Passat 1.8T can not start failure

Passat 1.8T can not start failure Model: Passat 1.8T Passat
; Mileage: 2025km
Symptom:
A 2007 production of Shanghai Volkswagen Passat 1.8T Passat automatic transmission car, engine and equipped with BGC 01V tiptronic 5 speed transmission, mileage 2025km. Rescue phone owners play reflected in the case of the red car in motion when the engine suddenly stop, can not start the car several times. Rescue workers rushed to the scene to conduct a preliminary examination, the ignition switch ON state, the dashboard lights and brake pedal in addition to EPC light is off, the other information shows no abnormalities. Try to start the engine, the engine can start, but after running for about 1s, then off. Try to start the fault persists, the overall feel of the phenomenon with a similar engine immobilizer, but K117 does not light or alarm light flashing, then dragged into the car repair station for further examination.
Failure Analysis:
Connect VAS5052 fault diagnostic apparatus, the engine control unit J220 query failure memory, display identification to a fault code :18056 - transmission data bus failure. And the fault code can not be cleared, non-accidental failure. Select the data block options, read out the engine control unit and power system data bus for communication between control units of other measurements, display group 125: Transmission 0, instrument cluster 0; 126 display group: airbag 0, indicating that J220 and transmission and airbag control units communicate all interrupt.
Passat 1.8T automatic car CAN data bus power system equipment on the engine control unit J220, automatic transmission control unit J217, instrument cluster control unit J285, ABS control unit J104 and airbag control unit J234, this time with necessary to enter the gateway using VAS5052 fault diagnostic control unit J533, with a view to check the gateway's CAN data bus power system communication status, to determine the engine control unit on the data bus can not communicate the nature of the fault that data to determine the cause of the malfunction bus has been disrupted, or local data bus link short-circuit or open circuit occurred.
Integrated into the gateway in the instrument control unit J533 check fault code :01314 - engine control unit is no communication, currently exist; 01315-- transmission control unit is no communication, occasional. Clear the fault code execution operation, 01,314 can not be deleted. Select the data block options, read the measurement value display group 125: Engine 0, transmission 1; 126 set to a measured value: the airbag 1. The examination shows that the gateway system in addition to the engine and power control unit other than the normal communication, nature of the fault belongs to the engine control unit and power system data bus between the local circuit.
1s from the engine can start running the analysis of phenomena, the engine control unit power supply should be no problem, VAS5052 access to the engine control unit can also prove that the normal power supply, which determine the J220 engine control unit can not communicate for two reasons: First, the engine control unit and data bus connected to external interrupt lines, and second, the engine control unit J220 in the CAN data bus transceiver circuit part of the damage occurred. Based on the above analysis, the next step just check the external power system CAN line data bus will be able to determine the cause of the fault condition.
Access to BGC engine circuit, find the side of the engine control unit wiring harness connector in the T121/58, T121/60, and combination meter control unit wiring harness side connector of the T32b/20, T32b/19, respectively, for the power system data bus CAN-L (orange / brown) and the CAN-H (orange / black) terminals. Disassemble the engine control unit connector and combination meter control unit of the green connector, measuring J220 and J285 connector harness side connector harness side corresponding to the terminals of continuity. Measurement results show that, J220's and J285's T32b/20 T121/58 terminal resistance between terminals as 0.2Ω, J220's and J285's T32b/19 T121/60 terminal resistance between terminals as 0.5Ω, indicating that J220 and J285 between The link does not disconnect the external data bus. According to the inspection concluded that, since the external data bus line is normal, cause of the malfunction can be identified as the engine control unit of the data bus transceiver is a problem.
Replacement of the engine control unit, the ignition switch to the ON position, instrument lights and brake pedal on the EPC light is on. Connect VAS5052 fault diagnostic re-enter the gateway J533, access to the data block group 125 shows the measured values, shown as: engine 1, transmission 1. This indicates that the engine control unit and data bus traffic returned to normal. Remove the control unit stores the fault code, read out with a password to read the car's instrument four security password, enter the leading options to complete the encoding of J220 and J220 and J285 match between the security of the throttle control unit J338 basic settings. Complete this series of operations, start the engine, the engine starts running smoothly, the road test to confirm the engine is working properly in all conditions, failure ruled out.