6-36 FI SYSTEM/ CVT SYSTEM
“C21” IAT SENSOR CIRCUIT MALFUNCTION
INSPECTION
DETECTED CONDITION POSSIBLE CAUSE
Output voltage low or high. • IAT sensor circuit open or short.
• IAT sensor malfunction.
• ECM malfunction.
()
0.15 V Sensor voltage 4.85 V<
without the above range.
1
ECM couplers
n
j
V
2
• Remove the front box. (
:
9-18)
1
2
Ye s
Ye s
No
No
Turn the ignition switch OFF.
Measure the IAT sensor resistance.
;
IAT sensor voltage: 4.5 – 5.5 V
+
Dg –
-
Ground
+
Dg –
-
B/Br
z
09900-25008: Multi circuit tester
u
Tester knob indication: Voltage (
-
)
(
)
Loose or poor contacts on
the ECM coupler.
Open or short circuit in the
Dg wire or B/Br wire.
;
IAT sensor resistance:
Approx. 2.45 kΩ at 20 ˚C (68 ˚F) (Terminal – Terminal)
z
09900-25008: Multi circuit tester
t
Tester knob indication: Resistance (Ω)
Replace the IAT sensor
with a new one.
Replace the ECM with a new
one, and inspect it again.
Turn the ignition switch OFF.
Check the IAT sensor coupler for loose or poor contacts.
If OK, then measure the IAT sensor voltage at the wire
side coupler.
Disconnect the coupler and turn the ignition switch ON.
Measure the voltage between Dg wire terminal and
ground.
If OK, then measure the voltage between Dg wire termi-
nal and B/Br wire terminal.
NOTE:
IAT sensor resistance measurement
method is the same way as that of the
ECT sensor. Refer to page 8-13 for
details.
Dg or B/Br wire open or shorted to ground, or poor
j
or
n
connection.
If wire and connection are OK, intermittent trouble or faulty
ECM.
Recheck each terminal and wire harness for open circuit
and poor connection.
Intake Air Temp. Resistance
20 ˚C ( 68 ˚F) Approx. 2.45 kΩ
50 ˚C (112 ˚F) Approx. 0.808 kΩ
80 ˚C (176 ˚F) Approx. 0.322 kΩ
110 ˚C (230 ˚F) Approx. 0.148 kΩ
Ω
B/Br
Dg