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FI SYSTEM DIAGNOSIS 4-53
“C21” (P0110-H/L) IAT SENSOR CIRCUIT MALFUNCTION
INSPECTION
Step 1 (When indicating C21:)
1) Turn the ignition switch OFF.
2) Lift and support the fuel tank. (5-3)
3) Check the IAT sensor coupler for loose or poor contacts.
If OK, then measure the IAT sensor voltage at the wire side
coupler.
4) Disconnect the coupler and turn the ignition switch ON.
5) Measure the voltage between Dg wire terminal A and
ground.
6) If OK, then measure the voltage between Dg wire terminal A
and B/Br wire terminal B.
IAT sensor input voltage: 4.5 – 5.5 V
(+ Dg – - Ground)
(+ Dg – - B/Br)
09900-25008: Multi-circuit tester set
Tester knob indication: Voltage ()
Is the voltage OK?
DETECTED CONDITION POSSIBLE CAUSE
C21 Output voltage is not within the following
range.
0.15 V Sensor voltage < 4.85 V
• IAT sensor circuit open or short
• IAT sensor malfunction
• ECM malfunction
P0110
H
Sensor voltage is higher than specified
value.
• IAT sensor circuit open or ground circuit open
• IAT sensor circuit shorted to ground
L
Sensor voltage is lower than specified
value.
ECM
B/Br
E2
IAT
Dg
IAT sensor
1
V
1
YES Go to Step 2.
NO
• Loose or poor contacts on the ECM coupler
(terminal Q or S)
• Open or short circuit in the Dg wire or B/Br wire