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Home >> Oldsmobile >> 1998 >> Cutlass Base >> Repair and Diagnosis >> Accessories & Equipment >> Heated Glass/Defoggers >> Rear Window Defogger >> Testing >> Defogger System Tests >> Rear Defogger Operates Continuously

Rear Defogger Operates Continuously

  1. Remove rear defogger relay from Underhood Bussed Electrical Center (U/H BEC), located in left side of engine compartment. Install a known-good relay from U/H BEC. If rear defogger grid continues to warm, go to next step. If grid does not warm, go to step 3).
  2. Disconnect U/H BEC 68-pin Brown connector C3. If defogger grid continues to warm, go to step 4). If grid does not warm, go to step 9).
  3. Replace rear defogger relay. Recheck system operation.
  4. Disconnect LH Instrument Panel Bussed Electrical Center (LH I/P BEC) 30-pin Gray connector C2. LH I/P BEC is located under left side of instrument panel. Connect test light between LH I/P BEC connector C2 terminal C1 (Purple wire) and ground. If test light illuminates, go to next step. If test light does not illuminate, go to step 6).
  5. Repair short to voltage in circuit No. 293 (Purple wire) between U/H BEC connector C3 and LH I/P BEC connector C2. Recheck system operation.
  6. Disconnect LH I/P BEC 30-pin Black connector C3. Connect a test light between LH I/P BEC connector C3 terminal C12 (Black wire) and ground. If test light illuminates, go to next step. If test light does not illuminate, go to step 8).
  7. Repair short to voltage in circuit No. 293 (Black wire) between LH I/P BEC connector C3 and defogger grid. Recheck system operation.
  8. Replace LH I/P BEC. Recheck system operation.
  9. Using DVOM, check resistance between U/H BEC connector C3 terminal D5 (White wire) and ground. If resistance is infinite, go to next step. If resistance is not infinite, go to step 11).
  10. Replace U/H BEC. Recheck system operation.
  11. Disconnect A/C-heater control assembly 12-pin connector C2. Check resistance between A/C-heater control assembly connector C2 terminal "D" (White wire) and ground. If resistance is infinite, go to next step. If resistance is not infinite, go to step 13).
  12. Replace A/C-heater control assembly. See REMOVAL & INSTALLATION  . Recheck system operation.
  13. Repair short to ground in circuit No. 193 (White wire) between U/H BEC connector C3 and A/C-heater control assembly connector C2. Recheck system operation.
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