Month: August 2015
Nissan Cefiro A32 engine idle shake fault
A 97-year Nissan Cefiro A32 sedan (engine type VQ30DE, VIN code: JN1CCUA32V0001253), at the start, feeling the body shake, when start and first gear change to second gear, the fault is most obvious, middle, high speed vehicle operation normal.
Fault Diagnosis and Analysis:
First use Consult3 III read fault code, the system displays normally. Read the main parameters data stream as follows:
Camshaft sensor angle signal: 825RPM
Air flow sensor: 1.32 V
Coolant temperature sensor: 89 ℃
Battery voltage: 13.6 V
Throttle position sensor: 2.52 V
Throttle fully closed position: OFF
Air conditioner switch signal: OFF
Injector pulse width: 3.7MS
Ignition timing: 19BTDC
Idle Control Valve: 36.0%
According to the data stream can be seen: the problem is the throttle body position sensor did not adjust well or throttle body too dirty. Then, remove the throttle body cleaning and adjusting the throttle position sensor, cleaning fuel injectors, replace spark plugs and fuel filter. After installed test the car, the fault persists. Next, check the EGR system and activated carbon canister control system, no problems found. Use Nissan Consult Diagnosis Interface to measure the sensor signals, also no problems found. Finally would be analyzed the fault by measuring the exhaust.
Exhaust emission data are as follows: CO is 1.3%, HC is 600 × 10-6, for electric vehicles is clearly excessive; then measure the ignition waveform found: each cylinder high-pressure significantly weaker, at around 8 KV, through the exhaust and ignition waveform analysis, the problem is clearly in the high-pressure part, is high-pressure fire energy weakened caused by the engine power insufficient.
It has replaced six ignition, but fault persists. Check the ignition system according to the circuit diagram found that the ignition system have capacitor by itself, then think whether the capacitor damage caused by the failure? With this problem to check capacitors. Remove and measure the capacitor, found it breakdown, the primary voltage from here to the grounding, thus weakening the ignition energy.
Troubleshooting: Replace capacitors, test the car, fault disappears.
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Audi A6L car airbag warning
A 2012 year Audi A6L with mileage of about 23,000 km, the car airbag warning.
Diagnosis:
1, Using the VAS 5054A ODIS 2.2.4 read 15 have fault code: 9444649 B 101 D29 [137] belt switch, passenger side, unreliable signal.
2, Check the line properly, try replacing the belt switches, the fault can not be ruled out. Since the airbag control unit can not be replaced, order a new control unit, can not be encoded after installation, find out has a software management code XCHG15AO05, after upgrade also can not be encoded, upgrade again, display can only upgrade once.
3, Consulting researchers, told the airbag control unit is locked, VAS 5054A authority is not enough, use VAS 5054A directly programmed into coding, fault resolution.
4, After the vehicle stopped one night, airbag lamp lights up again, displayed the side of copilot airbag static fault, check the lines and contact normal, again after all the airbag system installed properly, the fault becomes sporadic, can be cleaned, and then place one day fails again appears and can not be cleared.
5, Analysis, the new control unit should not be damaged, focused on checking the wiring harness pins and the contact (as shown Figure 1), recall previously processed A4B6 airbag system are all pin contact poor, open pin can not see fault by the naked eye, try 31,32 pin to pry tightly by tool, observed after installed, fault resolution.
Fault resolution: use VAS 5054A and diagnostic software ODIS. After deal with airbag control unit pin, fault resolution.
VAS5052A authority is not enough, it can not be encoded, but use VAS 5054A with ODIS under normal circumstances can be encoded. Because for airbag alarm, check the wiring harness, plug several times airbag computer plug, causing some pins loose, naked eye can not distinguish, will appears secondary failure, so when repair must be careful to plug airbag system wiring harness, moving as little as possible.
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