Case 1
Failure phenomenon: a 2007 annual output of 2.5 L Nissan Teana sedan, say users, car headlights turn on automatically function does not work.
Analysis check: Check that the maintenance manual, automatic vehicle headlamp system 3 is mainly controlled by the control unit. The body control module BCM signal transmitted optical sensor, and the transmitted light switch combination meter (the AUTO), the driver’s door switch, the front passenger door switch, rear door switch, an ignition switch (ON / OFF) and the vehicle speed signal determined width light turning on or off, the headlight and tail light circuits. Brightness sensor (FIG. 1) will be transmitted to the ambient light intensity into a voltage signal BCM, BCM intelligent power control command execution unit IPDM the headlights turned associated circuitry.
FIG 1
Related service personnel and the fuse line was examined and found no abnormalities, then the brightness of the light sensors are replaced, but the failure still. The author, after the step of checking the maintenance personnel and related components for analysis, a problem is suspected in the control system, so the use of special fault diagnostic apparatus Nissan CONSULT-3 for the relevant vehicle detection system, the display system trouble code storage. Performing the active test function, the lighting control is normal. They found in the system configuration of the BCM checked problems, BCM communication setting automatic light function display ldquo; no request switch rdquo; (FIG. 2).
FIG. 2
Troubleshooting: The BCM system configuration can be modified to enter manually modified configuration item, the setting modification automatically lighting is ldquo; have request switch rdquo; (FIG. 3). After the system exits, test to determine automatic headlamp function can be used normally.
Figure 3
reviewed: Nissan body control module BCM system having a function of reading, will identify the vehicle mounting hardware and memory. If the artificial modification BCM configuration, it may cause some system does not work, sometimesThese failures maintenance work will bring a lot of trouble.
Case 2
Failure phenomenon: a 2004 Supreme Dongfeng Nissan Bluebird sedan, equipped SR20 engines and RL4F03B hydraulic control of the automatic transmission, mileage 130 000 km. According to users to reflect, and sometimes the car is not good cold start, this failure there have been two months ago, appeared at the beginning of the failure phenomenon is not obvious, a few days there will be a cold start difficult phenomenon, but not just wait for a while It handles the vehicle and can normally start running everything is normal.
Check Analysis: cleaning a car 4S shop through injectors and throttle replaced spark plugs, fuel filter and fuel pump are not troubleshooting. I take the car, first using a dedicated fault diagnostic apparatus Nissan CONSULT-3 is detected on the engine system, trouble code storage system, data monitoring engine is normal. Since the probability of failure associated with starting the fuel system and the intake system before the overhaul has been excluded, maintenance bad start moment, only the first opening and the tightness of the fuel pressure regulator of the idle valve is checked, but also found no problems. According to fault phenomenon, I still think cause of the malfunction in the fuel system, it requires the technician to remove the fuel pump check, when the technician disconnect the fuel pump connector plug, plug has found traces of high temperature deformation, and the oil pump seat pin also significantly trace deformation temperature oxidation (FIG. 4). Since the fuel pump wiring harness connector loose, sometimes leading to supply fuel pump does not work properly, so the pump does not cause the occasional oil, the vehicle can not be started. When after several start-up, the fuel pump harness connector thermal expansion, poor contact disappears, you can successfully start up.
Figure 4
Troubleshooting: an upper seat and the fuel pump connector plug replacement, the fault has not reproduced.
reviewed: When servicing a number of intermittent failures, some failures reflect the details of the user and maintenance projects done for troubleshooting and maintenance staff judge will be very helpful.
(Yang Weijun)