a 2007 Buick LaCrosse annual Shanghai GM cars, ECO 2.4 L engine mounted, matching 4T45E automatic transmission, the user reflect the car 4 of the power window lifter does not work sometimes.
After receiving the vehicle, the user first author repair faults verified and found four electric window lifter can be properly controlled by the switch and a respective set of switch control, the user does not reflect the occurrence of the fault. Because users reflect the car’s fault is sporadic fault, for such occasional failures, sometimes the most time-consuming maintenance and energy, so only until a failure occurs it is more convenient to tease out the maintenance process to determine the specific fault location. Repeated test did not test the user’s fault repair after repair because there are other vehicles in the car parked in the factory for about 2 h.
FIG 1
In view of the failure of the vehicle is sporadic failure, maintenance experience combined with the author of the vehicle power window system, caused by the initial determination I the reason for failure may involve vehicle harness connector or relay virtual connection, or the control switch actuator intermittent failures. So I tidied according to pre Maintenance ideas on the car for a simple investigation. Considering the possibility of a failure of four switches or actuators at the same time is extremely small, thus eliminating a second possible cause of the failure. Then they also harness plugs were examined and found no signs of water or virtual connection corrosion. But sets control switch (FIG. 1) in the driver side door of the car disassembly inspection found that some viscous substance in the gap switch. I suspect user cola beverages spilled on the switch, resulting in the occurrence of power window lifter intermittent fault, so the replacement of the driving side power window control switch assembly. After the test, fault has not appeared, the car will be temporarily delivered to users.
Day 2 due to the same fault Depot car. I took the test found that, different from the 1st into the plant, the plant into the vehicle with a failure, the power window switch on the four doors have no control over the lifter. Because there is a clear failure symptoms, it is easy to repair the vehicle. The author sets control switch driver side door is removed, with a circuit diagram, were measured in the wire harness without breaking the connection to the harness. It was found by measuring, with a pin J1-4 voltage 12 V, turn up, press down on the current driving side of the glass lift control switch, A front passenger side lifter, left rear and right rear door window regulator window lifter button corresponding J1-5 and J1-6, J1-2 and J1-3, J1-9 and J1-10 and J1-11 and J1-12 are pin 12 V output voltage, current control switch does not prove a problem. Measuring the driving side door trim respective harness connector P303 are 12V output voltage during switch operation, and no change in the harness while shaking, show P303 \ J303 connector virtual connection does not exist phenomenon. The author then decides to open the driver’s door trim measure whether there is a normal motor end voltage is present. The interior trim panel apart, the test harness reconnect found, but at this time the switch control lifter work, and no matter what operation the switch can normally controls each glass door lifter. You are not just plug harness connector virtual access it? But before measurements and found no signs of virtual access, so I decided to J1 and P303 \ J303 plug disconnected again view the connection status pin. After careful examination and found no abnormalities.
FIG. 2
try holding the attitude of each stitch processing, the test repeated several times, the switch can still be normal glass lifter control. Given the car’s fault intermittent fault, and because they are the 2nd depot repair, so I recommend that you leave your car factory a few more tests to determine whether the fault is actually removed, users agreed. Day 1 test is normal, a second test is still continuing normal day, this has been ruled out that the fault, then the driver’s side door is refitted trim. But when all vehicle recovery, test failure. In order to find a breakthrough, the author again driving the door trim side door open, the motor harness connector find the carefully observed, a total of five line connector on the motor (FIG. 2), three thin lines, two thick line, and circuit diagram is very different. The vehicle end of the motor only two conventional contact wires (FIG. 3), is directly controlled by the switch. After inspection and measurement found that thin wires are connected with two switches on the motor, and with no other lead wire harness, there is a collection of the other three harnesses connected to the BCM J1-20, two additional thick line should be achieved and the motor lift down function of the circuit.
