Failure phenomenon: a 2008 model-year Toyota Camry Camry 2.4 L sedan, mileage 35000 km. Users telephone calls to the rescue, reflecting the vehicle can not be started.
check analysis: maintenance personnel arrived at the rescue site, the user first issues were reflected confirmation. When the transmission shift lever is in the P range, the ignition switch to the starting gear when the starter is no reaction, no horn ring, open interior ceiling lamp found brightness is very low, then the initial cause battery power loss is determined can not be started. After speaking with the user know, everything is normal car Shihai morning, noon over the next rain, the evening will not be a car.
in accordance with the usual practice, the maintenance personnel with sufficient amount of the battery on the car assist trigger, but immediately start the auxiliary battery with the original car battery positive electrode power supply line abutment, there is a lot of sparks, according to preliminary judgment on board this phenomenon is not related to high-power lines or place a short circuit of electrical appliances, will produce such a strong spark. Empirically determined, typically the maximum likelihood battery internal short circuit, so the original car battery disconnect grounding line, again connected to the auxiliary starter batteries, have a lot of sparks, it appears to be a problem in other parts of the vehicle. Try to open the ignition switch, the meter display, or no response when starting the starter at this time inside the instrument panel found smoke coming accompanied burnt taste, and immediately disconnect the power cord, the repair station checks towed vehicle .
FIG 1
Because the tobacco smoke from the rear of the instrument, then remove the inspection instrument, the instrument fortunately without burning. Check inside the instrument panel wire harness, the harness has a rear footboard blow marks, this harness is connected to the engine compartment, the engine compartment careful examination revealed also blow the wire harness, then remove the entire instrument panel, all of the internal wiring harness withdrawn, found wherein there are two of the most serious burnt orange line (FIG. 1), whereby the two lines is suspected that the site of the first blow. To check this along two lines, we are actually found grounding line, wherein a terminal metal pedals in the cockpit at the left (FIG. 2), the other one is connected to the grounding line of the engine compartment harness .
FIG. 2
for burning line, the current must be urgentBig surge cause severe fever and eventually cause burning line, and a common cause of a sharp increase in the current mainly two kinds, namely short circuits and overloads. Causes include shorting devices short-circuit and short circuit between the electrical circuit, such as an internal short circuit of electrical equipment, power directly to ground short, at this time has not elapsed since the current collector with a load, current will sharply increases causing blow line. For circuit overload, such as a grounding lines had a number of lines, but because of some bad grounding wire grounding, resulting in a current can not be normal, so a large current through the contact will only be normal grounding line, if this Ground line cross-sectional area is small, it can not afford such a large current, resulting in the grounding line blow.
Poor Ground lead wire seizing the phenomenon is relatively common, over a larger vehicle collisions occur in particular. Since the collision repair detached more body parts, wires, or forget to fasten Ground Ground with a wrench when the bolts are tightened refitted. Some are installed when the grounding line, the grounding point of the vehicle body is painted over after spraying, while the paint without maintenance personnel polished clean the grounding line is fixed, resulting in increased resistance to ground. Although there are these hidden faults, but may all normal, the fault will eventually appear in the latter part of the vehicles over a period of time after the vehicle maintenance. Asks the user car maintenance records and learned that the car had a greater impact accident last year, I was carried out the repairs in other small repair shop, so the author of the grounding line of the vehicle were careful investigation, but found no suspicious areas . Because the point is not to find fault, so it is not rush to replace the wiring harness, or will burn line, maintenance work was in trouble.
3
Since the grounding section and found no problems, do not short-circuit it is? Thus these two blow down the grounding line to the other end of the check, find all of the power supply to the dispenser module fuse box next to the engine compartment, the module main headlamp and speakers to the power supply equipment, installation module there fuses. Since there is a fuse, so if there is a short circuit problem should be the fuse to blow fishes ah! Remove the power distributor, the distributor by the multimeter to measure two terminals corresponding to two lines of blow, found suspicious, the grounding terminal of the power distributor and the power input terminal is actually turned on (FIG. 3), and power input terminal from the battery power supply line is introduced in the positive column (FIG. 4), and without the fuse.Is that where there has been a failure? Since the power divider module is sealed with glue, there is no absolute certainty can not easily forced open, so get the normal comparison module, normally found between the grounding terminal and the power terminal is disconnected. A closer examination, it was found that the sealant module site some cracking, the module forced open, that the inside short circuit occurred indeed been burned black (FIG. 5).
Figure 5
Solution: Replace the wire harness and seizing power distributor module, the vehicle can start smoothly, failure to completely eliminate.
Figure 6
reviewed: major cause of failure is the vehicle power distributor internal short circuit, so that main power supply line to ground input line shorting , the current increases rapidly, because there is no fuse between the lines, and the diameter of the main power supply line 2 that surpasses a lot of the fine rough grounding line, grounding line so fine blow, battery power consumption is almost do. Analysis cause an internal short-circuit power splitter, it should be before the collision, the sealing portion of the power distributor knocked out of the crack, resulting in poor sealing, the dispenser is mounted just inside the left front fender (FIG. 6), rainwater readily penetrate the internal corrosion, while the power splitter module housing side is a metal material, in direct contact with the body and cause a short circuit fault occurs that the rain is the day ldquo fault; fuse rdquo ;.
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