Cutlass V6-191 3.1L VIN M SFI (1998)
Heated Glass Element: Diagnostic Trouble Code Tests and Associated Procedures
Circuit Operation
When the Rear Defogger Switch is pressed, voltage is applied to the solid state Timing Circuit and the ON indicator. The Timing Circuit grounds circuit
193 which energizes the Rear Defogger Relay to close the relay switch contacts. This applies voltage to circuit 293 and the Rear Defogger Grid. The rear
window becomes warm to remove the condensation from the surface of the window.
The contacts in the Timing Circuit stay closed until the Rear Defogger Switch is pressed again. the timer cycle is complete, or the Ignition Switch is
turned to the OFF position.
The first time the Rear Defogger Switch is pressed. he Timing Circuit allows the Rear Defogger to operate for approximately ten minutes. Each time
after that when the Rear Defogger Control Switch is pressed, the Timing Circuit operates for approximately five minutes. The Timing Circuit resets to
ten minutes when the Ignition Switch is turned to the OFF position.
Troubleshooting Hints
1. Check RR DEFOG and HTR A/C IGN Fuses by visual inspection.
2. If one or more of the grid lines do not heat.
3. If the Panel Lamp is inoperable with the Headlamp Switch in PARK or HEAD check bulb and wiring to bulb.
4. If Rear Defogger ON Indicator lights continuously or does not light at all, but Rear Defogger operates normally. replace the heater A/C Control
Assembly. Refer to Control Assembly in Air Conditioning. See: Heating and Air Conditioning
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Check for a broken (or partially broken) wire inside of the insulation which could cause system failure but prove GOOD in a continuity/voltage
check (Refer to Troubleshooting Procedures).
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Check for proper installation of aftermarket electronic equipment which may affect the integrity of other systems (Refer to Troubleshooting
Procedures). See: Diagrams/Diagnostic Aids
