GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 1999 🢒 Grand Prix 🢒 Body and Accessories 🢒 Stationary Windows 🢒 Rear Window Defogger Inoperative

Step

Action

Value(s)

Yes

No

1

Did you perform the Defogger System Check?

--

Go to Step 2

Go to Defogger System Check

2
  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 comes on.

Does the indicator turn on?

--

Go to Step 3

Go to Step 16

3
  1. Remove the rear window defogger relay.
  2. Use a test lamp to probe the rear window defogger relay harness connector between terminal A2 and terminal C1.

Does the test lamp light?

--

Go to Step 4

Go to Step 9

4

Use a test lamp to backprobe the rear window defogger relay harness connector between terminal C2 and ground.

Does the test lamp light?

--

Go to Step 5

Go to Step 8

5
  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 lamp to backprobe the rear window defogger relay harness connector between terminal A1 and terminal C2.

Does the test lamp light?

--

Go to Step 6

Go to Step 7

6

Replace the Rear Window Defogger Relay

Is the repair complete?

--

Go to Defogger System Check

--

7
  1. Repair a poor connection or an open in circuit 193 (WHT).
  2. Inspect the system again.

Is the repair complete?

--

Go to Defogger System Check

--

8
  1. Repair a poor connection or an open in circuit 541 (BRN) between the rear window defogger relay harness connector terminal C2 and the fuse block terminal B2.
  2. Inspect the system again.

Is the repair complete?

--

Go to Defogger System Check

--

9
  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 lamp to backprobe the rear window defogger relay harness connector between terminal C1 and ground.

Does the test lamp light?

--

Go to Step 10

Go to Step 15

10
  1. Reinstall the rear window defogger relay.
  2. If the rear defogger ON indicator turns off before the test is made, press and release the rear defogger switch again.
  3. Use a test lamp to probe between the rear defogger grid harness connector C1 and connector C2.

Does the test lamp light?

--

Go to Step 11

Go to Step 12

11

Repair the rear defogger grid. Refer to Rear Window Defogger Braided Lead Wire .

Is the repair complete?

--

Go to Defogger System Check

--

12
  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 lamp to probe between the rear defogger grid harness connector C1 and ground.

Does the test lamp light?

--

Go to Step 13

Go to Step 14

13
  1. Repair a poor connection or an open in circuit 750 (BLK) between the rear defogger grid connector C2 and G301.
  2. Inspect the system again.

Is the repair complete?

--

Go to Defogger System Check

--

14
  1. Repair a poor connection or an open in circuit 293 (PPL) between the rear window defogger relay connector terminal A2 and the rear defogger grid connector grid connector C1.
  2. Inspect the system again.

Is the repair complete?

--

Go to Defogger System Check

--

15
  1. Repair a poor connection or an open in circuit 1040 (ORN) between the fuse block terminal G2 and the rear window defogger relay harness connector terminal C1.
  2. Inspect the system again.

Is the repair complete?

--

Go to Defogger System Check

--

16

Inspect to see if the DIC/HVAC fuse (fuse 4) in the fuse block is open.

Is the fuse open?

--

Go to Step 17

Go to Step 18

17
  1. Repair the short to ground in circuit 541 (BRN).
  2. Inspect the system again.

Is the repair complete?

--

Go to Defogger System Check

--

18
  1. Turn the ignition switch to the RUN position.
  2. Use a test lamp to backprobe the heater-a/c control between connector terminal C1 and terminal C5 (CJ2) or between connector C2 terminal C and terminal K (C60).

Does the test lamp light?

--

Go to Step 19

Go to Step 21

19
  1. Press and release the rear defogger switch.
  2. Use a test lamp to backprobe between the heater-a/c control harness connector terminal D15 (CJ2) or between connector C2 terminal D (C60) and ground.

Does the test lamp light?

--

Go to Step 20

Go to Step 24

20
  1. Repair a short to B+ in circuit 193 (WHT).
  2. Inspect the system again.

Is the repair complete?

--

Go to Defogger System Check

--

21

Use a test lamp to backprobe between the heater-a/c control harness connector terminal C5 (CJ2) or between connector C2 terminal C (C60) and ground.

Does the test lamp light?

--

Go to Step 22

Go to Step 23

22
  1. Repair a poor connection or an open in circuit 150 (BLK) between the heater and A/C control harness connector terminal C1 (CJ2) or between connector C2 terminal K (C60) and G205.
  2. Inspect the system again.

Is the repair complete?

--

Go to Defogger System Check

--

23
  1. Repair a poor connection or an open in circuit 541 (BRN) between the fuse block terminal B2 and the heater and A/C control harness connector terminal C5 (CJ2) or between connector C2 terminal C (C60) and ground.
  2. Inspect the system again.

Is the repair complete?

--

Go to Defogger System Check

--

24

Replace the Heater A/C Control. Refer to the following procedures:

    •  Control Assembly Replacement for Manual HVAC Systems
    •  Control Assembly Replacement for Automatic HVAC Systems

Is the repair complete?

--

Go to Defogger System Check

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