GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 1999 🢒 Eighty Eight 🢒 Body and Accessories 🢒 Stationary Windows 🢒 Rear Window Defogger Inoperative

Rear Window Defogger Inoperative Buick/Oldsmobile

Step

Action

Value(s)

Yes

No

1
  1. Turn the ignition to the RUN position.
  2. Disconnect the rear defogger relay.
  3. Connect a test lamp between relay terminal 86 and ground.

Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp light?

--

Go to Step 2

Go to Step 9

2

Connect a test lamp between relay terminal 30 and ground.

Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp light?

--

Go to Step 3

Go to Step 10

3

Connect a test lamp between terminal 30 and terminal 87 of the relay.

Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp light?

--

Go to Step 11

Go to Step 4

4
  1. Disconnect the rear defogger positive and negative feed bus connector.
  2. Connect a jumper between terminal 30 and terminal 87 of the relay. Refer to Using Fused Jumper Wires in Wiring Systems.
  3. Connect a test lamp between the positive feed bus connector and the ground.

Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp light?

--

Go to Step 5

Go to Step 7

5

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

Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp light?

--

Go to Step 8

Go to Step 6

6
  1. Inspect CKT 1250 (BLK) for an open.
  2. Inspect connector C340 for proper contact.
  3. Repair the open, as necessary.

Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

System OK

--

7
  1. Inspect CKT 293 (PPL) for an open.
  2. Repair the open, as necessary.

Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

System OK

--

8
  1. Inspect the rear defogger connectors for proper contact.
  2. Repair the contact, as necessary.

Refer to Connector Repairs or Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

System OK

--

9
  1. Inspect CKT 1141 (BRN) for an open.
  2. Repair the open, as necessary.

Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

System OK

--

10
  1. Inspect CKT 1140 (ORN) for an open.
  2. Repair the open, as necessary.

Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

System OK

--

11
  1. Connect a test lamp between terminal 86 and terminal 85.
  2. Turn the rear defogger ON.

Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp light?

--

Go to Step 15

Go to Step 12

12
  1. Connect the rear defogger relay.
  2. Disconnect the connector to the heater and A/C programmer.
  3. Connect a test lamp between terminal A (C61 and C67), terminal D5 (C68), or F5 (CJ2) and ground.

Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp light?

--

Go to Step 13

Go to Step 17

13
  1. Inspect the heater and A/C programmer for the proper terminal contact.
  2. Repair the contact, as necessary.

Refer to Repairing Connector Terminals in Wiring Systems

Did you find and correct the condition?

--

System OK

Go to Step 14

14

Replace the heater and A/C programmer. Refer to Programmer Replacement .

Did you find and correct the condition?

--

System OK

--

15
  1. Inspect the terminals at the rear defogger relay.
  2. Repair the terminals, as necessary.

Refer to Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

System OK

Go to Step 16

16

Replace the rear defogger relay.

Did you find and correct the condition?

--

System OK

--

17
  1. Inspect CKT 193 (WHT) for an open.
  2. Repair the open, as necessary.

Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

System OK

--

Rear Window Defogger Inoperative Pontiac

Step

Action

Value(s)

Yes

No

1
  1. Turn the ignition to the RUN position.
  2. Disconnect connector C1 and connector C2 from the heater and A/C control.
  3. Connect a test lamp between connector C2 terminal H and ground.

Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp light?

--

Go to Step 2

Go to Step 8

2

Connect a test lamp between connector C1 terminal C and ground.

Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp light?

--

Go to Step 3

Go to Step 9

3

Connect a test lamp between terminal H and terminal F of connector C2.

Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp light?

--

Go to Step 4

Go to Step 10

4

Connect a test lamp between terminal C and terminal D of connector C1.

Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp light?

--

Go to Step 11

Go to Step 5

5
  1. Disconnect the positive feed bus connector of the rear defogger.
  2. Disconnect the negative feed bus connector of the rear defogger.
  3. Connect a fused jumper between terminal C and terminal D of connector C1. Refer to Using Fused Jumper Wires in Wiring Systems.
  4. Connect a 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 13

6

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

Refer to Troubleshooting with a Test Lamp in Wiring Systems

Does the test lamp light?

--

Go to Step 14

Go to Step 7

7
  1. Inspect CKT 1250 (BLK) for an open.
  2. Inspect connector C340 for proper contact. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
  3. Repair the condition, as necessary.

Refer to Wiring Repairs or Connector Repairs or Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

System OK

--

8
  1. Inspect CKT 41 (BRN) for an open.
  2. Inspect connector C200 terminal G1 for proper contact. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
  3. Repair the condition, as necessary.

Refer to Wiring Repairs or Connector Repairs or Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

System OK

--

9
  1. Inspect CKT 1140 (ORN) for an open.
  2. Repair the open, as necessary.

Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

System OK

--

10
  1. Inspect CKT 1250 (BLK) for an open.
  2. Repair the open as necessary.

Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

System OK

--

11
  1. Inspect for proper contact at the heater and A/C control assembly. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
  2. Repair the contact, as necessary.

Refer to Repairing Connector Terminals or Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

System OK

Go to Step 12

12

Replace the heater and A/C control assembly. Refer to Control Assembly Replacement

Did you find and correct the condition?

--

System OK

--

13
  1. Inspect CKT 293 (PPL) for an open.
  2. Repair the open, as necessary.

Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

System OK

--

14
  1. Inspect for proper terminal contact at the rear defogger. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
  2. Repair the rear defogger terminal connectors.

Refer to Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

System OK

--