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 MANUALSCHEVROLET2001CAVALIER LS, 2.4 TREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 17 (BODY CONTROL MODULES)DIAGNOSTIC TESTSDTC B2648: AMBIENT LIGHT SENSOR CIRCUIT HIGHTESTING
2001 Chevrolet Cavalier LS, 2.4 T
DTC B2648: Ambient Light Sensor Circuit High: Testing
2001 Chevrolet Cavalier LS, 2.4 TSECTION Testing
WARNING: This page is about a different car, the 2000 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.
- If BCM diagnostic system check has been performed, go to next step. If BCM diagnostic system check has not been performed, go to BODY CONTROL MODULE DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM.
- Connect scan tool to Data Link Connector (DLC). Turn ignition on. Using scan tool, select BCM INPUTS and monitor AMBIENT LIGHT SENSOR data on scan tool. If scan tool displays 0.1-2.5 volts, go to DIAGNOSTIC AIDS . If scan tool does not display 0.1-2.5 volts, go to next step.
- Turn ignition off. Disconnect ambient light sensor connector. Ambient light sensor is located on top of the instrument panel in the defroster grille. Turn ignition on. Monitor AMBIENT LIGHT SENSOR data on scan tool. If scan tool displays less than 0.1 volt, go to next step. If scan tool displays greater than 0.1 volt, go to step 9.
- Turn ignition off. Connect a 3-amp jumper wire between ambient light sensor connector terminals "A" (Yellow/Black wire) and "B" (Light Green/Black wire). Turn ignition on. Monitor AMBIENT LIGHT SENSOR data. If scan tool displays greater than 3.5 volts, go to next step. If scan tool displays less than 3.5 volts, go to step 7.
- Remove fused jumper. Using DVOM, measure voltage between ambient light sensor connector terminals. If voltage is greater than 5 volts, go to next step. If voltage is less than 5 volts, go to step 10.
- Check for short to voltage in Yellow/Black wire between BCM and ambient light sensor. If circuit is okay, go to step 11. If faulty circuit is found and repaired, go to step 14.
- Check for short to ground in Yellow/Black wire between BCM and ambient light sensor. If circuit is okay, go to next step. If faulty circuit is found and repaired, go to step 14.
- Check for short to ground in Light Green/Black wire between BCM and ambient light sensor. If circuit is okay, go to step 11. If faulty circuit is found and repaired, go to step 14.
- Check for short to voltage in Light Green/Black wire between BCM and ambient light sensor. If circuit is okay, go to step 11. If faulty circuit is found and repaired, go to step 14.
- Check for poor connections at ambient light sensor connector. If faulty connections are found and repaired, go to step 14. If connections are okay, go to step 12.
- Check for poor connections at BCM connector C1. If faulty connections are found and repaired, go to step 14. If connections are okay, go to step 13.
- Replace ambient light sensor. After repairs, go to step 14.
- Replace BCM and program. See BODY CONTROL MODULE (BCM) under REMOVAL & INSTALLATION. See BCM PROGRAMMING/RPO CONFIGURATION under PROGRAMMING. After repairs, go to next step.
- Turn ignition off. Reinstall all components and connectors. Turn ignition on. Clear DTCs. If DTC resets, go to step 2.
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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.