GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1998 🢒 Regal 🢒 Body and Accessories 🢒 Stationary Windows 🢒 Rear Window Defogger Inoperative

Step

Action

Value(s)

Yes

No

1
  1. Turn the ignition switch to the RUN position.
  2. Press and release the rear defogger switch.
  3. Inspect to see if the defogger ON indicator turns on.

Does the defogger ON indicator turn on?

--

Go to Step 2

Go to Step 22

2
  1. Keep the ignition switch in the RUN position.
  2. Press and release the rear defogger switch.
  3. Inspect to see if the following defoggers turn on:
    4. • The rear window defogger
    • The right side outside rearview mirror defogger
    • The left side outside rearview mirror defogger

Do any defoggers turn on?

--

Go to Step 3

Go to Step 11

3

Do all of the defoggers turn on?

--

Go to Step 13

Go to Step 4

4

Does the rear window defogger turn on?

--

Go to Step 5

Go to Step 6

5

Did either the left or right sideview mirror defogger turn on?

--

Go to Step 30

Go to Step 35

6
  1. If the rear defogger ON indicator turns off before the test is made, press and release the rear defogger switch again.
  2. Use a test light to backprobe between the rear defogger grid harness connector C1 terminal A (circuit 293) and connector C2 terminal A (circuit 450).

Does the test light illuminate?

--

Go to Step 7

Go to Step 8

7

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

Is the repair complete?

--

System OK

--

8
  1. If the rear defogger ON indicator turns off before the test is made, press and release the rear defogger switch again.
  2. Use a test light to backprobe between the rear defogger grid harness connector C1 terminal A (circuit 293) and ground.

Does the test light illuminate?

--

Go to Step 9

Go to Step 10

9

Repair a poor connection or an open in circuit 450 (BLK) between the rear defogger grid connector C2 terminal A and G401.

Is the repair complete?

--

System OK

--

10

Repair a poor connection or an open in circuit 293 (PPL) between S268 and the rear defogger grid connector C1 terminal A.

Is the repair complete?

--

System OK

--

11
  1. If the rear defogger ON indicator turns off before the test is made, press and release the rear defogger switch again.
  2. Use a test light to backprobe the rear window defogger relay harness connector between terminal C1 (circuit 1040) and terminal A 2 (circuit 293).

Does the test light illuminate?

--

Go to Step 12

Go to Step 17

12

Use a test light to backprobe the rear window defogger relay harness connector between terminal C2 (circuit 41) and ground.

Does the test light illuminate?

--

Go to Step 13

Go to Step 16

13
  1. If the rear defogger ON indicator turns off before the test is made, press and release the rear defogger switch again.
  2. Use a test light to backprobe the rear window defogger relay harness connector between terminal C2 (circuit 41) and terminal A1 (circuit 193).

Does the test light illuminate?

--

Go to Step 14

Go to Step 15

14
  1. Replace the heater-a/c control. Refer to Control Assembly Replacement for the manual HVAC system or;
  2. Refer to Control Assembly Replacement for the Automatic HVAC system.

Is the repair complete?

--

System OK

--

15

Repair a poor connection or an open in circuit 193 (WHT).

Is the repair complete?

--

System OK

--

16

Repair a poor connection or an open in circuit  41 between S233 and the rear window defogger relay harness connector terminal C2.

Is the repair complete?

--

System OK

--

17
  1. If the rear defogger ON indicator turns off before the test is made, press and release the rear defogger switch again.
  2. Use a test light to backprobe the rear window defogger relay harness connector between terminal C1 (circuit 1040) and ground.

Does the test light illuminate?

--

Go to Step 18

Go to Step 19

18

Repair a poor connection or an open in circuit 293 (PPL) between the rear window defogger relay harness connector terminal A2 and S268.

Is the repair complete?

--

System OK

--

19

Use a test light to backprobe between B+ and the rear window defogger relay harness connector terminal C1 (circuit 1040).

Does the test light illuminate?

--

Go to Step 20

Go to Step 21

20

Repair the short to ground in circuit 1040(ORN).

Is the repair complete?

--

System OK

--

21

Repair a poor connection or an open in circuit 1040 (ORN).

Is the repair complete?

--

System OK

--

22

Check the HVAC fuse in the fuse block.

Is the HVAC fuse in the fuse block open?

--

Go to Step 23

Go to Step 24

23

Locate and Repair the short to ground in circuit 41 (BRN).

Is the repair complete?

--

System OK

--

24
  1. Turn the ignition switch to the RUN position.
  2. Use a test light to backprobe the heater-A/C control between the following electrical components:
    3. • (C60, CJ3) The harness connector C2 terminal C (circuit 41) and terminal K (circuit 1450)
    • (CJ2) The harness connector terminal C5 (circuit 41) and terminal C1 (circuit 1450)

Does the test light illuminate?

--

Go to Step 25

Go to Step 27

25
  1. Press and release the rear defogger switch.
  2. Use a test light to backprobe between the following electrical components:
    3. • (C60, CJ3) The heater-A/C control harness connector C2 terminal D (circuit 193) and ground
    • (CJ2) The heater-A/C control harness connector terminal D15 (circuit 193) and ground

Does the test light illuminate?

--

Go to Step 26

Go to Step 14

26

Repair a short to B+ in circuit 193 (WHT).

Is the repair complete?

--

System OK

--

27

Use a test light to backprobe between the following electrical components:

    • (C60, CJ3) The heater-A/C control harness connector C2 terminal C (circuit 41) and ground
    • (CJ2) The heater-A/C control harness connector terminal C5 (circuit 41) and ground

Does the test light illuminate?

--

Go to Step 28

Go to Step 29

28

Repair a poor connection or an open in circuit 1450 (BLK) between the following electrical components:

    • (C60, CJ3) The heater-A/C control harness connector C2 terminal K and G200
    • (CJ2) The heater-A/C control harness connector C2 and G200

Is the repair complete?

--

System OK

--

29

Repair a poor connection or an open in circuit 41 (BRN) between the fuse block terminal B4 and the following electrical components:

    • (C60, CJ3) The heater-A/C control harness connector C2 terminal C
    • (CJ2) The heater-A/C control harness connector terminal C5

Is the repair complete?

--

System OK

--

30
  1. If the rear defogger ON indicator turns off before the test is completed, press and release the rear defogger switch again.
  2. Use a test light to backprobe the inoperative outside rearview mirror harness connector between terminal D (circuit 267) and terminal E (circuit 750).

Is the test light on?

--

Go to Step 31

Go to Step 32

31

Replace the inoperative outside rearview mirror. Refer to Power Mirror Replacement .

Is the repair complete?

--

System OK

--

32
  1. If the rear defogger ON indicator turns off before the test is completed, press and release the rear defogger switch again.
  2. Use a test light to backprobe the inoperative outside rearview mirror harness connector between terminal D (circuit 267) and ground.

Is the test light on?

--

Go to Step 33

Go to Step 34

33

Repair a poor connection or an open in circuit 750 (BLK) between the inoperative sideview mirror harness connector terminal E and S303.

--

System OK

--

34

Repair a poor connection or an open in circuit 267 (ORN) between connector C200 terminal G2 and the inoperative outside rearview mirror harness connector terminal D.

Is the repair comlete?

--

System OK

--

35

Inspect the Heated Mirror fuse in the fuse block to see if it is open.

Is the fuse open?

--

Go to Step 36

Go to Step 37

36

Repair a short to ground in circuit 267 (ORN).

Is the repair complete?

--

System OK

--

37

Repair a poor connection or an open in circuit 293 (PPL) between the fuse block and S268.

Is the repair complete?

--

System OK

--