XSeries-forum

X5Sport wrote: ↑Sat Mar 14, 2020 4:14 pm Assuming the sender is OK then it could be a wiring issue as in poor/dirty/broken connection at wherever it plugs in. Water ingress in the connection is a possibility - might cause a short or open circuit.

If it was working then I’m just brain dumping options at present.

Clear the code and see what comes back?

X5Sport wrote: ↑Sun Mar 15, 2020 8:34 pm The speedo is driven from that sensor and it is showing as open circuit. That will cause your speedo loss. Either the sensor is bad, or there is a wiring issue between it and the main electronics. It also drives part of the ABS and DSC hence having all three lights on.

It could be temperature related if the sensor is failing when hot (such as after brakes are used) or something else is causing the wiring to heat up and a bit of expansion is breaking a connection (such as might happen in a damp/dirty connector). It might just be water inside the loom itself giving rise the signal loss because of corrosion and a ‘dry joint’.

It is probably worth opening each wiring connection between the wheel sensor itself and where the wires come into the body and spraying them with contact cleaner. Check that all of the plug/socket contacts are clean (bright metal visible), intact and without corrosion. If the wires are bad then you’ll need a new piece.

I found this.......courtesy bavauto’s blog:

https://blog.bavauto.com/4167/x5-bmw-ab ... always-on/

fenj66 wrote: ↑Mon Mar 16, 2020 8:46 pm could you try swapping the right rear sensor with the new left one, just to rule it out

X5Sport wrote: ↑Mon Mar 16, 2020 9:01 pm I have a sneaking suspicion that without the speed data (also used to drive the speedo) the mpg gauge can’t do its calculation so fails too. IMHO there’s something wrong in that circuit, but the puzzle is why the engine needs to warm up first? Unless that’s a complete red herring.

I’ve just had a look at the wiring diagrams on Newtis (not the easiest to work through!). Depending upon the actual production month, the wheel sensor looks to route to pins 13 & 14 (up to 09/03 production) or pins 15, 20 & 33 (09\03 production onwards) of the ABS/DSC module. It is this module that drives the warning lights.

The speedo also gets its data from the ABS/DSC system (from that same wheel sensor) and that is then fed to the instrument cluster.

If swapping the sensor over makes no difference then the connectors on the ABS unit could probably do with a check too. If swapping it fixes it, problem solved

I’m not sure where the ABS/DSC module is relative to the engine but if heat really is having an effect then that suggests having a look at the front end connections on the ABS/DSC unit where the wheel sensor wires arrive. My thought process is simply heat may be showing an error up in/at the module itself, such as I suggested a bad wire, pin, or just (remotely) possibly there is a cracked joint or PCB track. I’ve seen this before as an electronics engineer and it makes fault finding a real challenge, needing use of oscilloscopes to trace the signal from sensor to circuit and then across the PCB. The system would just report a no signal condition (as it is) but that isn’t the actual problem.

henrym3 wrote: ↑Thu Mar 19, 2020 8:47 pm I always thought this was quite a common problem, after fixing/replacing the things that the diagnostics reports and still having the problem the go to place is the ABS module. Dismount and send it off for repair. Unplug, remove the screws (6 I think) Most places give a limited lifetime warranty.