ENGINE GENERAL INFORMATION AND DIAGNOSIS (M13 ENGINE) 6-2-77
3 Check ECM voltage.
1) Disconnect connector from ECT sensor with
ignition switch turned OFF.
2) Check for proper connection to ECT sensor
at “YEL/GRN” and “BRN/WHT” wire termi-
nals.
3) If OK, then turn ON ignition switch, check
voltage between “YEL/GRN” wire terminal
and vehicle body ground. See Fig. 1.
Is voltage about 4 – 6 V?
Got to Step 6. Go to Step 4.
4 Check ECT sensor circuit insulation.
1) Disconnect connectors from ECM with igni-
tion switch turned OFF.
2) Measure resistance between “YEL/GRN”
wire terminal of ECT sensor connector and
body ground.
Is resistance infinity?
Got to Step 5. “YEL/GRN” wire shorted
to ground circuit.
If wire are OK, substitute
a known-good ECM and
recheck.
5 Check ECT sensor short circuit.
1) Turn ON ignition switch.
2) Check voltage between “YEL/GRN” wire
terminal of ECT sensor connector and vehi-
cle body ground.
Is voltage about 0 V?
Got to Step 6. “YEL/GRN” wire shorted
to other circuits.
If wire are OK, substitute
a known-good ECM and
recheck.
6 Check ECT sensor according to “Engine Cool-
ant Temperature Sensor (ECT Sensor) Inspec-
tion” in Section 6E2.
Is it in good condition?
Substitute a known-good
ECM and recheck.
Replace ECT sensor.
Step Action Yes No
[A]: Fig. 1 for Step 3
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