Was the DSC disabled?

On low traction surfaces/low speed, the DSC needs to be turned OFF to have power sent F/R.

As far as I know, there isn't a single setting (on most dynos) that will work for any specific awd vehicle. That is because different vehicles have different means of determining how much power to transmit to each wheel or axle.

It doesn't matter about the dyno, as you say above, if you can in fact set a vehicle to a fixed 4wd configuration. In that case any awd dyno could then handle the vehicle. In the case of x-drive, the torque starts off at 40/60 front/rear, but if the vehicle senses slip, ie less traction or resistance, it will divert power from that axle to the other axle. So, if the resistance isn't balanced front rear on the awd dyno, the x-drive will essentially fight it, trying to find resistance, which it interprets as traction. That sounds like what your vehicle is doing. Don't continue operating it in that mode, because you can damage components. Presumably you could fool it by disconnecting/unplugging the transfer case actuator motor, resulting in only rwd, but I am not sure how that will work.

You can't program your vehicle to lock together the centre transfer case. What you can do is ensure that the dyno you are using can work successfully with an x-drive vehicle. It is the dyno that needs to be set up here, not the vehicle. What does the dyno operator say about previously testing BMW x-drive vehicles? Has he done it successfully?

Again, those who have previously tested x-drive vehicles on awd dynos can comment on how they did it, and what brand and model of dyno worked for them.

I don't agree. Turning off DSC still leaves you with dynamic traction control (DTC). The x-drive actuator on the transfer case reads signals from wheel speed sensors, but DSC being on or off doesn't change the operation of that actuator, so power can be sent front/rear without pushing the button.

DSC does change the thresholds for brake intervention, sure. Also, DSC control algorithms could fight the dyno settings, agreed.

Yes that's true that the DTC is always ON, regardless of DSC ON or OFF.
I tought that the X-drive computer was reacting to commands given by the DSC computer, and was not taking his own decisions because it was not physically connected to sensors.

I remember reading on a French forum a quite technical discussion on the X-drive. It was debating if the input shaft(coming from the tranny) was solidly connected to the rear output shaft. The popular belief is to think that it is solidly connected, and the front is engaged at ~40% to 100% (50/50 torque split) when needed.
But from their analysis of the diagrams and videos showing X5s and X3s in off road situation, with only one wheel at the front spinning and the 3 other wheels without motion, let them believe that there was no solid connection to the rear driveshaft, but that the clutch pack was divided in two sections that could lock the front and/or back as required.
I found that system quite interresting. I would like to read more on the control part of it, if litterature was available from BMW.

In the case of the OP, it may be one of those 'special' situation where the X-drive disconnects one drive shaft completly.
Or it may be simply a defective actuator motor. Some E90 owners had to replace those actuators because it was not engaging awd anymore.

rahulsharma20, are you sure that the x-drive engages in other conditions, like snow etc.?

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Nothing wrong with this one ,on the rollers...apart from being a bad re-map for BHP!:)
YouTube - BMW X5 3L0 D 218cv @ 241cv dyno Digiservices

Yeah, I concur with JCL, it sounds like your referring to a locking diff meaning that power is going to all 4 wheels at the same percentage. From the service manual, X-Drive is integrated with ABS/DSC. Just like the mechanical TC pre 2004, normal condition give 60/40 rear to front. If the DCS senses wheeel slippage, excessive steering yaw, or acceleration, XDrive kicks in by transferring power to the wheel(s) with the best traction, usually before a wheel is able to spin. Xdrive and DCS intervenes via braking. So if a wheel spins, Xdrive kicks a brake on to that wheel which means XDrive will transmit power to the opposite wheel.

Tubo_bimmer, the traction is always set off, which means the 4x4 and explanation yellow light is not showing on the dash.

Jcl, did u mean my vehicle starts of first with the back wheels then to the front ?, however when the 4x4 traction, lights, the red explanation and ABS light is on, then the car slips. These 3 lights only come on when I start the car on a cold morning where the weather conditions are bad. However, when I turn the car off, the lights turn of and no slip is present. I think this could happen as the car is not used to the weather conditions at first, and once adapted to the conditions, the lights turn off.

However, I just want to find out if I do not have a problem with my car in terms of the four wheel not working. As turbo_bimmer mentioned a study carried out by the French that the x5 four wheels start to all work when the conditions are slippery.

I saw a video on this on youtube where the front wheels were just engaged, then as soon as the car was on the snow surface, all the wheels started to move. (I cannot find this video anymore)
So do u mean my x5, start off with the rear wheels then the front and backwheels start to work after acceleration.

And also do you why my 4x4 traction is sometimes on as well as a red explanation mark light and ABS light as this causes the car to slip, however, when these lights are not on then the car does not slip at all.

If you have those lights ON, it is not normal. You should have your X scanned with a diagnostic tool capable of reading the BMW codes. It can be anything ranging from a ABS wheel sensor to a steering angle sensor or other things.
Start with that first, then re-test.

OP:

When you start off, all wheels are driving. Pushing the traction control button doesn't change that.

Normally, if the system is working properly, there should be no lights on the dash (after the initial start sequence when the lights go through a test cycle). This means you have all systems functioning. If you push the traction control button, the 4x4 light comes on, and you still have awd like previously, but you don't have stability control. 4x4 is a confusing light, the symbol doesn't mean what people think it means.

If the lights come on and the car starts to slip when you are driving, it is due to a fault in the traction control system. Not the drive, that keeps working, but the system that uses abs wheel speed sensors to determine slip.

There is no daily adaptation process.

If the lights are coming on in the morning in the cold, then you likely have a mechanical or electrical problem that is termperature dependent. Could be a sensor, actuator, or something similar. Get it checked out, as recommended by turbo_bimmer above.

i think it must be due to the temperature as i did have the steering angle sensor repaired and the lights did stop for a week then come back on in the morning. i then took it back to bmw, and they said they installed new software on my car and still the lights were still coming on.

i then ignored these lights, is this fine? as i already have replaced the steering angle sensor.