6-2-70 ENGINE GENERAL INFORMATION AND DIAGNOSIS (M13 ENGINE)
Troubleshooting
Step Action Yes No
1Was “Engine and Emission Control System Check” per-
formed?
Go to Step 2. Go to “Engine and
Emission Control
System Check” in
this section.
2 MAF sensor check.
1) Connect scan tool to DLC with ignition switch turned
OFF.
2) Start engine and check MAF value displayed on scan
tool. (Refer to “Scan Tool Data” in this section for nor-
mal value.)
Is normal value indicated?
Intermittent trouble.
Check for intermit-
tent referring to
“Intermittent and
Poor Connection” in
Section 0A.
Go to Step 3.
3 Check MAF sensor power supply voltage.
1) Disconnect connector from MAF sensor with ignition
switch turned OFF.
2) Turn ON ignition switch, measure voltage between
engine ground and “BLK/RED” wire terminal of MAF
sensor connector.
Is voltage 10 – 14 V?
Go to Step 4. “BLK/RED” wire in
open circuit.
4 Check MAF sensor ground circuit.
1) Measure resistance between “RED” wire terminal of
MAF sensor connector and engine ground.
Is resistance below 5
Ω
?
Go to Step 6. Go to Step 5.
5 Check ground circuit.
1) Disconnect connectors from ECM with ignition switch
turned OFF.
2) Remove ECM from vehicle body and connect connec-
tors to ECM.
3) Measure resistance between “E22-32” terminal of
ECM connector and vehicle body ground.
Is resistance below 5
Ω
?
“RED” wire in open
or high resistance
circuit.
ECM grounds “E22-
1”, “E23-1” and/or
“E23-2” circuit in
open or high resis-
tance.
If wires are OK, sub-
stitute a known-good
ECM and recheck.
6 Check MAF sensor signal circuit.
1) Disconnect connectors from MAF sensor and ECM
with ignition switch turned OFF.
2) Measure voltage between “WHT” wire terminal of
MAF sensor connector and engine ground.
Is voltage 0 V?
Go to Step 7. “WHT” wire shorted
to others circuit.
7 Check MAF sensor output signal
1) Connect connector to MAF sensor with ignition switch
turned OFF.
2) Check voltage between “E22-14” and “E22-32” under
the following condition.
Voltage between “E22-14” and “E22-32” of ECM con-
nector at ignition switch ON, leaving engine OFF: 0.5
– 1.0 V
Idling: 1.0 – 1.8 V
Is each value as specified?
Substitute a known-
good ECM and
recheck.
Faulty MAF and IAT
sensor.
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