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.
2002 GMC C3500 HD 6.5 F, AutomaticFACTORY OEM SERVICE PROCEDURE
Lighting DTCS
LIGHTING DIAGNOSTIC TROUBLE CODE (DTC) LIST
| DTC | Description |
|---|---|
| DTC B1397 | 5 Volt Reference Output Circuit Voltage Low |
| DTC B1398 | 5V Reference Circuit Voltage High |
| DTC B1480 | Courtesy Lamps Supply Voltage Circuit Voltage Low |
| DTC B2527 | Front Fog Lamp Switch Signal Circuit Is Shorted To Ground |
| DTC B2577 | Headlamp Relay Coil Supply Voltage Circuit Shorted To Ground |
| DTC B2585 | Interior Park Lamps Supply Voltage Circuit |
| DTC B2613 | Instrument Panel Lamp Supply Voltage Circuit Is Shorted To Battery Voltage |
| DTC B2617 | Courtesy Lamp Relay Coil Control Circuit Is Open Or Shorted To Ground |
| DTC B2618 | Courtesy Lamp Relay Coil Control Circuit Is Open Or Shorted To Ground |
| DTC B2642 | Ground Illumination Relay Control Circuit Is Open Or Shorted To Ground |
| DTC B2643 | Ground Illumination Relay Control Circuit Is Shorted To Battery Voltage |
| DTC B2647 | Ambient Light Sensor Input Voltage Low |
| DTC B2648 | Ambient Light Sensor Input Voltage High |
Factory Service Tools
Use the Manual With the Right Hardware
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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.