2.18.3 Diagnostic Information and Procedures
2.18.3.1 Cooling Fan Circuit Diagnosis
Diagnostic Tips:
–
If there is an overheating complaint, verify whether the it is because the engine coolant boiling or the engine coolant temperature
gage indicates the coolant overheating. If the engine is overheating, but the cooling fan is still running, check the engine cooling
system.
–
If the fuse EF29 in underhood fuse block fuses immediately after installation, check whether the circuit between the cooling fan
high or Low-Speed relay and cooling fan motor is to short to ground. If the engine control module has just controlled relay pull-
in, EF29 fuses, then the cooling fan motor may be faulty.
–
When the Air-Conditioning system is switched on, the engine control module controls the cooling fan run at low speed. When
the Air-Conditioning high pressure is 1,520 Pa (220.5 psi), the engine control module will switch cooling fan from low speed to
high speed. When the Air-Conditioning high pressure drops back to 1,450 kPa (210.3 psi), the cooling fan will return to low speed.
–
Use scan tool "Function Test" to drive high or low speed cooling fan relay pull-in to confirm whether the fan works properly to
quickly determine the fault.
Note
Before carry out this diagnostic procedure, make sure check whether fuse EF29 works properly, whether main relay
works properly. When using scan tool "action test", make sure the scan tool communicates with ECM properly.
Step 1
Verify the fault.
Next
Step 2
Confirm whether the low speed cooling fan is running.
(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 A/C switch.
(e)
Select in sequence: Engine / Data List / Engine Coolant
Temperature.
(f)
When the engine coolant temperature gage displays 95°C
(203 ºF) Cooling fan should be running at low speed.
Is cooling fan running at Low speed?
No
Yes
Step 3
Confirm whether the high speed cooling fan is running.
(a)
Turn off A/C switch.
(b)
When the engine coolant temperature gage displays 99°C
(210.2 ºF) When the cooling fan should be running at high
speed.
Is the cooling fan running at high speed?
2-840
Engine Cooling System JL4G15-D
Engine
EC718/EC718RV EC715/EC715RV 10/2009
Summary of Contents for EC715 2009
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