Engine General Information and Diagnosis: 1A-74
3
MAF sensor and its circuit check
1) With ignition switch turned OFF, connect scan tool to
DLC.
2) Start engine and warm up to normal operation
temperature.
3) Check MAF value using scan tool. (Refer to “Scan Tool
Data: ” for normal value.)
Is each value within specified range?
Go to Step 11.
Go to Step 4.
4
MAF sensor output voltage check
1) Turn OFF ignition switch.
2) Remove ECM from its bracket with ECM connectors
connected.
3) Measure voltage between “C37-26” and “C37-27”
terminals of ECM connector referring to “Mass Air Flow
(MAF) and Intake Air Temperature (IAT) Sensor On-
Vehicle Inspection: in Section 1C”.
Is each value within specified range?
Poor “C37-26” and/or
“C37-27” terminal
connection.
If OK, substitute a
known-good ECM and
recheck.
Go to Step 5.
5
MAF sensor power supply voltage check
1) Disconnect connector from MAF and IAT sensor with
ignition switch turned OFF.
2) Turn ON ignition switch, measure voltage between
engine ground and “BLU/BLK” wire terminal (2) of MAF
and IAT sensor connector (1).
Is voltage 10 – 14 V?
Go to Step 6.
“BLU/BLK” wire is open
circuit.
6
MAF sensor ground circuit check
1) Turn OFF ignition switch, measure resistance between
“BLU” wire terminal of MAF and IAT sensor connector
and engine ground.
Is resistance below 5
Ω
?
Go to Step 8.
Go to Step 7.
7
Ground circuit check
1) Measure resistance between “C37-27” terminal of ECM
connector and vehicle body ground.
Is resistance below 5
Ω
?
“BLU” wire is open or
high resistance circuit.
ECM grounds “C37-58”,
“C37-48”, “C37-30”,
“C37-29” and/or “C37-
15” circuit is open or
high resistance.
If wires are OK,
substitute a known-
good ECM and recheck.
Step
Action
Yes
No
I4RS0A110020-01
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