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Do not overcome example of corrective maintenance of CLASS2 communication networ
From;    Author:Stand originally

Do not overcome example of corrective maintenance of CLASS2 communication network

The breakdown of CLASS2 communication network should notice the following in maintenance:

1, CLASS2 allows as follows to control data is transmitted each other between unit, also allow breakdown to diagnose appearance and these to control unit communication. The BCM that these control unit are department of car of BCM(D-CAR of unit of automobile body control did not receive apply the brake of CLASS2) , electron to control system of unit, air conditioning to control unit, gasbag to control unit, combination system of appearance, power controls unit PCM and key to affirm the system controls unit to wait.

2, a certain control that if join,goes up in CLASS2 data bus line is unit cannot with diagnostic appearance (Tech2) finishs data to exchange, and news report of other control unit is regular, the specification should control unit to have trouble or should control unit to arrive set a data line between SP205 open circuit or contact are undesirable (each control unit passes SP205 join to arrive on CLASS2 bus line) .

3, the voltage when static state of CLASS2 communication network is 0V, the voltage when enabling is 7V. If join each dominate unit data bus line or be disturbed with bus line of data of diagnostic appearance connective, for example bus line is right power source or short circuit of butt joint ground, all can cause all control unit to cannot have regular data news report.

Overhaul example 1:

Breakdown phenomenon: The paragraph did not overcome car of GL8 business affairs 2004, travel course of development 25 thousand Km, car advocate the starter when report starts sometimes does not have reaction, and emergency warning lamp of guard against theft illumes, block an indicator light not to shine, other appearance shows random law changes.

Corrective maintenance: Because the breakdown of this car involved many systems, breakdown phenomenon is more complex, because this diagnoses each system with Tech2 above all,control unit. But when breakdown appears, use Tech2 cannot enter each to control unit. The author thinks, each indicator light that although breakdown phenomenon basically is expressed,goes up in dashboard now is unusual, but the possibility that each appearance indicator light damages at the same time is very little. The signal that blocks signal of a signal, water lukewarm table, speed to express signal, fuel gauge signal and engine revolution counter all comes from dynamical system to control unit PCM, PCM accepts each sensor signal and convey through CLASS2 bus line appearance, because this the most possible trouble site is PCM or CLASS2 bus line.

The power source that checks PCM above all reachs the line that take iron, unusual without discovery. Disconnect the wiring harness outlet on PCM, open ignition switch, 59 in the C1 that measures the wiring harness outlet on PCM sutural right voltage is 5V, and CLASS2 should be 0V about in the voltage when the static state, this explains CLASS2 bus line is put in the place to power source short circuit. For contractible breakdown limits, one by one disconnects the line of each system data that sets a SP205 to go up, should disconnect when the D foot of SP205, the voltage drop on CLASS2 bus line is 0.6V.
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