Symptom: a Mercedes-Benz S320 sedan traveled 21,000 km, the car electric windows sometimes can not lift. The owners describe the vehicle electric windows often do not work.
Diagnosis: test the car, not fault. Connect with MB Star C3 to diagnosis, it shows network system failure. According to electric windows system control principle can known, the car electric windows is control by CAN- BUS, then diagnosis the CAN- BUS system, but the test results were normal. For this reason, the maintenance staff asked in detail about the situation of the car when fault occurs. According to the driver to reflect the car failure was more frequent, and always appears during driving, but does not appear when parking. For a long road test, use Mercedes Benz MB Compact3 test the CAN-H and CAN-L waveforms, has serious clutter, but electric window system able to work properly. This is occasional failures, mostly due to the line poor contact. Collated the CAN data bus, not found unusual. Then again to check the electric control unit harness of four doors, found right rear door electronic control unit connector rear CAN-H line (orange / green) is close circuit.
Troubleshooting: after handling the harness test the car, electric windows work back to normal. After two weeks, the fault does not occur again. So far, troubleshooting.
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