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Home >> Oldsmobile >> 1999 >> Bravada >> Repair and Diagnosis >> Body & Frame >> Body, Cab Control Systems >> Body Control Modules >> Diagnostic Tests >> DTC B2647: Ambient Light Sensor Circuit Low >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform BCM diagnostic system check. See BCM DIAGNOSTIC SYSTEM CHECK  under SYSTEM TESTS. After performing system check, go to next step.
  2. Turn ignition on. Place drop light near ambient light sensor. Using DVOM connected to ground, measure voltage (backprobe) at Purple 16-pin BCM connector terminal A6. See Figure . If reading is one volt or more with drop light near ambient light sensor, go to step 8). If reading is less than one volt with drop light near ambient light sensor, go to next step.
  3. Turn ignition off. Disconnect Purple 16-pin BCM connector. See COMPONENT LOCATIONS  . Remove connector comb from Purple BCM connector. Disconnect ambient light sensor connector. Using DVOM, measure resistance of White wire between ambient light sensor connector terminal "B" and Purple 16-pin BCM connector terminal A6. See WIRING DIAGRAMS  . If resistance is 5 ohms or less, go to next step. If resistance is more than 5 ohms, go to step 5).
  4. Using test light connected to battery voltage, backprobe ambient light sensor connector terminal "B" (White wire). If test light illuminates, go to step 6). If test light does not illuminate, go to step 7).
  5. Repair open in White wire between ambient light sensor connector terminal "B" and Purple 16-pin BCM connector terminal A6. After repairs, go to step 9).
  6. Repair short to ground in White wire between ambient light sensor connector terminal "B" and Purple 16-pin BCM connector terminal A6. After repairs, go to step 9).
  7. Replace ambient light sensor. Reconnect all components and wiring. After repairs, go to step 9).
  8. Replace BCM. See BODY CONTROL MODULE (BCM)  under REMOVAL & INSTALLATION. Program BCM and perform relearn procedure. See PROGRAMMING  . After programming module, go to next step.
  9. Clear DTCs. After clearing DTCs, perform BCM diagnostic system check. See BCM DIAGNOSTIC SYSTEM CHECK  under SYSTEM TESTS.
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