Lifan 620. Manual - part 41

5. Replacement of HECU 

(1) Remove connecting piece of pin 25 and wire harness of HECU in engine compartment when 

engine stops, as shown in Fig. 3-11. 

 

 

 

 

Fig. 3-12 

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(5) Remove the 6 bolts on wet HECU with 6mm hexagonal wrench in a counterclockwise direction, 

as in Fig. 3-13. 

 

 

 

 

 

 

 

 

 

 

 

 

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Section IV    Fault Diagnosis and Troubleshooting 

 

I. Fault Detection Procedure (Fig. 3-15) 

 

 

input and output areas, which may cause occasional dynamic fault or DTC during ECU self-check. 

If fault cause continues, the abnormal part can be detected with reference to DTC table. As 

sometimes fault cause vanishes itself, it is difficult to figure out the real cause. 

In such a situation, faults can be simulated to check if the fault occurs again. 

1. When vibration may be the main reason: 

(1) Shake the connector lightly in all directions; 

(2) Shake the harness lightly in all directions; 

(3) Shake the sensor lightly in all directions; 

(4) Shake the other moving parts (like wheel bearing) lightly. 

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Note: If the harness is twisted off or fractured for tight pull, it must be replaced with new parts. 

Especially when vehicle is moving, the sensor will move up and down, which may cause 

instantaneous open/short circuit. As a result, sensor signal check must be carried out when 

vehicle is moving. 

2. When overheating or supercooling may be the main reason: 

Heat the possibly faulted part with a blower; check for cold welding phenomenon with a cold spray. 

3. When overlarge contact resistance of power supply circuit may be the main reason: 

Open all electrical switches, including the headlight and rear defrosting lamp. If fault does not 

show again, it can only be diagnosed and repaired when it comes out next time. Generally the 

 

Off 

Off 

Off 

Sensor open/short circuit 

Two faults: ABS/EBD unable to start 

On 

On 

Gear ring fault 

Sensor disturbance fault 

One fault: ABS wrong start 

On 

Off 

Wheel 

speed 

sensor 

Air gap fault 

Two faults: ABS and EBD unable to start 

On 

On 

3. DTC read and deletion without fault diagnostic instrument 

(1) Purpose and condition of DTC read without diagnostic instrument 

If no diagnostic instrument is available, ABS fault condition can be indicated and DTC can be read 

through ABS warning lamp, so as to confirm and eliminate the fault. If the DTC is a 2 digital code, 

refer to the number in the bracket of DTC Table in Section 24. 

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