GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1997 🢒 Catera 🢒 Body and Accessories 🢒 Stationary Windows 🢒 Rear Window Defogger Inoperative

Rear Window Defogger Inoperative Defog and Heated Mirrors Inop

Step

Action

Value(s)

Yes

No

1

Did you perform the Defogger and Heated Mirrors System Check?

--

Go to Step 2

Go to Defogger System Check

2
  1. Disconnect the heated outside rear view mirror and rear window defogger window relay K35 from the relay box.
  2. Turn the ignition switch to the ON position.
  3. Use the DMM to measure the voltage between terminal 2 of the relay box connector and a good ground.

Is the measured voltage within the specified value?

B+

Go to Step 4

Go to Step 3

3
  1. Remove and inspect fuse #34. If it is open, test the related circuitry for a possible short to ground. Repair as needed.
  2. If fuse #34 is OK, locate and repair an open circuit in circuit A18.

Is the repair complete?

--

Go to Step 11

--

4

Use the DMM to measure the voltage between terminal 1 of the relay box connector and a good ground.

Is the measured voltage within the specified value?

B+

Go to Step 6

Go to Step 5

5
  1. Locate an open or a high resistance in circuit X84.
  2. Repair the open or the high resistance in circuit X84.

Is the repair or complete?

--

Go to Step 11

--

6

Use the DMM to measure the resistance between terminal 6 of the relay box connector and a good ground.

Is the measured resistance less than the specified value?

5 ohms

Go to Step 8

Go to Step 7

7
  1. Locate an open or a high resistance in circuit F84.
  2. Repair the open or the high resistance in circuit F84.

Is the repair complete?

--

Go to Step 11

--

8
  1. Press the rear window defogger switch ON.
  2. Use the DMM to measure the voltage between terminal 4 of the relay box connector and a known good ground while pressing the switch.

Is the measured voltage within the specified range?

B+

Go to Step 10

Go to Step 9

9
  1. Locate an open or a high resistance in circui  FM14.
  2. Repair the open or the high resistance in circuit FM14.
  3. If circuit FM14 is OK, replace the heater and A/C control. Refer to Control Assembly Replacement in HVAC Systems.

Is the repair or replacement complete?

--

Go to Step 11

--

10

Replace the heated outside rear view mirror and rear window defogger window relay K35.

Is the replacement complete?

--

Go to Step 11

--

11
  1. Connect all connectors and components that were disconnected.
  2. Cycle the ignition switch from the OFF position to the ON position.
  3. Press the rear window defogger switch ON.

Does the rear window defogger and the heated mirrors operate properly?

--

System OK

Go to Step 1

Rear Window Defogger Inoperative No DTC Set

Step

Action

Value(s)

Yes

No

1

Did you perform the Defogger and Heated Mirrors System Check?

--

Go to Step 2

Go to Defogger System Check .

2
  1. Disconnect the radio antenna amplifier connector.
  2. Turn the ignition switch to the ON position.
  3. Press the rear window defogger switch ON.
  4. Use the DMM to measure the voltage between terminal X of the radio antenna amplifier connector and a good ground.

Is the measured voltage within the specified value?

B+

Go to Step 4

Go to Step 3

3
  1. Locate an open or a high resistance in circuits X15 and/or X16.
  2. Repair the open or the high resistance in circuit X15 and/or X16.
  3. If these circuits are OK, replace the heated outside rear view mirror and rear window defogger window relay K35.

Is the repair or replacement complete?

--

Go to Step 8

--

4
  1. Disconnect the connector at the rear window defogger grid.
  2. Use the DMM to measure the voltage between the two terminals.

Is the measured voltage within the specified value?

B+

Go to Step 6

Go to Step 5

5
  1. Locate an open or a high resistance in circuits X1 and/or X2.
  2. Repair the open or the high resistance in circuits X1 and/or X2.
  3. If these circuits are OK, replace the radio antenna amplifier. Refer to Antenna Amplifier Replacement in Entertainment.

Is the repair or replacement complete?

--

Go to Step 8

--

6
  1. Test the integrity of the rear window defogger grid.
  2. Repair the grid lines if necessary. Refer to Grid Line Repair .

Is the rear window defogger grid OK?

--

Go to Step 8

Go to Step 7

7

Repair or replace the rear window defogger grid. Refer to Grid Line Repair .

Is the repair or replacement complete?

--

Go to Step 8

--

8
  1. Connect all the connectors and components that were disconnected.
  2. Cycle the ignition switch from the OFF position to the ON position.
  3. Press the rear window defogger switch ON.

Does the rear window defogger operate properly?

--

System OK

Go to Step 1