DEFINITION: Testing the rear defogger grid lines for proper operation.

1. Turn ON the ignition, with the engine OFF.
2. Press the rear defogger button.

After five minutes, does the rear defogger feel warm?

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Go to Step 2

Go to Step 3

1. Repress the rear defogger button if timed out.
2. With a test lamp connected to a good ground and starting at the supply side, test each individual grid line across the grid until an open is located. (The test lamp will dim as you test across the grid and an open circuit is located when the test lamp goes out).

Was an open circuit located?

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Go to Grid Line Repair

Go to Step 4

Inspect for poor connections at the defogger grid. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Did you find and correct the condition?

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Go to Step 4

Go to Rear Window Defogger Inoperative

Operate the system in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 2