Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Relay Switch B+ Circuit | 2 | 2 | -- | -- |
Relay Coil B+ Circuit | 2 | 2 | -- | -- |
HVAC B+ Circuit | 2 | 2 | -- | -- |
Rear Defogger Relay Control | B0285 | B0286 | B0286 | -- |
Relay Controlled Output Circuit | 2 | 2 | 3 | -- |
Rear Defogger Switch Signal | 2 | 2 | 2 | -- |
Defog Switch Ground | -- | 1, 2 | 1, 2 | -- |
Rear Window Defogger Grid Ground | -- | 2 | 2 | -- |
1. HVAC Defogger Indicator Inoperative 2. Rear defogger Inoperative 3. Rear Defogger Always ON |
The body control module (BCM) monitors the voltage level on the supply voltage circuit of the REAR DEFOG relay. The voltage level should be low while the REAR DEFOG relay is de-energized. The voltage will be near system voltage when the BCM energizes the REAR DEFOG relay.
Battery voltage must be between 9-16 volts.
This DTC will set when the BCM detects a low voltage level in the supply circuit of the REAR DEFOG relay when the relay is energized.
This DTC will set when the BCM detects an open/high resistance in the supply circuit of the REAR DEFOG relay when the relay is energized.
• | The BCM stores the DTC to memory. |
• | The rear window defogger will not operate. |
• | This DTC will change from current to history when the fault is no longer present. |
• | A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present. |
• | The technician issues a scan tool CLEAR DTCs command. |
Window Systems Connector End Views
Rear Window Defogger Description and Operation
⇒ | If the reading does not change between the commanded states, refer to Rear Defogger Switch Malfunction in Circuit/System Testing |
⇒ | If the rear window defogger does not turn ON and OFF when changing between the commanded states, refer to Rear Defogger Malfunction in Circuit/System testing. |
⇒ | If the Defogger Indicator does not illuminate, replace the HVAC control module. |
⇒ | If not the specified value, test the signal circuit terminal 22 for a short to ground. If the circuit tests normal, replace the BCM. |
⇒ | If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM. |
⇒ | If greater than the specified range, test for an open/high resistance. |
⇒ | If the test lamp illuminates, test the control circuit for a short to voltage. |
⇒ | If the test lamp does not illuminate, test the switch side B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the switch side circuit fuse is open, test the switch side control circuit terminal for a short to ground. |
⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. |
⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. |
⇒ | If the resistance is not within the specified range, replace the relay. |
• | 30 and 86 |
• | 30 and 87 |
• | 30 and 85 |
• | 85 and 87 |
⇒ | If not the specified value, replace the relay. |
⇒ | If greater than the specified range, replace the relay. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for HVAC control module and BCM replacement, setup, and programming. |