Symptom: 2009 annual magotan a car, mileage 6 830 km, the user may reflect the high vehicle coolant temperature (FIG. 1).
Check Analysis: maintenance personnel take the car did not find fault phenomenon, the engine control unit with VAS5052A detection, fault code 06468 P1944mdash; mdash; cooling fan control unit a high temperature (FIG. 2). Check the cooling fan is running at this time, the water temperature gauge indicates normal. For failure to reproduce, this car had a long standing test. Finally appeared to third failure, check the concept does not turn found a small fan, a large cooling fan is not operating normally, the coolant temperature was increased (FIG. 3). The car lift, observe the fan header found no abnormalities. The plug pulled, the pin loosening Discovery 4 (FIG. 4). After the plug handle, cooling fan is running, the coolant temperature is normal.
road test, the fault occurs again. At this time, a small fan disconnect the plug, instead of the fan with access test light, test light is off, the fan control unit outputs no power.
Solution: Replace the fan control unit, failure to completely eliminate. The time required to re-users, users complained that the failure does not occur again.
reviewed: for sporadic fault to believe there is a fault, the fault must let reproduced. In this case, although a long time to test, but find the exact point of failure, avoiding rework encountered such failures often arise, won the trust of users. Further, since the plug loose, resulting in premature failure of the fan control unit, if not carefully test, also possible to let the point of failure.