1

1. Turn the ignition switch to the ON position.
2. Install the scan tool.
3. Monitor HVAC data, rear defog Zone 1 and 2.

Does either zone indicate on?

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Go to Step 2

Go to Step 3

1. Turn the ignition OFF.
2. Disconnect the HVAC control assembly connector.
3. Turn the ignition ON.

Does the scan tool indicate rear defog Zone 1 or 2 on?

--

Go to Step 6

Go to Step 10

1. Turn the ignition switch to the ON position.
2. Remove the appropriate rear defog relay.
3. Connect a test lamp between B+ and terminal B3 (relay 1) or B7 (relay 2)

Does the test lamp light?

--

Go to Step 4

Go to Step 7

1. Turn the ignition switch to the OFF position.
2. Disconnect HVAC programmer connector C2
3. Turn the ignition ON.
4. Connect a test lamp between B+ and terminal B3 (relay 1) or B7 (relay 2)

Does the test lamp light?

--

Go to Step 5

Go to Step 6

Repair the short to ground in circuit 1777 (RED) or circuit 193 (WHT).

Has the repair been made and the system rechecked?

--

Go to Defogger System Check

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Replace the HVAC programmer. Refer to Programmer Replacement in HVAC.

Has the repair been made and the system rechecked?

--

Go to Defogger System Check

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1. Turn the ignition switch to the OFF position.
2. Connect a test lamp between ground and terminal B1 (relay 1) or B5 (relay 2)

Does the test lamp light?

--

Go to Step 8

Go to Step 9

Repair a short to voltage in circuit 293 (PPL) relay 2.

Has the repair been made and the system rechecked?

--

Go to Defogger System Check

--

Replace the suspect relay.

Has the repair been made and the system rechecked?

--

Go to Defogger System Check

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Replace the HVAC control assembly. Refer to Control Assembly Replacement - Passenger in HVAC.

Has the repair been made and the system rechecked?

--

Go to Defogger System Check

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