Engine General Information and Diagnosis: 1A-90
3
IAT sensor voltage check
1) Disconnect connector from MAF and IAT sensor with
ignition switch turned OFF.
2) Check for proper connection to MAF and IAT sensor at
“LT GRN” and “GRY/GRN” wire terminals.
3) If OK, then turn ON ignition switch, measure voltage
between “LT GRN” wire terminal of MAF and IAT sensor
connector (1) and vehicle body ground.
Is voltage about 4 – 6 V?
Go to Step 7.
Go to Step 4.
4
ECM voltage check
1) Turn OFF ignition switch.
2) Remove ECM from its bracket with ECM connectors
connected.
3) Check for proper connection of ECM connector at “C37-
25” terminal.
4) If OK, then turn ON ignition switch, measure voltage
between “C37-25” terminal of ECM connector and
vehicle body ground.
Is voltage about 4 – 6 V?
“LT GRN” wire is open
circuit. If wire and
connection are OK, go
to Step 5.
Go to Step 5.
5
Wire circuit check
1) Disconnect connectors from ECM with ignition switch
turned OFF.
2) Turn ON ignition switch.
3) Measure voltage between “LT GRN” wire terminal of
MAF and IAT sensor connector and vehicle body
ground.
Is voltage about 0 V?
Go to Step 6.
“LT GRN” wire is
shorted to other circuit.
If wire is OK, substitute
a known-good ECM and
recheck.
6
Wire circuit check
1) Measure resistance between “C37-25” terminal of ECM
connector and “LT GRN” wire terminal of MAF and IAT
sensor connector with ignition switch turned OFF.
Is resistance below 3
Ω
?
Go to Step 7.
“LT GRN” wire is high
resistance circuit.
7
Ground circuit check
1) Connect connectors to ECM.
2) Measure resistance between “GRY/GRN” wire terminal
of MAF and IAT sensor connector and vehicle body
ground with ignition switch turned OFF.
Is resistance below 3
Ω
?
Go to Step 9.
Go to Step 8.
Step
Action
Yes
No
I5JB0A110037-02
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