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

Rear Window Defogger Inoperative Full

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. Connect a Scan Tool .
  2. Turn the ignition switch to the RUN position.
  3. Turn the rear defogger on.
  4. Display the SBM outputs.

Is the rear defogger being requested on?

--

Go to Step  3

Go to Step  11

3
  1. Turn the ignition switch to the RUN position.
  2. Disconnect the rear defogger relay.
  3. Connect a test lamp between the relay connector F3 and ground. Refer to Probing Electrical Connectors in Wiring Systems.

Does the test lamp light?

--

Go to Step  4

Go to Step  12

4

Connect the test lamp between the relay connector terminal A2 and ground. Refer to Probing Electrical Connectors in Wiring Systems.

Does the test lamp light?

--

Go to Step  5

Go to Step  13

5

Connect the test lamp between the relay connector terminal A2 and terminal B3. Refer to Probing Electrical Connectors in Wiring Systems.

Does the test lamp light?

--

Go to Step  13

Go to Step  6

6
  1. Disconnect the following rear defogger components:
    2. • The positive feed bus connector
    • The negative feed bus connector
  2. Connect a fused jumper between the relay connector terminal F3 and terminal A4.
  3. Connect the test lamp between the positive feed bus connector terminal A and ground?

Does the test lamp light?

--

Go to Step  7

Go to Step  9

7

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

Does the test lamp light?

--

Go to Step  8

Go to Step  10

8

Test the rear defogger ground circuit for an open.

Is there an open in the defogger ground CKT?

--

Go to Step  19

Go to Step  9

9

Test CKT 293 (PPL) for an open.

Is there an open in CKT 293?

--

Go to Step  19

Go to Step  10

10

Test for proper contact at the rear defogger connectors.

Is the terminal contact OK?

--

Go to Step  20

--

11

Test for the proper terminal contact at the SBM

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

Is the terminal contact OK?

--

Go to Body Control Module Replacement in Body Control System

Go to Step  20

12

Test CKT 241 (BRN) for an open.

Is there an open in CKT 241?

--

Go to Step  19

Go to Step  13

13

Test CKT 1042 (RED) for an open.

Is there an open in CKT 1042?

--

Go to Step  19

Go to Step  14

14

Connect the test lamp between the relay connector terminal F3 and terminal A4.

Does the test lamp light?

--

Go to Step  15

Go to Step  17

15
  1. Connect the rear defogger relay.
  2. Disconnect the SBM.
  3. Measure the voltage between terminal A3 and ground.

Is the voltage within the specified range?

10-15 V

Go to Step  16

Go to Step  18

16

Test CKT 193 (WHT) for an open or a short to ground.

Is there an open or a short to ground in CKT 193?

--

Go to Step  19

--

17

Test for an open or a short at the rear defogger relay terminals.

Are the terminals functioning?

--

Go to Step  20

--

18

Test for proper connector contact at the SBM.

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

Did you complete the repair?

--

Go to Defogger System Check

--

19

Repair an open or a short to ground in the faulty CKT. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Defogger System Check

--

20

Repair the faulty terminal contact. Refer to Connector Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Defogger System Check

--

Rear Window Defogger Inoperative Partially

Rear Defogger Grid Partially 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 RUN.
  2. Turn the rear defogger on.
  3. Wait 5 minutes.

Does the rear window feel warm?

--

Go to Step  3

Go to Step  4

3
  1. Connect a test lamp to ground.
  2. Lightly touch the test lamp lead to the middle of each grid line.

Does the test lamp glow dimly?

--

Go to Step  4

Go to Step  5

4
  1. Inspect the rear defogger connectors for proper contact.
  2. Repair the connectors as necessary. Refer to Connector Repairs in Wiring Systems.

Is the repair complete?

--

Go to Defogger System Check

--

5

Lightly move the test lamp along the open grid line from the power bus (right side) to the ground bus (left side).

You have located the open point when the test lamp goes out.

Is the repair complete?

--

Go to Defogger System Check

--