6-2-128 ENGINE GENERAL INFORMATION AND DIAGNOSIS (M13 ENGINE)
Troubleshooting
Step Action Yes No
1Was “Engine and Emission Control System
Check” performed?
Go to Step 2. Go to “Engine and Emis-
sion Control System
Check” in this section.
2 Check Relay Circuit
1) Disconnect radiator fan relay from relay box
with ignition switch turned OFF. (See Fig. 1.)
2) Turn ignition switch to ON position.
3) Measure voltage between “BLK/RED” wire
terminal of radiator fan relay connector and
engine ground.
Is voltage 10 – 14 V?
Go to Step 3. “BLK/RED” wire in open
or high resistance circuit.
3 Check Relay Circuit
1) Turn ignition switch to OFF position.
2) Install radiator fan relay to relay box.
3) Disconnect connectors from ECM.
4) Remove ECM from vehicle body and then
connect connectors to ECM.
5) Turn ignition switch to ON position.
6) Measure voltage between “E21-4” wire ter-
minal of ECM connector and vehicle body
ground.
Is voltage 10 – 14 V?
Go to Step 4. Go to Step 6.
4 Check Relay Circuit
1) Turn ignition switch to OFF position.
2) Disconnect connectors from ECM.
3) Remove radiator fan relay from relay box.
4) Measure voltage between “E21-4” wire ter-
minal of ECM connector and vehicle body
ground with ignition switch turned ON.
Is voltage 0 V?
Go to Step 5. “BLU” wire shorted to
power circuit.
5 Radiator Fan Control Signal Check
1) Disconnect negative (–) cable at battery.
2) Disconnect connector from ECT sensor.
3) Connect connectors to ECM.
4) Install radiator fan relay to relay box.
5) Connect negative (–) cable to battery.
6) Measure voltage between “E21-4” wire ter-
minal of ECM connector and vehicle body
ground with ignition switch turned ON.
Is voltage about 0 V?
System is in good condi-
tion.
Substitute a known-good
ECM and recheck.
6 Radiator Fan Control Signal Check
1) Turn ignition switch to OFF position.
2) Install radiator fan relay to relay box.
3) Disconnect connectors from ECM.
4) Measure voltage between “E21-4” wire ter-
minal of ECM connector and vehicle body
ground with ignition switch turned ON.
Is voltage 10 – 14 V?
Substitute a known-good
ECM and recheck.
Go to Step 7.
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