1A-104 Engine Control System
Diagnostic Aids
Poor connection or damaged harness may cause
intermittents. Check for the following conditions and, if
the fault is detected, repair or replace the faulty portion.
• Poor connection at ECM: Inspect harness
connectors for backed-out pins, improper mating,
broken locks, improperly formed or damaged pins,
and poor pin-to-wire connection.
• Damaged harness: Inspect the wiring harness for
rubbed-through wire insulation or wire broken
inside the insulator. If the harness appears to be
OK, observe the display on Tech 2 while moving
connectors and wiring harnesses related to the
sensor. A change in the display will indicate the
location of the fault.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
3. If the DTC is not detected, the possible cause is
intermittent (intermittent fault).
5. If the output voltage is fixed to 5 V, the possible
cause is open wiring in the circuit. If the output voltage
is fixed to 0 V, the possible cause is short in the circuit.
Step
Action
Value(s)
Yes
No
1
Perform the "On-Board Diagnostic (OBD)
System Check".
Was the OBD System Check performed?
—
Go to Step 2
Refer to OBD
System Check
and go to Step 2
2
Check the IAT sensor connector for
installation and, if mounted improperly,
connect it certainly.
Is the action complete?
—
Go to Step 3
—
3
Review the DTC.
1.
Using Tech 2, check and store the DTC.
2.
Clear the DTC.
3.
Perform test run and review the DTC.
Is DTC22 detected?
—
Go to Step 4
Refer to
Diagnostic Aids
4
Check the IAT sensor output voltage.
1.
Using Tech 2, displays the engine data.
2.
Starter switch "ON", engine "OFF".
3.
Observe the "IAT Sensor" display for
output voltage.
Was the voltage within range?
Approx. 2.8 V
(at 20°C)
Refer to
Diagnostic Aids
and go to Step 13
Go to Step 5
5
Check the IAT sensor output voltage.
Is the voltage fixed to 5 V?
—
Go to Step 6
Go to Step 8
6
Check the IAT sensor circuit for open wiring.
1.
Starter switch "OFF".
2.
Disconnect the ECM.
3.
At the ECM connector pins, measure the
resistance.
Was the resistance within range?
Pins 91-83:
2.5 k
Ω
(ECT:
approx. 20°C)
Go to Step 13
Go to Step 7
Summary of Contents for 4HL1
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