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Chery Eastar sedan central locking Fault Example

Failure phenomenon: a 2003 annual Chery Eastar sedan, mileage 180 000 km. Say users, the car will automatically latch in the control and then unlock.

BRIEF

Check Analysis: Symptom first confirmed as a user of the vehicle is determined. This may cause malfunction of the central locking switch causes include fault, short circuits, and a body control module BCM internal fault related wiring. Use X431 fault diagnostic examination, the body control module BCM trouble code storage, fault diagnostic functions using the actuator operation test is performed, the central locking and the lock can be unlocked during normal operation test. If the remote control unlocking, the door automatically latch the fault does not occur, indicating that the point of failure is not a remote control system wherein the control system. The author of the original circuit diagram of a central locking painted line connection diagram (reference), for further examination of the central locking opening, the locking signal line, found in the control latch signal line (left front armrest control switch connector pin No. 2) existence has been to turn on the phenomenon, the wire harness in the left front door of the A15 pin connector a (indoor wiring harness to the left front door harness connector) was destined PE4 / A5 pin of BCM. Try disconnecting the left front door harness connector A, the blocking signal in the control line to ground short circuit disappears, indicating a fault in the range PE4 / A5 between the connector pins of BCM A. Connected connector A, then disconnect the BCM connector PE4 and found the short circuit disappears, so my analysis is BCM internal fault, but the fault persists after replacing the BCM.

Now that the circuit diagram, the left front door control switch (bars), the left front door latching switch key, right front door control switch (bars), right front door latch key switch belongs to a parallel state, when the left front door OFF the right front door of the control switch and switch control, central locking opening and closing again, find fault no longer occurs. When replacing the left front of the control switch, the normal use of the vehicle, but replace the right front door control switch, the fault occurs again.

Solution: Replace the right front door of the control switch assembly, failure to completely eliminate.

Review Summary: In the troubleshooting process, measuring the left front door armrests control switch connector No. 2 feet for grounding, I believe that the line is shorted to ground, so quite a few detours, causing MisdiagnosisOff. But after normal vehicle measurements, we found that when the locking or unlocking BCM receives a signal and performs the corresponding operation, since the program line key belonging to the locking switches switch, then the key lock off switch will remain just grounding signal until receiving BCM and after performing the unlocking operation signal, the latching switch by the latch key signal often just grounding into a floating state, and the unlock signal is often converted to the Ground signal cycle so forth. Manufacturer has to provide a signal to the terminal metal design BCM unlocking or locking, BCM is able to bind to the left, the right front door key switch positions of the door contact switch and whether a change in status to determine whether the door is open illegal, if it is illegal to open, will trigger the alarm system. I hope everyone later in the repair process, encountered a similar situation, do not think that has been provided to the BCM Ground signal when locking or unlocking is the point of failure.

(Solution Akihiro)

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