2.8.7 Diagnostic Information and Procedures
2.8.7.1 Diagnosis Description
Get familiar with the system functions and operation before start system diagnostics, so
that it will help to determine the correct diagnostic steps, more importantly, it will also help to determine whether the customer
described situation is normal.
2.8.7.2 Cooling Fan Circuit Diagnosis
Diagnostic Tips:
–
If a customer complains an overheating fault, verify whether it is because the engine coolant boiling or the engine coolant
temperature gage is indicating overheating. If the engine is overheated, but the cooling fan still runs normally, check the engine
cooling system.
–
If the underhood fuse EF29 fuses immediately after installation, check whether the cooling fan high and low speed relay and
cooling fan motor wire is short to ground. If the fuse fuses immediately after the engine control module pull-in, then the cooling
fan motor may be faulty.
–
When the air-conditioning system is running, the engine control module controls the cooling fan running at low speed. When the
air-conditioning high pressure reaches 1,520 kPa (220.5 psi), the engine cooling fan control module will switch the cooling fan
from low to high speed. When the air-conditioning high pressure drops back to 1,450 kPa (210.3 psi), the cooling fan will return
low-speed.
–
Scan tool can be used in the "Function Test" to drive high or low speed cooling fan relay pull-in. Check whether the fan works
normally in order to quickly determine the fault.
Note
Before carry out this diagnostic procedures, check whether the underhood fuse EF29 is normal and main relay is
working properly. When use scan tool "Action Test", make sure the scan tool communication with ECM is normal.
Step 1
Verify the fault.
Next
Step 2
Confirm whether the Low-Speed cooling fan runs.
(a)
Turn the ignition switch to "OFF" position.
(b)
Connect scan tool to the datalink connector.
(c)
Start the engine to normal working temperature.
(d)
Turn off the A/C switch.
(e)
Select in sequence: Engine / Data List / Engine Coolant
Temperature.
(f)
When the engine coolant temperature displays 95°C
(203 ºF) the cooling fan should be running at low speed.
Does the low speed cooling fan run?
No
Refer to
Yes
Step 3
Confirm whether the high-speed cooling fan runs.
(a)
Turn off the A/C switch.
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Cooling System JL4G18-D
Engine
EC718/EC718RV EC715/EC715RV 10/2009
Summary of Contents for EC715 2009
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