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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 22, Rear Defogger Relay Coil Shorted To Battery Or CCM Internal Open >> Testing
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DTC 22, Rear Defogger Relay Coil Shorted To Battery Or CCM Internal Open: Testing

  1. Turn ignition switch to OFF position. Remove rear defogger relay. Connect a test light between rear defogger relay connector terminal No. 2 and ground. Turn ignition switch to ON position. If test light illuminates, repair short to battery in rear defogger control circuit. If test light does not illuminate go to next step.
  2. Using DVOM, measure resistance between rear defogger relay terminals No. 5 and 2. If resistance is not 50-80 ohms, replace relay and go to next step. If resistance is 50-80 ohms, go to next step.
  3. Using DVOM, check for continuity between rear defogger relay terminals No. 1 and 2. If continuity is present, replace relay and go to next step. If continuity is not present, go to next step.
  4. Connect a test light between battery voltage and rear defogger relay connector terminal No. 2. Connect a jumper wire between Data Link Connector (DLC) terminals No. 12 and 5. Turn ignition switch to ON position. Press TRIP/ODO (next test) button on DIC until "1.4" displays on trip monitor. Press ENG/MET (next value) button on DIC until "9...0" displays on trip monitor. Display will cycle between "9...0" (off) and "9...1" (on). If test light illuminates when "9...1" is displayed, go to next step. If test light does not illuminate when "9...1" is displayed, go to step 6).
  5. No problem is present. 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.
  6. Check for open in rear defogger control circuit or for poor connections at CCM. If circuit and connections are okay, replace CCM.
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