Testing if display approx. - 40°C to - 46°C:

-- Disconnect the IAT sensor - G42- electrical harness connector.

-- Using a jumper wire, connect the IAT sensor - G42- electrical harness connector terminals 1 to 2.

-- Turn the ignition switch ON

-- Check the value indicated on the scan tool display.

If indication jumps to approx. 140°C: 

-- Switch ignition OFF.

-- Replace the IAT sensor - G42-. Refer to the Repair Information.

If indication remains at approx. - 40°C or - 46°C: 

Checking wiring 

-- Remove the Engine Control Module (ECM) -J623-. Refer to the Repair Information.

-- Disconnect the ECM harness.

-- Using a multimeter, check the IAT sensor - G42- electrical harness connector terminal 1 to the Engine Control Module (ECM) -J623- electrical harness connector T60 terminal 42 for an open circuit or a short to voltage, refer to the wiring diagram.

Specified values: Circuit continuity; 1.5 Ω max; Circuit voltage = 0 volts when disconnected from ECM (with ignition on).

If the specified value was Not obtained: 

-- Check the wiring for an open, high resistance or short circuit to Battery (+)

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

-- If necessary, repair the faulty wiring connection.

If the specified value was obtained: 

-- Using a multimeter, check terminal 2 of the IAT sensor to engine ground.

Specified value: 1.5 Ω Max

If the specified value was Not obtained: 

-- Check the wiring for an open circuit or high resistance.

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

-- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the ground circuit: 

-- Replace the Engine Control Module (ECM) -J623-. Refer to the Repair Information.