Appears as a network fault to ECU. No data from ECU. When key turned on all warning lights come on. When key turned to start engine the engine starts and runs normally. The warning lights remain on. Obvious electrical items all checked and appear OK. Problem started in very snowy weather and then a lot of rain.After being in the workshop over last weekend I’m told the dashboard lights now go off when ignition starts but the warning lights come back on after less than 5 minutes. Now suspected to be due to damp but where to start!
If this happened after a rain it sounds like you may have water ingress. I would check for water leaks around the w/s. Check the connectors and modules under the dash for water or the greenish corrosion. You will have unplug the connectors. Hope this helps.
Try disconnecting the battery and reconnecting it. Make sure it is decently charged, these cars are extremely fussy over their battery. If it’s weak you will run into electrical problems. The cold weather can discharge or damage the battery very quickly, but it will still be able to start the car, you’ll just have faults start happening.
Once you’ve done that, Hold down the trip computer mode button and turn the igntition on. It should enter a diagnostics menu where you press the trip button and it will go through various things like bulb test, sensor data and other things. Can you toggle through the diagnostics menu?