1A-102 Engine Control System (4JJ1)
3
Observe the Intake Air Temperature (IAT) Sensor
parameter with a scan tool.
Is the IAT Sensor parameter more than the
specified value?
4.8 volts
Go to Step 4
Go to Diagnostic
Aids
4
1. Turn OFF the ignition.
2. Disconnect the mass air flow/ intake air
temperature (MAF/ IAT) sensor harness
connector (Euro 4 specification) or the IAT
sensor harness connector (expect Euro 4
specification).
3. Connect a DMM between the signal circuit
(pin 4 of J38 [Euro 4 specification] or pin 1 of
J217 [expect Euro 4 specification]) and a
known good ground.
4. Turn ON the ignition, with the engine OFF.
Is the DMM voltage more than the specified value?
5.5 volts
Go to Step 5 Go to Step 6
5
Important: The IAT sensor may be damaged if the
sensor signal circuit is shorted to a voltage source.
1. Test the signal circuit between the ECM (pin
72 of J14) and the IAT sensor (pin 4 of J38
[Euro 4 specification] or pin 1 of J217 [expect
Euro 4 specification]) for the following
conditions:
• A short to battery or ignition voltage
• A short to the 12 volts reference
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
—
Go to Step 15 Go to Step 14
6
Connect a 3-amp fused jumper wire between the
signal circuit and the low reference circuit (pins 4
and 5 of J38 [Euro 4 specification] or pins 1 and 2
of J217 [expect Euro 4 specification]).
Is the IAT Sensor parameter less than the specified
value?
0.1 volts
Go to Step 10 Go to Step 7
7
Connect a 3-amp fused jumper wire between the
signal circuit (pin 4 of J38 [Euro 4 specification] or
pin 1 of J217 [expect Euro 4 specification]) and a
known good ground.
Is the IAT Sensor parameter less than the specified
value?
0.1 volts
Go to Step 9 Go to Step 8
8
1. Test the signal circuit between the ECM (pin
72 of J14) and the IAT sensor (pin 4 of J38
[Euro 4 specification] or pin 1 of J217 [expect
Euro 4 specification]) for an open circuit or
high resistance.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
—
Go to Step 15 Go to Step 12
Step Action Value(s) Yes No
LG4JJED-WE-0871.book 102 ページ ２００８年４月４日 金曜日 午前９時６分
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