Shenzhen Fu Sheng Electric co.,LTD
ADD：No.1,Block3,Hongchang,Shunchang Street,Pinghu,Longgang District,Shenzhen China
A mileage of about 160,000 km of the public Polaris 1. 8L manual gear manual air-conditioned sedan. The car opened the ignition switch is set to "ON" block, the two cooling fans are low-speed operation, open the air conditioning compressor does not work, and the water temperature warning light flashing alarm.
Cooling fan fault diagnosis and troubleshooting:
Service technician pick up the car, first check the car coolant level, coolant level is normal. According to the car cooling fan working conditions, the following related electrical components were examined, the test results are as follows: The thermal switch on the water tank F18 was checked according to the circuit diagram shows that if the switch internal low gear normally closed can also cause the fan low speed Often turn fault. In order to eliminate the influence of F18, unplug the plug, but the ignition switch is set to "ON" when the fault remains the same. Considering that most Volkswagen car engines have overheat protection, the engine will activate the cooling fan at low speed if the coolant temperature sensor fails. Therefore, the VAS5053 is used to enter the engine control unit 01-03 to read the fault code, indicating that the engine monitoring water temperature signal is not reliable (SP) fault code. Clear the fault code, in order to rule out the possibility of damage to the water temperature sensor, the service technician replaced a new water temperature sensor, read the engine water temperature data flow through 01-08-01, 48 ℃, and the instrument water temperature basically, but this When the instrument on the water temperature warning light flashing.
In order to make the repair process less detours, after the analysis of its circuit diagram, the possible fault points attributed to the following points:
① air conditioning high and low voltage switch G65 damaged。
② air conditioning relay J293 damaged.
③ compressor cut off the temperature sensor G346 damaged.
④ check J293 T14 / 8 feet, air conditioning switching signal is normal。
⑤ Check J293's T14 / 3 feet (engine signal side) level state, to determine whether there is the engine signal source。
⑥ check J293 T4a / 2 feet if there is 12V voltage。
According to the analysis, maintenance technicians conducted a one by one test to check。 As the car has been repaired in other repair shop before, the owner of the fan relay has been replaced, but the fault still。 Try holding attitude or put on a new piece, but the fault still。
The car's air conditioning does not work, will not really have a relationship with G65?
G65 is a 3-wire sensor (white line: signal line; black-blue line: power line; brown line: ground line). Use a multimeter to measure. Connect the power line to 12V normally and the signal line is 2. 5 V, also basically normal. Wiper left below the compressor cut off the temperature sensor G346 unplug the measurement, resistance normal, there is no open circuit phenomenon. The air conditioning relay J293 plug unplugged, the T14 / 3 feet were measured for the ground signal.
But at this moment a bit can not understand, in the engine water temperature is high when the foot of the request signal is high or low。 In order to eliminate the influence of this signal, the pin to the engine control unit J220 is unplugged and the pin is detected as floating。 At this point the air conditioning relay J293 harness after the test, the fault still。 In order to eliminate the adverse effects of air conditioning on and off signals, maintenance technicians in the state of the switch air-conditioning measurement J293 T14 / 8 feet, a state change, the switch signal is normal。 And then on the J293's T4a / 2 feet were measured, the feet are not open air conditioning and air conditioning are 12V。
Check to this, some maintenance mechanic could not figure out, because all the signals affecting the cooling fan and its electrical components have been carefully examined, are normal。 What else will affect the fan? Air conditioning relay J293 In addition to leading to the instrument J285 T14 / 13 feet did not check, leaving a S16 fuse did not check。 Found in the cab left fuse box S16, found to have been blown, replace the fuse, the test, the cooling fan is no longer turned, the air conditioning system also returned to normal。 Nearly two hours of hard inspection, did not expect to actually be a fuse blame。
As the current high-end vehicles widely used CAN-BUS network transmission technology, including power systems, comfort systems, infotainment systems, and through the gateway for data exchange, each control unit has 30 lines, 15 lines Many fuses, so check the system circuit failure, we must first rule out the control unit power supply and grounding part is normal, and then with the diagnostic instrument for fault code reading and systematic signal measurement, so less detours to Eli Improve work efficiency.