a 2008 annual Buick Excelle sedan. The car reflects the owner may not start, but the starter operating normally. Whether hot or cold car start, there will be failures. Failure frequently occurs several times a day, but after switching off the ignition, the car will be able to restart.
First, I take the car verification failure phenomenon, connect the fuel gauges, to turn the ignition switch ON, the oil pressure was raised to 400 kPa, the starter when starting the normal operation, this time to the normal start, the owner does not reflect the failure phenomenon. TECH-2 engine with fault diagnostic examination, found historical fault codes DTC P1626mdash; mdash; fuel theft loss of signal. See Service Manual, found DTC DTC P1626 set of conditions: the engine control unit (ECM) does not receive the information within the valid key or 1.5 2.0 s, the ignition switch is turned on and an engine control unit (ECM) is not activated.
The description of the owner and the history of suspected trouble codes, the vehicle may not start blocking systems associated with the engine immobilizer, the engine immobilizer blocking systems make a note. It consists of the following components: ignition key, antitheft control unit is mounted on the steering column (with internal antenna), a transceiver, an engine control unit (ECM) and immobilizer indicator (driver side door mentioned, FIG. 1).
FIG 1
When the ignition switch is turned on, the blocker anti-theft system acquires key information by blocking coil. When the blanker control unit reads key code, the key code is stored in the memory unit and compares blanker control. If a valid key is detected, control unit will block the engine control unit (ECM) sends a serial data message correctly. Correct information included in the identification code, to ensure replacement blocker and an engine control unit (ECM) system can not be compromised. If the engine control unit receives invalid information will be performed as follows: closing the fuel injector circuit and the ignition circuit (FIG. 2).
FIG. 2
Figure 3
The description of the owner, not the start of a failure inVehicle use will occur at any time and higher frequency, cold or hot car will appear, and many times I start the car until the fault phenomena, and the owner described the same phenomenon, the starter works fine, but just can not start. In order to verify whether the idle valve is working properly, the author accelerator pedal is depressed slightly, still can not start the engine, then the fuel gauge display 400 kPa, normal pressure, and the fuel pump solved the problem line. Firearms with a test sample, no ignition voltage. At this time the alarm was observed diode light flashes in the driver’s side door stripping, indicating that the engine block immobilizer system is faulty. The ignition position of the ignition switch ON, the body enters a fault diagnostic mdash TECH-2; mdash; blocker mdash; mdash; secure data, see the current key information: ldquo; inconclusive rdquo; (FIG. 3), should show the normal ldquo; rdquo has been read; (FIG. 4).
Figure 4
TECH-2 fault diagnostic apparatus and the ECM communication normally, before restarting the engine key off the fault disappears, in accordance with the above phenomena and fault fault code display, the author concluded that the fault in the ignition key security chip. View key appearance and not the same as the original, ask the owner, that is outside with the key, is recommended to replace the ignition key. After replacing the ignition key and re-start match many times, the fault disappears.
analyze and summarize: the thorniest vehicle maintenance personnel is soft fault (intermittent faults), when the intermittent failure, maintenance personnel should be aware of the phenomenon first-hand detailed interrogation by the driver, such as the failure occurred, temperature and frequency, etc. Because only mastered the conditions of occurrence of a failure, maintenance personnel can gradually be diagnosed by means of an appropriate method.
There are two entry points fault diagnosis, fault symptoms may be further analyzed in accordance with the cause of the malfunction symptoms, no symptoms may be analyzed by historical or current fault fault code. The current DTC will tell us the direction of the fault, the fault code history can tell us a failure that has happened before, using the method of analysis and fault symptom code analysis are combined to diagnose, can shorten the time to diagnosis and improve diagnostic accuracy.
(Zhangze Bo)