1. Turn OFF the ignition.
2. Disconnect the coolant temperature sensor connector from the automatic temperature control (FATC) harness.
3. Examine the wiring from the sensor to the connector and examine the connector for any signs of damage.
4. Measure the resistance between the coolant temperature sensor connector terminals.

Is there any sign of damage in the wiring or connector, or is the resistance outside the specified value at 20-25°C (68-77°F)?

2600-2100 ohms

Go to Step 2

Go to Step 3

Repair the damaged wiring or the connector, or replace the coolant temperature sensor as required.

Did you complete the repair?

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System OK

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1. Turn ON the ignition.
2. Measure the voltage between the 2 coolant temperature sensor connector terminals on the FATC harness.

Does the voltage measure less than or equal to the specified value?

4 V

Go to Step 7

Go to Step 4

Inspect the terminals on the coolant temperature sensor connector.

Is any problem found with the connector?

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Go to Step 5

Go to Step 6

Repair the connector terminals or replace the coolant temperature sensor or FATC controller as required.

Did you complete the repair?

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System OK

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1. Reconnect the coolant temperature sensor to the connector.
2. Turn ON the ignition.
3. Observe the temperature display on the screen controller.

Does this display indicate the continuing presence of a code 3 condition?

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Go to Step 9

System OK

1. Pull the FATC controller from the instrument panel, leaving the wiring harness connected.
2. Measure the voltage between terminals B12 and A4 by backprobing the connectors.

Does the voltage measure less than or equal to the specified value?

4 V

Go to Step 8

Go to Step 9

Replace the FATC controller.

Did you complete the repair?

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System OK

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1. Trace the wiring for coolant temperature sensor from the FATC controller to the coolant temperature sensor connector.
2. Repair any open or high resistance found in the wiring or connector terminals.

Did you complete the repair?

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System OK

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