BMW Z4 E89 - hard top does not open or close

With the above-mentioned vehicle type, the electrically retractable hard top may stop or fail completely during the opening or closing process. The error memory may have entries stored for individual micro switches in the hard top area. If no definite faults are found in the hydraulic pump, actuator cylinders, relays or micro switches during the diagnosis, special attention should be paid to the harness in the hinge areas of the hard top. Repeated bending stress causes individual cables to break, which in turn interrupts the power supply and signal transmission of the position sensors.

In order to carry out troubleshooting, the harness of the micro switches of the electrically retractable hardtop should be exposed in the hinge areas and, by exerting slight tension, checked for broken cables, damaged insulation or the build-up of verdigris. If several cables are already broken, it may be advisable to replace the entire harness so as to prevent another failure. In such a case, all cables are replaced and the risk of overlooking a damaged cable, which could lead to another failure later on, is significantly reduced. However, if only individual cables, for example one or two, are affected and all other cables are still visually and electrically intact, repairing of just the damaged sections may be sufficient. This means that the hard top can be made functional again with an easily manageable amount of effort, particularly if the vehicle needs to be closed up again quite quickly.

Once the cause of the fault has been rectified, delete the error memory and then carry out a test drive.

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