Faulty Instrument Cluster? Trans Failsafe Mode
 

My 2002 4.4i X5 has for a few months been displaying warnings for DSC and Tyre pressure every now and then. Also the factory navigation unit has been freezing up and rebooting frequently. The other day the transmission went into fail safe mode.

I took the car to the local BMW workshop. After they plugged in the diagnosis tool it turned out that the engine water temp reading was above boiling point while the radiator outlet temp was still normal. Either way the workshop said they upgraded the software in the cluster since they couldnt diagnose properly. That didn't help anything and the transmission was still in the failsafe mode.

The workshop just said that they wanted to replace the instument cluster with a brand new one, and that that might help. I didn't have any confidence for this workshop since they seemed to have no clue how to even diagnose the problem. When I drove of with the car I notuced that all the spedometer and rev meter were dead. The temp meter would go up and down like crazy. The navigation unit also rebooted itself and went into some mode with simplified graphics.

Now the car is at another workshop that is supposed to be better. The gearbox was working perfectly fine before anything of this happend, and still does when the engine is started cold.

What do you guys think the problem can be? Is it the cluster, or something else?

Try testing the battery

Second this. As a matter of fact, if more than 5-6 years old, consider changing it out.

2nd this too

Thanks for the advice. I will have the battery checked out today.

A few weeks back in another workshop visit, the workshop managed to drain the battery completely. However they recharged it and afterwards the car was behaving exactly as it had done before.

a loss of Signal from the PTCAN bus can cause the engine temp gauge to peg full red, and can also cause the transmission failsafe message to come on. if interrogating the fault memory shows in the instrument cluster, KL15 missing, check voltage output at the ignition switch and make sure the voltage is source voltage if it is not, then you should start with replacing the Ignition switch.

another common issue that can arrise is a short in K-BUS. a quick check would be to raise the volume with the steering wheel control and see if it works, if the switch is ok, and the volume does not work, then the k-bus is shorted. A common control unit on E53 x5's would be the DSC control module. The DSC module is on the K-BUS and PTCAN BUS. Start with disconnecting the DSC module located behind the drivers side(LHD) headlamp, and see if the temperature gauge still moves around.

all these checks assume engine is in good mechanical condition. and that the Terminal Resistance is with in 60ohms

Thanks for the advice. I will have it checked out.

Just another thought. It was first after the software upgrade the cluster meeters went dead. Could the software update have made things worse?

Another observation is that the mileage clock also is frozen.

there is no such thing as a software upgrade to the instrument cluster. it is simply coding that is adapted to your ZCS code. eg. language, si settings, mileage, vin, and etc. no software actually changes. only the function of the cluster is changed based on the vehicle.

This is a late reply, but the problem was finally sorted out after almost two weeks in the workshop. The brake system hydropump was replaced, and the car became operational again.

The issue with the navigation unit remains, however googling it it appears as it is isolated to the nav computer in the back.

Sounds like a poor ground connection somewhere...