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 MANUALSCHEVROLET1998SUBURBAN K2500, 7.4 J, PART TIMEREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 609 (LIGHTING SYSTEMS)DIAGNOSTIC INFORMATION AND PROCEDURESDTC B2645: AMBIENT LIGHT SENSOR CIRCUITTEST DESCRIPTION
1998 Chevrolet Suburban K2500, 7.4 J, Part Time
Test Description
1998 Chevrolet Suburban K2500, 7.4 J, Part TimeSECTION Test Description
WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
The number below refers to the step number on the diagnostic table.
- 2: This step tests the ambient light sensor reference voltage circuit for a short to battery positive voltage.
DTC B2645
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics Connector End View Reference: Master Electrical Component List |
||||
| 1 | Did you perform the Diagnostic System Check? | - | Go to Step 2 | Go to Diagnostic System Check - Lighting Systems |
| 2 |
|
12 V | Go to Step 4 | Go to Step 3 |
| 3 | Inspect the ambient light sensor return circuit for a short to battery positive voltage. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 7 | Go to Step 6 |
| 4 | Inspect the ambient light sensor reference voltage circuit for a short to battery positive voltage. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 7 | Go to Step 5 |
| 5 |
IMPORTANT:
Perform the set up procedure for the body control module (BCM). Refer to Body Control Module (BCM) Programming/RPO Configuration
in Body Control Systems. Replace the body control module. Refer to Body Control Module Replacement
in Body Control System.Did you complete the replacement? |
- | Go to Step 7 | - |
| 6 | Replace the ambient light sensor. Refer to Daytime Running Lamps (DRL) Ambient Light Sensor Replacement . Did you complete the replacement? |
- | Go to Step 7 | - |
| 7 |
|
- | 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.