Breakdown phenomenon
Produced 2015 on car of steam masses Lang Yi, the oil gas that assembles 1.6L to discharge an amount is amphibious engine, model is CUC, embark 5 block a hand to use transmission, travel course of development 230 thousand Km. The user mirrors lamp of this car EPC to call the police and quickly faint.
Check an analysis
After maintenance technician receives a car, have trial run above all, starting engine and idle fast movement, discovery combines the EPC lamp on appearance to shine, breakdown and user description are consistent. Next VAS6150D examination engine controls use car diagnostic apparatus unit, discovery puts in 2 malfunction code: P064100 -- A of sensor reference voltage, open circuit; P335C00 -- force of high pressure of fuel box pressure sensor, too big signal (graph 1) .
Graph the malfunction code with 1 engine unit control and meaning
Analyse malfunction code and be united in wedlock to maintain the experience of similar breakdown before, maintenance technician is preliminary the cause that the analysis causes this trouble and A of sensor reference voltage are concerned. Before continueing to analyse breakdown, be necessary to introduce the circuit of A of sensor reference voltage first.
The meaning of A of sensor reference voltage is the 5V reference voltage that shows engine controls unit interior to offer. The many sensor that 5V consults voltage passes resistor and in-house monitoring point to give engine provide 5V power supply (graph 2) . The wiring harness of sensor or 5V referenced voltage is right the short circuit that take iron, engine controls the voltage that unit and in-house monitoring point measures to be 0 V, control the malfunction code that unit meeting stores referenced voltage A opens circuit. The function that engine controls unit and internal resistance is sensor or 5V power supply to joining iron short circuit when, prevent burn down engine to control unit.
Graph the circuit of A of voltage of 2 sensor reference
Specific the power supply of which a few sensor that gives engine, relevant maintenance data did not give out specification. The basis services model of accept of new mulberry tower before the experience of similar breakdown, sensor consults voltage A gives door of sensor of engine rotate speed, solar term the seat sensor and quicken footplate sensor to provide 5 V power supply. Then maintenance technician unplugs above all the connector of sensor of engine rotate speed, try cleared malfunction code next, discover sensor A consults the malfunction code of voltage cannot keep clear of. Disconnect with same method again next sensor of position of solar term door and quicken footplate position sensor, malfunction code all cannot keep clear of. Above test indicates trouble is not position of door of sensor of engine rotate speed, solar term sensor and quicken footplate position sensor interior is right the short circuit that take iron causes.
The T3L/1 date terminal that measures sensor of engine rotate speed is right the voltage that takes iron, eventuate 5V, show power supply is normal, the 5V power supply that also indicates sensor of rotate speed of this model engine at the same time is not by sensor referenced voltage A is offerred. The voltage of the T6ad/2 date terminal that measures sensor of position of solar term door, eventuate 0V, the 5V power supply that indicates this sensor is by sensor referenced voltage A is offerred.
The terminal of 5V power supply that the T60/44 terminal that engine controls unit connector is sensor of position of solar term door, take out this terminal, new outfit answers engine to control unit connector, try cleared engine to control unit malfunction code again, discover malfunction code or cannot keep clear of, the power supply wiring harness that shows breakdown is not sensor of position of solar term door causes to joining iron short circuit.
Measure the T6L/1 that quickens footplate position sensor and T6L/2 date terminal the voltage to taking iron, eventuate 0V, the 5V power supply that indicates this sensor is by sensor referenced voltage A is offerred. The T94/58 that engine controls unit connector and T94/80 terminal are the terminal of 5V power supply that quickens footplate position sensor, take out this terminal, new outfit answers engine to control unit connector, try cleared engine to control unit malfunction code again, discover or cannot keep clear of, make clear what cause to joining iron short circuit to breakdown also is not the power supply wiring harness that quickens footplate position sensor.
Is the 5V power supply that still has other sensor by sensor referenced voltage A is offerred? Unplug all sensor of engine, try to read again take malfunction code, discovery or the breakdown that existence sensor A consults voltage opens circuit cannot keep clear of.
Right now, maintenance technician begins to suspect is the open circuit of 5V power supply that engine dominates unit attaint to cause. Then the attempt controls the engine of breakdown car unit installation to arrive on normal traffic, try cleared malfunction code next, discover sensor consults the breakdown of voltage A is kept clear of, show engine controls unit to do not have attaint.
Train of thought of maintenance technician rearrange, undertake an analysis to breakdown, the wiring harness of 5V power supply that still should have certain sensor caused this car trouble to joining iron short circuit. Control the terminal meaning of unit connector through examining engine, be informed pressure sensor burning gas and the 5V power supply that light sensor of gas blowout head is terminal provides the T94/81 number that controls unit by engine. The T94/81 date terminal that controls engine unit connector is taken out, try cleared malfunction code, discover malfunction code is kept clear of, show T94/81 date terminal is right the short circuit that take iron. The wiring harness of this terminal passes wiring harness of engine of join of automobile body wiring harness, arrive at pressure sensor burning gas and sensor of head burning gas finally. So far breakdown reason is found out.
Trouble removal
The short circuit breakdown of wiring harness of join of place of repair T94/81 date terminal, this car breakdown eliminates thoroughly.
Review summary
Be informed through this case, the A of sensor reference voltage of amphibious engine is oil gas the following sensor provide 5 V power supply: Sensor of position of solar term door, quickly footplate position sensor, ignite atmospheric pressure force transducer and light gas blowout head sensor.
