Toyota vehicle maintenance notes 3

Fault 1

a 2005 annual Toyota Rand Road, Chak cool 4700, user response vehicle hydraulic suspension control does not work, the lift indicator flashes.


After receiving the vehicle, as a user of the test to the faults. As the indicator is flashing, the system fails. The author then connected to the suspension control failure diagnostic system for detecting, the device displays the fault code ldquo; C1751mdash; mdash; AHC pump motor current is continuously rdquo ;. After the fault code is recorded, the author tries to clear the trouble code, the result of fault codes can be cleared. After the test, AHC down switch actuating the pump, but the body moves very slowly. After about 1 min, AHC pump stops, the suspension system indicator lights. Fault detection diagnostic using a suspension control system, fault code C1751 appears again. I touch AHC pump case (FIG. 1), the pump AHC found very hot. Based on past experience in the maintenance, I suspect suspension system overload, in order to prevent damage to the AHC pump, the pump motor termination system (FIG. 2) is operated.

FIG. 2

decided to check the suspension system routine. I first suspension system checks the oil level in the reservoir, the liquid level is normal; check oily, normal color and odor. It is not within the hydraulic system into the air it? For this reason, the maintenance staff to operate the hydraulic system exhaust. While previous hydraulic system exhaust is not very thorough, but after a thorough exhaust test failure remains. Then it decided to observe the data flow in the hydraulic suspension control system, to see if can find some clues. A height control sensor to the observed data, and the value can be normal values ​​vary with the height of the vehicle body. Found continue to observe the value of the accumulator pressure problem, under normal circumstances, this value is about 10.5 MPa, while the value of the failure of this car is 6.7 MPa. The car can determine the hydraulic suspension system pressure is significantly lower, the problem should be out on the hydraulic pump. Since the AHC excessive wear of the pump, resulting in a low accumulator pressure, in order to make the suspension reach the normal height, the control unit commands the hydraulic pump continues to operate, due to overload of the hydraulic pump, the hydraulic pump motor in order to avoid damage, The control unit commands the hydraulic pump motor is stopped.

by the EPC system that inquiry to view parts, pumps and motors AHC Available separately, so only need to replace the AHC hydraulic pump can be. After replacing the AHC hydraulic pump, test troubleshooting.

Fault 2

a 2008 annual Reiz 2.5 L FAW Toyota car, car engine reflects user warning light, warning light and the VSC sliding alarm warning light is lit at the same time.

After receiving the car, I first connection failure diagnostic engine control system is detected. Device displays the fault code “P0430– efficiency of the catalyst system below the lower limit (B2).” Check the exhaust system and found no leakage phenomenon. IT-2 using a fault diagnostic apparatus for active test (A / F control), a result AFSB1S1, AFSB2S1, O2SB1S2, O2SB2S2 values ​​were normal. When viewed in the data stream active test found, O2SBIS2 about change in the value of 10 s delay, and the value changes only about O2SB2S2 time delay of 2 s, very sensitive to changes. I got a car with comparative analysis found that about 10 s Delay of normal data. As we all know, 02SB2S2 role is to monitor the efficiency of catalytic converters, if the value changes too sensitive, so the main reason for mostly low efficiency of catalytic converters B2 column. And this may be the cause of the fault and the fault code P0430 is the same. Therefore, we determined that three-way catalyst column B2 (FIG. 3) fails. After the column replacement of the catalytic converters B2, troubleshooting test.

Figure 3

Summary: For the new Toyota, when the engine control system failure, engine failure once the control unit instructs the warning lights to Liang, general VSC, TSC fault warning light will be lit simultaneously alarm, does not mean that the relevant systems are also a problem.

Fault 3

a VIOS 2006 annual 1.5 L FAW Toyota car, mounted A540E type 4-speed automatic transmission, the car dashboard to reflect the user’s O / D OFF indicator irregular flashSparkle, and it is accompanied by committing break phenomenon.

After receiving the vehicle, as determined by the user of the fault test. Connection failure of the automatic transmission control system diagnostic testing, fault code found. After I find a circuit diagram, a circuit diagram analyzed (FIG. 4), the cause of O / D OFF indicator flashes abnormally comprises O / D switch block, the wire harness is bad, O / D OFF indicator lamp, the wire harness is bad, and automatic transmission control unit not working.

Figure 4

First I O / D switch block were examined. Was measured to determine the switch is turned on normally, the harness resistance is less than 1 Ω. Due to the O / D switch is a trigger switch block, when the O / D OFF indicator is flashing, the automatic transmission control unit terminal measurement, no trigger signal, the first type of cause of the fault is rectified. Continue checking O / D OFF indicator lamp and contact condition harness. After examination, it was normal. The automatic transmission control unit controls the O / D OFF indicator grounding, when the light is flashing, the control unit while the control signal changes, so the first two possible causes were excluded. In this case, the issue unit itself only the automatic transmission control. According to the detection result, can be determined when the O / D OFFf indicator flashes O / D unit does not switch stop (FIG. 5) transmits a control signal to the automatic transmission, but the error signal is issued so that self-control unit O / D OFF indicator irregular flicker, so that the problem should be in the control unit itself.

Figure 5

Finally, after the replacement of the automatic transmission control unit, troubleshooting test.

(Hao Kedong)

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