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Home >> Chevrolet >> 1996 >> Corvette Base, 2D Convertible, 5.7 5 >> Repair and Diagnosis >> Body & Frame >> Body, Cab Control Systems >> Central Control Module >> Diagnosing & Repairing CCM DTCS >> DTC 72, LCD Dimming Output Circuit Open Or Shorted To Ground >> Testing
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DTC 72, LCD Dimming Output Circuit Open Or Shorted To Ground: Testing

  1. Cover ambient light sensor on Driver Information Center (DIC) with dark tape to simulate darkness. Turn parking lights on and operate dimmer control. If instrument panel and cluster lighting does not dim and brighten with dimmer control, repair dimmer control. Go to next step after repairs. If instrument panel and cluster lighting dims and brightens with dimmer control, go to next step.
  2. Turn parking lights off. Turn ignition switch to OFF position. Remove radio control head and heater/air conditioning control head (if equipped). Disconnect connectors from both control heads. Connect a test light between radio control head harness connector terminal No. 3 and battery voltage. Turn parking lights on and operate dimmer control. Move dimmer control through full range and observe test light. If test light brightness changes as dimmer control is operated, go to step 4). If test light stays on steady, repair short to ground in LCD dim control circuit. If test light does not illuminate, go to next step.
  3. Clear DTCs. Reconnect radio control head connector. Turn parking lights on and operate dimmer control. Check for DTC 72. If DTC 72 sets, replace radio control head. If DTC 72 does not set, reconnect heater/air conditioning control head connector. Turn parking lights on and operate dimmer control. Check for DTC 72. If DTC 72 sets, replace heater/air conditioning control head. If DTC 72 does not set, go to next step.
  4. Check wiring and connections for intermittents. Clear DTCs. Turn parking lights on and operate dimmer control. Check for DTC 72. If DTC 72 sets, replace CCM. If DTC 72 does not set, go to next step.
  5. Check for poor connections at CCM and radio control head and heater/air conditioning control head. Poor connections could cause an open or an intermittent fault. If code is set as history, problem may be intermittent. Try to recreate fault while performing test by wiggling wiring and connectors. Check for poor connections at all connectors that may be causing intermittent condition.
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