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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Corvette 🢒 Body and Accessories 🢒 Body Control System 🢒 Defogger Inoperative - Rear Window, Indicator Lamp On

Defogger Inoperative - Rear Window, Indicator Lamp On Defogger/Htd. Mirrors Inop-CJ2

Defogger Inop-Rear Window, Indicator Lamp On (Defogger/Htd. Mirrors Inop-CJ2)

Step

Action

Value(s)

Yes

No

DEFINITION: Both the rear defogger grid and the outside heated rearview mirrors are not operating when the rear defogger button is depressed. DTCs B0432, B0433, U1255 by the BCM or U1153 by the Instrument Panel Cluster (IPC) has not been set.

1

Where you sent here from the Defogger System Check?

--

Go to Step 2

Go to Defogger System Check

2
  1. Start engine and allow to idle in Park.
  2. Depress the rear defogger switch.

Does the rear window defogger indicator illuminate?

--

Go to Step 3

Go to Step 4

3
  1. Turn the ignition switch to the OFF position.
  2. Install the scan tool and set it to read switch inputs.
  3. Start engine and allow to idle in Park.
  4. Depress the rear defogger switch to the ON position.
  5. Depress the rear defogger switch to the OFF position.

Does the scan tool display show the rear defogger switch input toggling ON and then OFF?

--

Go to Step 5

Go to Step 4

4

Replace the HVAC control head. Refer to Control Assembly Replacement .

Is the repair complete?

--

Go to Defogger System Check

--

5

Replace the BCM. Refer to Body Control Module Replacement .

Is the repair complete?

--

Go to Defogger System Check

--

Defogger Inoperative - Rear Window, Indicator Lamp On Defogger/Htd. Mirrors Inop-C60

Defogger Inop-Rear Window, Indicator Lamp On (Defogger/Heated mirrors inop-C60)

Step

Action

Value(s)

Yes

No

DEFINITION: Both the rear defogger grid and the outside heated rearview mirrors are not operating when the rear defogger button is depressed. DTCs B0432, B0433, U1255 by the BCM or U1153 by the Instrument Panel Cluster (IPC) has not been set.

1

Where you sent here from the Defogger System Check?

--

Go to Step 2

Go to Defogger System Check

2
  1. Start engine and allow to idle in Park.
  2. Depress the rear defogger switch.

Does the rear window defogger indicator illuminate?

--

Go to Step 3

Go to Step 5

3
  1. Turn the ignition switch to the OFF position.
  2. Disconnect the HVAC control head connector C1.
  3. Using a DMM, measure for continuity between the HVAC control head connector C1 terminal D and the BCM connector C2 terminal C10.

Is CKT 681 continuous between these two connectors?

--

Go to Step 6

Go to Step 4

4

Repair the open in CKT 681.

Is the repair complete?

--

Go to Defogger System Check

--

5

Replace the HVAC control head. Refer to Control Assembly Replacement .

Is the repair complete?

--

Go to Defogger System Check

--

6

Replace the BCM. Refer to Body Control Module Replacement .

Is the repair complete?

--

Go to Defogger System Check

--

Defogger Inoperative - Rear Window, Indicator Lamp On Htd. Mirrors Work Normally-CJ2

Defogger Inop-Rear Window, Indicator Lamp On (Htd. Mirrors Work normally-CJ2)

Step

Action

Value(s)

Yes

No

DEFINITION: Only the rear defogger grid is inoperative, the outside heated rearview mirrors are operating when the rear defogger button is depressed. DTCs B0432, B0433, U1255 by the BCM or U1153 by the Instrument Panel Cluster (IPC) has not been set.

1

Where you sent here from the Defogger System Check?

--

Go to Step 2

Go to Defogger System Check

2

Are all of the rear window defogger grid lines inoperative?

--

Go to Step 3

Go to Grid Line Repair

3

Inspect the RR DEFOG Maxifuse® #46.

Is the fuse open?

--

Go to Step 4

Go to Step 7

4
  1. Remove the RR DEFOG Mini Relay #44 in the instrument panel electrical center.
  2. Using a DMM, measure for continuity across the switch portion of the relay from terminal 3 to terminal 5 (or terminal 30 to terminal 87).

Is continuity present across the switch portion of the RR DEFOG Mini Relay #44?

--

Go to Step 13

Go to Step 5

5
  1. Disconnect the rear window defogger grid connector on the battery side leading toward the RR DEFOG Mini Relay #44.
  2. RR DEFOG Mini Relay #44 is still removed.
  3. Using a DMM, measure for continuity between the rear window defogger grid connector (battery side) terminal A and ground.

Is CKT 293 continuous to ground?

--

Go to Step 6

Go to BCM DTC B0432

6

Repair a short to ground in CKT 293.

Is the repair complete?

--

Go to Defogger System Check

--

7
  1. Disconnect the RR DEFOG Mini Relay #44 from the instrument panel electrical center.
  2. Disconnect the rear window defogger grid connector on the battery side leading toward the RR DEFOG Mini Relay #44.
  3. Using a DMM, measure CKT 293 for continuity between the rear window defogger grid connector (battery side) terminal A and the CKT 293 terminal inside the instrument panel electrical center which is used for the RR DEFOG Mini Relay #44.

Is CKT 293 continuous between these two points?

--

Go to Step 9

Go to Step 8

8

Repair an open or high resistance in CKT 293.

Is the repair complete?

