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DTC B2648: Ambient Light Sensor Signal Short To Battery: Testing

  1. If Body Control Module (BCM) diagnostic system check has been performed, go to next step. If Body Control Module (BCM) diagnostic system check has not been performed, go to BODY CONTROL MODULE (BCM) DIAGNOSTIC SYSTEM CHECK  under SYSTEM TESTS.
  2. Connect scan tool to Data Link Connector (DLC), located to left of steering column. Turn ignition on. Using scan tool, select LAMP STATUS then PHOTOCELL VOLTAGE. If voltage is not .5-4.5 volts, go to next step. If voltage is .5-4.5 volts, go to DIAGNOSTIC AIDS  .
  3. Turn ignition off. Disconnect ambient light sensor. Turn ignition on. Using scan tool, check PHOTOCELL VOLTAGE. If voltage is .5 volt or less, go to next step. If voltage is more than .5 volt, go to step  5 .
  4. Check for open or short to ground on Light Green/Black wire between BCM connector C2 terminal B2 and ambient light sensor terminal "A". See Figure . Check for open or short to ground on Yellow/Black wire between BCM connector C2 terminal A3 and ambient light sensor terminal "B". If circuits are okay, go to step  6 . If open or short to ground exists, repair as necessary. After repair, go to step  10 .
  5. Turn ignition on. Check for short to power on Light Green/Black wire between BCM connector C2 terminal B2 and ambient light sensor terminal "A". Check for short to power on Yellow/Black wire between BCM connector C2 terminal A3 and ambient light sensor terminal "B". If circuits are okay, go to step  7 . If short to power exists, repair as necessary. After repair, go to step  10 .
  6. Check ambient light sensor and connector terminals for damage and poor connections. If no problem is found, go to step  8 . If connections are poor, repair as necessary. After repair, go to step  10 .
  7. Check BCM and harness connector terminals for damage and poor connections. If no problem is found, go to step  9 . If connections are poor, repair as necessary. After repair, go to step  10 .
  8. Replace sensor. Go to step  10 .
  9. Replace BCM. See BODY CONTROL MODULE (BCM)  under REMOVAL & INSTALLATION. Program BCM. See BODY CONTROL MODULE (BCM)  under PROGRAMMING. After repair, go to next step.
  10. Reconnect all disconnected components and connectors. Clear DTCs. Operate vehicle under conditions that set DTC. If DTC resets, go to step  2 . If DTC does not reset, system is okay.
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