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Home >> Ford >> 1997 >> Escort Base, Standard >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Heated Glass/Defoggers >> Rear Window Defogger System >> Testing >> System Testing
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System Testing

  1. Check 30-amp DEFOG fuse in main fuse panel located on driver's side of engine compartment. If fuse is okay, reinstall fuse and go to step 5). If fuse is blown, go to next step.
  2. Turn ignition off. Disconnect defogger relay located in the interior relay panel. Disconnect 13-pin interior fuse panel connector. Measure resistance between ground and defogger relay connector terminal No. 30 (Black/Pink wire). See Fig 1 . Resistance should be greater than 10 k/ohms. If resistance is greater than 10 k/ohms, go to next step. If resistance is not greater than 10 k/ohms, repair Black/Pink wire between relay connector and interior fuse panel connector. See WIRING DIAGRAM  .
    Fig 1: Identifying Defogger Relay Connector Terminals
    G97D28061Courtesy of FORD MOTOR CO.
  3. Disconnect 3-pin defogger switch and light connector. See INTEGRATED CONTROL PANEL  under REMOVAL & INSTALLATION. Measure resistance between ground and defogger relay connector terminal No. 87 (Black/Blue wire). See Fig 1 . Resistance should be greater than 10 k/ohms. If resistance is greater than 10 k/ohms, go to next step. If resistance is not greater than 10 k/ohms, repair Black/Blue wire. See WIRING DIAGRAM  .
  4. Test defogger relay. See DEFOGGER RELAY TEST. If defogger relay is okay, remove ICP and send to authorized Ford repair facility. See INTEGRATED CONTROL PANEL  under REMOVAL & INSTALLATION. If defogger relay is not okay, replace relay.
  5. Disconnect rear window defogger grid connector. Turn ignition on. Turn rear defogger on. Measure voltage between ground and rear window grid connector Black/Blue wire. Voltage should be greater than 10 volts. If voltage is greater than 10 volts, go to next step. If voltage is not greater than 10 volts, go to step 7).
  6. Turn ignition off. Measure resistance between ground and rear window defogger grid connector Black wire. Resistance should be less than 5 ohms. If resistance is less than 5 ohms, check rear window defogger grid. See GRID FILAMENT TEST  . If resistance is greater than 5 ohms, repair Black wire between connector and ground. See WIRING DIAGRAM  .
  7. Test defogger relay. See DEFOGGER RELAY TEST  . If defogger relay is okay, go to next step. If defogger relay is not okay, replace relay.
  8. Turn ignition on. Measure voltage between ground and defogger relay connector terminals No. 86 (Black/Yellow wire) and No. 30 (Black/Pink wire). Voltage should be greater than 10 volts at both locations. If voltage is greater than 10 volts, go to next step. If voltage is not greater than 10 volts, repair circuit in question. See WIRING DIAGRAM  .
  9. Turn ignition off. Disconnect 8-pin interior fuse panel connector. Measure resistance between 8-pin interior fuse panel connector Black/Red wire and defogger relay connector No. 85 (Black/Red wire). Resistance should be less than 5 ohms. If resistance is less than 5 ohms, go to next step. If resistance is not less than 5 ohms, repair Black/Red wire between fuse panel connector and relay connector. See WIRING DIAGRAM  .
  10. Disconnect 3-pin defogger switch and light connector. See INTEGRATED CONTROL PANEL  under REMOVAL & INSTALLATION. Disconnect 11-pin interior fuse panel connector. Measure resistance between interior fuse panel connector White/Red wire and defogger switch and light harness connector White/Red wire. Resistance should be less than 5 ohms. If resistance is less than 5 ohms, go to next step. If resistance is not less than 5 ohms, repair White/Red wire between fuse panel connector and switch and light connector. See WIRING DIAGRAM  .
  11. Measure resistance between ground and defogger switch and light harness connector Black wire. Resistance should be less than 5 ohms. If resistance is less than 5 ohms, go to next step. If resistance is not less than 5 ohms, repair Black wire between ground and switch and light connector. See WIRING DIAGRAM  .
  12. Measure resistance between defogger switch and light connector terminals No. 1 and 3 (two outside terminals). With switch pressed, resistance should be less than 5 ohms. With switch released, resistance should be greater than 10 k/ohms. If resistances are as specified, replace safety belt warning chime. If resistances are not as specified, remove ICP and send to authorized Ford repair facility. See INTEGRATED CONTROL PANEL  under REMOVAL & INSTALLATION.
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