Figure 3
Figure 4
Now a circuit diagram of the discovery service manual, a circuit diagram of a car LaCrosse 3.0 L (FIG. 4) with the same vehicle wiring. The car has a rapid rise and fall glass function, and has a glass rear lock the car automatically rise function. Further, when the power window except on the remaining three sides of the door drive switch is open the outer door of the driver-side current control switch is still possible to control the other three door glass lifter. The measuring window lifter three control lines found in the glass rise automatically function after executing up, down or lock the car, have the correct output voltage, but no corresponding lifter operation, thus demonstrating that this fine 3 line is a signal line, the other two lines of the window regulator motor power line and a ground line, and power is normally ground and normally rise and fall to achieve the lifter function is achieved by the internal motor control module. This indicates that even when not actuated window regulator switch, measured with a multimeter red line should have a voltage 12 V, the ground should be measured as often ground. Green measured with a multimeter found ground line to ground resistance, the resistance value is 1.2 Omega ;, normal. No red line voltage measurement, should normal power supply voltage. So far, the cause of the fault can be determined lifter motor does not work for the operating voltage.
Figure 5
found that the carefully measured, and the driver side door pillar of the vehicle body A vehicle body side corresponding connector plug remains without power. Finding a circuit diagram of the known system, the power window lifter 25 A is a circuit breaker control. Then open the fuse box on the right side of the instrument panel, found in the two rear surface of the circuit breaker 25 A (FIG. 5), wherein when one attempts to unplug the power supply voltage measuring circuit breakers no end. Main battery power fuse 2 (FIG. 6) on the blown fuse box to check the engine compartment. After installing a new fuse, the power supply voltage measurement. Installed after the circuit breaker, actuating the power window control switch set, glass lifter to work properly. But ready to reset the circuit breaker was found, it has been hot, it seems that the line should be a problem. Will disconnect the circuit breaker, measured across the resistor to ground circuit breaker infinity end, the other end of the ground resistance can be concluded that the presence of 2 Omega ;, line-to-ground short circuit. Because of thisThe rear portion of the harness connecting the circuit breaker and has more trim cover, if disassembly intuitive, large and time-consuming work, so I decided to disconnect the harness connector of one investigation method. The harness connector J301 four doors connected to the vehicle body, J302, J351 and J352 is disconnected after the test, the circuit breaker is no longer generate heat, it can be concluded due to the presence of the wire harness in the door of a short to ground fault. Will then reconnect the disconnected harness connectors, each connected to a harness connector after a period of residence shorting touch whether heat, when the right rear door and the wiring harness is connected to the circuit breaker again heat J352, it is possible to determine the presence of the right rear door harness short to ground in place. They then removed the right rear door trim, window regulator motors found harness has been worn in contact with skin and metal gate. Closer examination reveals that the reason this happens is because the glass elevator to the wrong wiring harness, the harness lead to interference with the elevator cable, causing the right rear door glass lifter work in crowded cable harness cable and metal doors between, a long time will cause the insulation on the wiring harness worn in contact with the metal door. When the manipulation of the right rear door power window switch that the lifter work, resulting in overheating open the circuit breaker, so that any manipulation of the door also appeared power window switch are inoperative phenomenon. After a cooling period circuit breaker recovery lifter can work properly. Due to line failure, when the power window switch is often manipulated, causing lifter work frequent contact breakers, disconnect, because the circuit breaker Prolonged heat adhesions, causing the engine compartment fuse blown.
6
re-bandaged in the damaged wiring harness and wiring harness to the correct layout, and replace the fuse and circuit breaker, repeatedly test troubleshooting .
Summary: After the car’s maintenance records review found that the car had done the right rear door of sheet metal spray paint, and replace the right rear door glass lifter. Since the maintenance personnel when changing the sheet metal lifter is arranged a wire harness to an error, resulting in an insulating sheath wire harness is worn lifter cable extrusion. Although the fault has been ruled out of the car, but this is due to human failure causes together. This reminds us that in the maintenance replacement parts, be sure to remember clearly the right parts to the installation location and layout of the wiring harness, if not remember, please refer to the repair manual. With the increasing number of new models, each model will have a lot of different configurations (such as LaCrosse driver side power window control switch set there are three models), which resulted in the same vehicle there is not the same components, harness and control. When servicing these vehicles would require the majority of employees in the maintenance of vehicle maintenance, vehicle must be configured to understand, and targeted development of maintenance programs, in order to avoid unnecessary detours at fault repair work.
(In the spring-Paul)