--

Go to Defogger System Check

--

9
  1. Disconnect the rear window defogger grid connector on the ground side leading toward G301.
  2. Using a DMM, measure for continuity between the rear window defogger grid connector (ground side) terminal A and ground.

Is continuity present in CKT 350 between the rear window defogger grid connector and G301?

--

Go to Step 11

Go to Step 10

10

Repair an open or high resistance in CKT 350.

Is the repair complete?

--

Go to Defogger System Check

--

11
  1. Disconnect the body control module (BCM) connector C2.
  2. Reinstall the RR DEFOG Mini Relay #44 into the instrument panel electrical center.
  3. Connect a fused jumper between the BCM connector C2 terminal C3 and ground.
  4. Turn the ignition switch to the ON position.
  5. Using a DMM, measure the voltage between the rear window defogger grid connector (battery side) terminal A and ground.

Is the voltage within the specified values?

10.0-14.0V

Go to Step 12

Go to Step 13

12

Replace the BCM. Refer to Body Control Module Replacement .

Is the repair complete?

--

Go to Defogger System Check

--

13

Replace the RR DEFOG Mini Relay #44.

Is the repair complete?

--

Go to Defogger System Check

--

Defogger Inoperative - Rear Window, Indicator Lamp On Htd. Mirrors Work Normally-C60

Defogger Inop-Rear Window, Indicator Lamp On (Heated Mirrors Work Normally-C60)

Step

Action

Value(s)

Yes

No

DEFINITION: Only the rear defogger grid is inoperative, the outside heated rearview mirrors are operating when the rear defogger button is depressed. DTCs B0432, B0433, U1255 by the BCM or U1153 by the Instrument Panel Cluster (IPC) has not been set.

1

Where you sent here from the Defogger System Check?

--

Go to Step 2

Go to Defogger System Check

2

Are all of the rear window defogger grid lines inoperative?

--

Go to Step 3

Go to Grid Line Repair

3

Inspect the RR DEFOG Maxifuse® #46.

Is the fuse open?

--

Go to Step 4

Go to Step 7

4
  1. Remove the RR DEFOG Mini Relay #44 in the instrument panel electrical center.
  2. Using a DMM, measure for continuity across the switch portion of the relay from terminal 3 to terminal 5 (or terminal 30 to terminal 87).

Is continuity present across the switch portion of the RR DEFOG Mini Relay #44?

--

Go to Step 17

Go to Step 5

5
  1. Disconnect the rear window defogger grid connector on the battery side leading toward the RR DEFOG Mini Relay #44.
  2. RR DEFOG Mini Relay #44 still removed.
  3. Using a DMM, measure for continuity between the rear window defogger grid connector (battery side) terminal A and ground.

Is CKT 293 continuous to ground?

--

Go to Step 6

Go to BCM DTC B0432

6

Repair a short to ground in CKT 293.

Is the repair complete?

--

Go to Defogger System Check

--

7
  1. Disconnect the RR DEFOG Mini Relay #44 from the instrument panel electrical center.
  2. Disconnect the rear window defogger grid connector on the battery side leading toward the RR DEFOG Mini Relay #44.
  3. Using a DMM, measure CKT 293 for continuity between the rear window defogger grid connector (battery side) terminal A and the CKT 293 terminal inside the instrument panel electrical center which is used for the RR DEFOG Mini Relay #44.

Is CKT 293 continuous between these two points?

--

Go to Step 9

Go to Step 8

8

Repair an open or high resistance in CKT 293.

Is the repair complete?

--

Go to Defogger System Check

9
  1. Disconnect the rear window defogger grid connector on the ground side leading toward G301.
  2. Using a DMM, measure for continuity between the rear window defogger grid connector (ground side) terminal A and ground.

Is continuity present in CKT 350 between the rear window defogger grid connector and G301?

--

Go to Step 11

Go to Step 10

10

Repair an open or high resistance in CKT 350.

Is the repair complete?

--

Go to Defogger System Check

--

11
  1. Disconnect the body control module (BCM) connector C2.
  2. Reinstall the RR DEFOG Mini Relay #44 into the instrument panel electrical center.
  3. Connect a fused jumper between the BCM connector C2 terminal C3 and ground.
  4. Turn the ignition switch to the ON position.
  5. Using a DMM, measure the voltage between the rear window defogger grid connector (battery side) terminal A and ground.

Is the voltage within the specified values?

10.0-14.0V

Go to Step 12

Go to Step 17

12
  1. Turn the ignition switch to the ON position.
  2. Depress the rear window defogger switch.

Does the defogger ON indicator light illuminate?

--

Go to Step 14

Go to Step 13

13

Replace the HVAC control head. Refer to Control Assembly Replacement .

Is the repair complete?

--

Go to Defogger System Check

--

14
  1. Turn the ignition switch to OFF.
  2. Disconnect the HVAC control head connector C1.
  3. Using a DMM, measure for continuity between the HVAC control head connector C1 terminal D and the BCM connector C2 terminal C10.

Is the CKT 681 continuous between these two connectors?

--

Go to Step 16

Go to Step 15

15

Repair an open or high resistance in CKT 681.

Is the repair complete?

--

Go to Defogger System Check

--

16

Replace the BCM. Refer to Body Control Module Replacement .

Is the repair complete?

--

Go to Defogger System Check

--

17

Replace the RR DEFOG Mini Relay #44.

Is the repair complete?

--

Go to Defogger System Check

--