1. Place the ignition switch in the run position.
2. Disconnect the rear defogger relay.
3. Connect a test lamp between the following terminals and ground:

•	Terminal 86

•	Terminal 87

Does the test lamp illuminate at both terminals?

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Go to Step 2

Go to Step 3

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

Does the test lamp illuminate?

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Go to Step 4

Go to Step 7

Repair an open in CKT 41 or in CKT 1340. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

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System OK

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Connect a test lamp between terminal 30 and terminal 85 of the rear defogger relay connector.

Does the test lamp illuminate?

--

Go to Step 5

Go to Step 9

1. Backprobe the rear defogger switch connector terminal A (Buick/Oldsmobile) or terminal 2 (Pontiac) and ground.
2. Press the rear defogger switch.

Does the test lamp illuminate?

--

Go to Step 6

Go to Step 10

Test CKT 292 and CKT 681 for an open.

Is an open in CKT 292 or in CKT 681?

--

Go to Step 12

Go to Step 11

Test for an open in CKT 293 and in CKT 150.

Is an open in CKT 293 or in CKT 150?

--

Go to Step 12

Go to Step 13

Test for an open in CKT 293 or in the rear defogger grid.

Is an open in CKT 293 or in the rear defogger grid?

--

Go to Step 12

Go to Step 14

Test for an open in CKT 681.

Is an open in CKT 681?

--

Go to Step 12

Go to Step 11

Test for an open in CKT 39.

Is an open in CKT 39?

--

Go to Step 12

Go to Step 14

Replace the multi-function alarm module. Refer to Multifunction Alarm Module Replacement in Keyless Entry.

Did you complete the repair?

--

System OK

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Repair the open in the faulty CKT. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

System OK

--

Did you complete the repair?

--

System OK

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Replace the rear defogger switch. Refer to Rear Window Defogger Switch Replacement .

Did you complete the repair?

--

System OK

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