Lifan 620. Manual — part 46

(4) HECU voltage of 10 ~ 12V is preferred during exhaust mode operation. As battery on

vehicle is used when using diagnostic instruments, there should be no problem. (If

exhaust mode operation is repeated with high voltage, ECU coil may be damaged.)

4. Exhaust fault confirm methods (Table 3-21)

Table 3-21

Leak experiment

Difference

Type

ECU

operation

Excessive leak

Minim leak

Remark

Case 1

Normal

O.K

O.K

Normal operation, no rework

Case 2

Normal

O.K

N.G

Abnormal operation, rework

Case 3

Normal

N.G

N.G

Abnormal operation, rework

Case 4

No

O.K

O.K

Abnormal operation, rework

exhaust and filling in HECU can not be operated).

(5) After stepping on the brake pedal, open the bleed screw on the caliper or drum brake

to exhaust the inside air. This operation should be carried out for all wheels before that

the brake fluid exhausted through the bleed screw contains no air and the brake pedal is

hard enough. When using the reassembled equipment that can form vacuum or is filled

with brake fluid, refer to item (10).

(6) Operate the exhaust mode with the reassembled equipment or diagnostic instrument

and step on the brake pedal, if there is no reaction force, repeat stepping on and

releasing the pedal until the exhaust mode is finished. (Exhaust mode: repeat the

process of start and stop of normally closed solenoid valve with interval of 2 seconds for

1 minute, and keep motor working. The repeat of stepping on and releasing of pedal

should be carried out on the normally closed solenoid valve while motor is operating.)

185

(7) Rework of operation of item

(exhaust) should be carried out for all wheels.

⑤

(8) Measure the play of brake pedal; if not in compliance with specification, repeat the

processes in item

(exhaust mode) and item

(exhaust). If the brake pedal

⑥

⑤

play still

does not comply with specification after over 10 repeats of exhaust mode and exhaust

operation, replace with spare HECU (wet) and then restart the operation.

(9) Connect the reassembled equipment and diagnostic instrument to HECU to recheck

whether there is still a DTC. If yes, delete the DTC, and then disconnect the

reassembled equipment or diagnostic instrument.

(10) When using other reassembled equipments (that can produce vacuum or is filled

with liquid), the methods are as follows.

1) Operate in process as described in item (1) - (4) above;

(4) Operate the exhaust mode with the reassembled equipment or diagnostic instrument

and step on brake pedal, if there is no reaction force, repeat stepping on and releasing

the pedal until exhaust mode is finished.

(5) Rework of operation of item (3) (exhaust) should be carried out for all wheels.

(6) Measure the play of brake pedal; if not in compliance with specification, repeat the

processes in item (4) (exhaust mode) and item (3) (exhaust). If the brake pedal play still

does not comply with specification after over 10 repeats of exhaust mode and exhaust

operation, replace with spare HECU (wet) and then restart the operation.

(7) Connect the reassembled equipment and diagnostic instrument to HECU to recheck

whether there is still a DTC. If there is still a DTC, disconnect the reassembled

equipment or diagnostic instrument.

186

Appendix I:

Fault Cases and Mistaken Repair Cases

HECU mistaken repair cases:

1. HECU replacement concerning ABS working sound

Case of HECU replacement for misjudging sounds of solenoid valve and motor as fault

when ABS is working

It is normal that there is noise during brake pressure decrease or increase when ABS is

working. The volume of noise varies according to different pressures to all wheels. It is

Air gap adjustment method: After confirmation of part with abnormal air gap, replace or

burnish the mounting surface (contact area) of sensor and adjust to the specified air gap;

when disturbance occurs, a thin washer should be placed on the surface of sensor and

then adjust to specified air gap.

187

Appendix II:

ABS Common Sense

1. If braking distance will be shorter after installing ABS?

According to experimental statistics, the braking distance will be shorter (about 5% ~

20%) on most roads; but it can be longer on some special roads (like snow, non-asphalt

and uneven roads), but with stable steering.

2. What are the main purposes of ABS?

The main purpose of ABS is to prevent block. The functions are as follows:

the brake force will increase while the turning and stabilizing force will decrease if to

brake when turning. The two kinds of forces can be adjusted to the best on the vehicle

with ABS; but they can not be adjusted on the vehicle without ABS, which will weaken its

steering performance and stability.

If the two kinds of forces are too small (For example, the vehicle will leave the running

route as the speed is too high when drifting), the force to adjust the vehicle is too small,

the ABS effect is not obvious. In a word, deceleration in advance and safe turning is the

best solution.

188