2.8.7 Diagnostic information and procedures 

2.8.7.1 Diagnosis descriptions 

Refer to 2.8.2 Description and Operation, get familiar with the system functions and operation 
before starting system diagnosis, so that it will help to determine the correct diagnostic steps, more 
importantly, it will also help to determine whether the situation described by the customer is 
normal. 

2.8.7.2Cooling Fan Circuit Diagnosis 

Diagnostic Hints: 

–  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 overheated, but the cooling fan still runs normally, inspect the engine cooling 
system. 

–  If the fuse EF21 in under hood fuse block fuses immediately blows off after installation, 

inspect whether the circuit between the cooling fan high or Low-Speed relay and ECM is 
short to ground, or the internal short circuit in the ECM. If the fuse EF11 or EF10 in the fuse 
box of the engine blows out just at the pull-in of the relay under the control of the ECM, there 
must be short circuit or cooling Fan motor faults in the Fan relay and Fan motor grounding 
circuits. 

– 

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 the "Function Test"  of fault diagnosis tester 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 carrying out this diagnostic procedure, inspect whether fuse EF21 works properly, 
and whether main relay works properly. When using the "action test" of fault diagnosis tester, 
make sure the fault diagnosis tester communicates with ECM properly. 

1 

Confirm Fault Symptom 

 

2 

Confirm whether the Low-Speed cooling fan runs. 

(a)  Rotated ignition switch to "OFF" position . 

(b)  Connect fault diagnosis tester to diagnosis testing interface. 

(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 gage displays 93  (198.7 

℃

°F) Cooling fan should be 

running at low speed. 

Does the low speed cooling fan run? 

Next 

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3 

Confirm whether the high-speed cooling fan runs. 

(a)  Turn off the A/C switch. 

(b)  When the engine coolant temperature gage displays 96  (196.6 

℃

°F) When the cooling fan 

should be running at high speed. 

Does the high speed cooling fan run? 

4 

Confirm whether the high-speed cooling fan runs. 

(a)  Rotated ignition switch to "OFF" position . 

(b)  Connect fault diagnosis tester to diagnostic interface. 

(c)  Select in sequence: Engine / Data List / Engine Coolant Temperature. 

(d)  When the engine coolant temperature is below 92  (196.6 

℃

°F), Start the engine, turn on the 

A/C switch, cooling fan should be running low speed. 

Does the low speed cooling fan run? 

 

5 

Intermittent fault. refer to2 . 2 . 7 . 3 intermittent fault inspection    . 

No 

Refer to the 8.2.7 Diagnostic Information and Procedures 
in the "Air-Conditioning System" for the A/C system fault. 

Yes 

No 

Refer to 2.8.7.5 Low-Speed Cooling Fan 
Does Not Run 

Yes 

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2.8.7.3 Fault Symptom Table 

Fault Symptom 

Possible Reasons 

Solution 

Cooling Fan Does 
Not Run at High 
Speed 

– 

Fan relay 2 disabled 

– 

Relay 2 coil circuit open fault 

– ECM 

– 

Water temperature sensor signal error 

Refer to 2.8.7.4 High-Speed 
Cooling Fan Does Not Run 

Cooling Fan Does 
Not Run at Low 
Speed 

– 

Fan relay 1 disabled 

– 

ECM Internal Circuit Open 

– 

Fan Motor 1 internal coil circuit open 
fault 

– 

Fan Motor 2 internal coil circuit open 
fault 

– 

Relay 2 internal electric shock fault 

– Open 

Circuit 

– 

Water temperature sensor signal error 

Refer to 2.8.7.5 Low-Speed 
Cooling Fan Does Not Run 

Fan 2 Stops 
Running (Fan 1 
Runs at High 
Speed stop) 

– 

Circuit from fan 1 to relay 2 is short 
to the ground 

– 

Relay 2 has no electric shock return 

Refer to 2.8.7.6    Cooling Fan 
1 Runs At High Speed (Fan 2 
Does not Run) 

Cooling Fan 
Always Runs at 
High Speed 

– 

Water temperature sensor signal error 

– 

ECM internal ground short circuit 

– 

The circuit from high-speed relay box 
to engine is short to the ground 

Refer to 2.8.7.7 Cooling Fan 
always Runs at high Speed 

Fan 1 Stops 
Running (Fan 2 
Runs at High 
Speed stop) 

– 

Fan relay 1 disabled 

–  Fan relay 1 coil circuit and control 

circuit open fault 

– 

Motor 1 internal coil circuit open 

– 

Circuit open between motor 1 and fan 
relay 2 

– 

Relay 2 pull-in contact fault 

– 

ECM internal circuit open 

Refer to2.8.7.5 Cooling Fan 
always Runs at Low Speed 

 

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2.8.7.4 High-Speed Cooling Fan Does Not Run 

Note: Before carry out this diagnostic procedures, please refer to the2.8.7.2 Cooling Fan Circuit 
Diagnosis, which will facilitate the Diagnostic. 

1 

Inspect the power supply circuit between the cooling fan’s high- and low-speed relay 2 
coil. 

 

(a)  Rotated ignition switch to "OFF" 

position . 

(b)  Dismantle the cooling fan high- 

or low-speed relay 2. 

(c)  Rotated ignition switch to "ON" 

position . 

(d)  Measure voltage between relay 

socket #85 and vehicle body 
ground with a multimeter. 

Standard Voltage: 11-14 V 

NL11-2250b

ER03

8 5

86

8 7

30

3 0

87

8 6

8 5

ER05

3 0

8 7

86

85

ER06

30

87

87 a

8 6

8 5

ER11

ER08

ER

09

8 5

8 6

87

3 0

4

ER10

2

1

5

3

4

2

1

5

3

4

2

1

5

3

ER04

4

ER02

2

1

5

3

4

2

1

5

3

ER01

ER07

4

2

1

5

3

1

2

3

4

11

12

13

14

15

16

5

6

7

8

9

10

EF0

8

EF0

7

EF2

7

EF2

6

EF2

2

EF2

9

EF

0

3

EF

0

6

EF

0

9

EF2

5

EF1

7

EF1

6

EF1

5

EF

3

5

EF2

1

EF1

4

EF

01

EF

02

EF

04

EF

10

EF

1

1

EF1

8

EF2

4

8 5

Confirm if the voltage conforms to standard value. 

 

2 

Inspect the coil grounding circuit between the cooling fan’s high-speed and low-speed 
relay 2. 

(a)  Rotated ignition switch to "OFF" position . 

(b)  Dismantle the cooling fan high- or low-speed relay 2. 

(c)  Disconnect ECM harness connector EM01. 

(d)  Measure the continuity between the cooling fan high- or low-speed relay 2 socket #86 and 

ECM harness connector EM01 terminal 17. 

Standard Resistance: Less than 1 Ω 

Confirm whether the resistance conforms to standard value. 

 

3 

Inspect the voltage of the terminal 17 of BCM wire harness connector EM01. 

(a)  Rotated ignition switch to "ON" position . 

No 

Check circuit fault between cooling fan low speed relay 2 
plug No. 86 and ECM harness connector EM01 terminal 
No. 17

Yes 

No 

Fuse relay box in the engine cabin is 
broken down, and replace if necessary. 

Yes 

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