground to the DRL relay.
- 5: This step tests if ground is constantly being applied to the DRL relay.
DTC B2602
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle |
| 2 |
|
Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 |
| 3 |
|
Go to Step 4 | Go to Step 10 |
| 4 |
|
Go to Step 8 | Go to Step 5 |
| 5 | Does the test lamp remain illuminated with each command? | Go to Step 7 | Go to Step 6 |
| 6 | Test the control circuit of the DRL relay for an open. Refer to Circuit Testing
and Wiring Repairs
. Did you find and correct the condition? |
Go to Step 13 | Go to Step 9 |
| 7 | Test the control circuit of the DRL relay for a short to ground. Refer to Circuit Testing
and Wiring Repairs
. Did you find and correct the condition? |
Go to Step 13 | Go to Step 9 |
| 8 | Inspect for poor connections at the DRL relay. Refer to Testing for Intermittent Conditions and Poor Connections
and Connector Repairs
. Did you find and correct the condition? |
Go to Step 13 | Go to Step 11 |
| 9 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections
and Connector Repairs
. Did you find and correct the condition? |
Go to Step 13 | Go to Step 12 |
| 10 | Repair an open, high resistance, or short to ground in the coil side battery positive voltage circuit of the DRL relay. Refer to Circuit Testing
and Wiring Repairs
. Did you complete the repair? |
Go to Step 13 | - |
| 11 | Replace the DRL relay. Did you complete the replacement? |
Go to Step 13 | - |
| 12 | Replace the BCM. Refer to Control Module References
for replacement, setup, and programming. Did you complete the replacement? |
Go to Step 13 | - |
| 13 |
|
Go to Step 2 | System OK |
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.