GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1999 🢒 Park Avenue 🢒 Body and Accessories 🢒 Doors 🢒 Rear Window Defogger Inoperative

Rear Window Defogger Inoperative Full

Step

Action

Value(s)

Yes

No

1
  1. Connect the Scan Tool .
  2. Turn the ignition to RUN.
  3. Turn the rear defogger ON.
  4. Display the SBM outputs.

Is the rear defogger being requested on?

--

Go to Step 2

Go to Step 10

2
  1. Turn the ignition switch to RUN.
  2. Disconnect the HTD BK Light Relay.
  3. Connect the test lamp between relay connector A2 and ground.

Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp light?

--

Go to Step 3

Go to Step 11

3

Connect the test lamp between relay connector terminal A2 and ground.

Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp light?

--

Go to Step 4

Go to Step 12

4

Connect the test lamp between relay connector terminal A2 and B3.

Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp light?

--

Go to Step 13

Go to Step 5

5
  1. Disconnect the following HTD BK Lite components:
    2. • Positive feed bus connector
    • Negative feed bus connector
  2. Connect a fused jumper between relay connector terminal A2 and B3. Refer to Using Fused Jumper Wires in Wiring Systems.
  3. Connect the test lamp between the positive feed bus connector terminal A and ground?

Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp light?

--

Go to Step 6

Go to Step 8

6

Connect the test lamp between the positive feed bus connector terminal A and the negative feed bus connector terminal B.

Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp light?

--

Go to Step 9

Go to Step 7

7

Test the rear defogger ground circuit for an open.

Refer to Testing for Continuity in Wiring Systems.

Was an open condition repaired?

--

System OK

--

8

Test CKT 293 (PPL) for an open.

Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Was an open condition repaired?

--

System OK

--

9

Test for proper terminal contact at the rear defogger connectors.

Refer to Intermittents and Poor Connections Diagnosis and Testing for Electrical Intermittents in Wiring Systems.

Was an open condition repaired?

--

System OK

--

10

Test for the proper terminal contact at the SBM

Refer to Intermittents and Poor Connections Diagnosis and Testing for Electrical Intermittents in Wiring Systems.

If the contact is good, replace the SBM.

Refer to Body Control Module Replacement in Body Control System.

Is the repair complete?

--

System OK

--

11

Test CKT 241 (BRN) for an open or short to ground.

Refer to Testing for Continuity or Testing for Short to Ground in Wiring Systems.

Was an open condition repaired?

--

System OK

--

12

Test CKT 1042 (RED) for an open or short to ground.

Refer to Testing for Continuity or Testing for Short to Ground in Wiring Systems.

Was an open condition repaired?

--

System OK

--

13
  1. Connect the test lamp between the relay connector terminal A2 and B3. Refer to Troubleshooting with a Test Lamp in Wiring Systems.
  2. Turn the Ignition switch to RUN.
  3. Disconnect the (SBM).

Does the test lamp light?

--

Go to Step 15

Go to Step 14

14
  1. Connect the HTD BK Lite Relay.
  2. Disconnect the SBM.
  3. Measure the voltage at terminal A3 and ground.

Refer to Measuring Voltage in Wiring Systems.

Is the voltage measured?

--

Go to Step 17

Go to Step 18

15

Repair CKT 193 (WHT) for a short to ground.

Is the repair complete?

--

System OK

--

16

Test for an open or a short at the HTD BK Lite Relay terminals.

Are the terminals functioning?

--

System OK

Go to Step 19

17

Test for proper connector contact at the SBM.

Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.

If the contact is good, replace the SBM. Refer to Body Control Module Replacement in Body Control System.

Is the repair complete?

--

System OK

--

18

Inspect CKT   193   (WHT) for an open.

Is an open condition present?

--

Go to Step 20

Go to Step 16

19

Replace the HTD BK Lite Relay.

Is the repair complete?

--

System OK

--

20

Repair the open in CKT   193   (WHT).

Refer to Wiring Repairs in Wiring Repairs

Is the repair complete?

--

System OK

--

Rear Window Defogger Inoperative Partially

Rear Defogger Grid Partially Inoperative

Step

Action

Value(s)

Yes

No

1
  1. Turn the ignition to RUN.
  2. Turn the rear defogger ON.
  3. Wait five minutes.

Does the rear window feel warm?

--

Go to Step 2

Go to Step 3

2
  1. Connect the test lamp to ground. Refer to Troubleshooting with a Test Lamp in Wiring Systems.
  2. Lightly touch the test lamp lead to the middle of each grid line.

Does the test lamp glow dimly?

--

Go to Step 3

Go to Step 4

3
  1. Check for the proper rear defogger connectors. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
  2. Repair the connectors as necessary.

Refer to Repairing Connector Terminals in Wiring Systems.

Is the repair complete?

--

System OK

--

4
    •  Lightly move the test lamp along the open grid line from power bus (right side) to ground bus (left side). Refer to Troubleshooting with a Test Lamp in Wiring Systems.
    • You have located the open point when the test lamp goes out. Refer to Grid Line Repair Grid Line Repair .

Is the repair complete?

--

System OK

--