GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Did you perform the Defogger System Check?

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Go to Step 2

Go to Defogger System Check

2

  1. Disconnect the heater-A/C and rear defogger control assembly connector C1.
  2. Turn the ignition switch to the ON position.
  3. Connect a test light between the heater-A/C and rear defogger control assembly harness connector C1 terminal B and ground.

Did the test light illuminate?

--

Go to Step 3

Go to Step 4

3

Connect the test light between the heater-A/C and rear defogger control assembly harness connector C1 terminal H and B.

Did the test light illuminate?

--

Go to Step 5

Go to Step 6

4

Repair the open in CKT 41 between the fuse block and the heater-A/C and rear defogger control assembly. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Defogger System Check

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5

Connect the test light between the heater-A/C and rear defogger control assembly harness connector C1 terminal A and terminal H.

Did the test light illuminate?

--

Go to Step 7

Go to Step 8

6

Repair the open in CKT 150 between the heater-A/C and rear defogger control assembly and G204. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Defogger System Check

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7

  1. Reconnect the heater-A/C and rear defogger control assembly connector C1.
  2. Use the test light in order to backprobe the heater-A/C and rear defogger control assembly connector C1 between terminal D and ground.
  3. Turn the defogger switch to the ON position.

Did the test light illuminate?

--

Go to Step 9

Go to Step 10

8

Repair the open in CKT 1340 between the fuse block and the heater-A/C and rear defogger control assembly. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Defogger System Check

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9

  1. Disconnect the rear defogger grid connectors.
  2. Connect the test light between the rear defogger grid harness connector C1 and ground.

Did the test light illuminate?

--

Go to Step 11

Go to Step 12

10

Replace the heater-A/C and rear defogger control assembly.

Did you complete the repair?

--

Go to Defogger System Check

--

11

Connect the test light between the rear defogger grid harness connector C2 terminal A and B+.

Did the test light illuminate?

--

Go to Step 13

Go to Step 14

12

Repair the open in CKT 293 between the heater-A/C and rear defogger control assembly and the rear defogger grid. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Defogger System Check

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13

Repair the open in the rear defogger grid. Refer to Grid Line Repair .

Did you complete the repair?

--

Go to Defogger System Check

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14

Repair the open in CKT 250 between the rear defogger grid and G302. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Defogger System Check

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