Testing If Display Approx. - 40° C To - 46° C
-- Disconnect the MAF / IAT sensor -G70 / G42- electrical harness connector.
-- Switch ignition ON.
-- Using a jumper wire, connect the MAF / IAT sensor -G70 / G42- electrical harness connector terminals 3 to 4.
-- Check the value indicated on the scan tool display.
-- Switch ignition OFF.
If indication increased to approx. 140 °C:
-- Replace the MAF / IAT sensor -G70 / G42- Refer to the Repair Information.
If indication remains at approx. -40 °C or -46 °C:
Checking wiring
If the manufacturers test box is being used, perform the following step.
-- Install the test box.
If the manufacturers test box is not being used, perform the following step.
-- Remove the Engine Control Module (ECM) -J623-. Refer to the Repair Information.
-- Disconnect the ECM harness.
-- Using a multimeter, check the MAP / IAT sensor -G70 / G42- electrical harness connector terminal 3 to the Engine Control Module (ECM) -J623- electrical harness connector T94 terminal 13 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 4 of the MAF / 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 and the sensor resistance was OK:
-- Replace the Engine Control Module (ECM) -J623-. Refer to the Repair Information.