If you turn the ignition off but the power steering pump continues to run, draining the battery, you almost certainly have a faulty pump. This is one of the top five Mini Power Steering Pump failures.
The Mini Power Steering Pump is relatively unique in that the electronic control unit (a small electronic circuit board) is contained within the pump housing rather than being a function of the cars main computer control system (ECU).
This specific condition, the pump continuously running, is almost always caused by a short circuit of one or both of the motor drive transistors which subsequently leads to a surge of power across several other electronic components. It's not unusual to find several components visibly burnt and physically damaged by such a failure.
Age, heat and use of components which were underated (in today's standards) contribute to the failure of the motor drive transistors, MOSFETs.
The good news is that the pump can almost certainly be repaired, this could save you hundreds of pounds against the cost of a replacement from a dealer, garage or motor factor.
We specialise in the repair and reconditioning of the Mini Power Steering Pump, in fact it's all we do so you can be reassured that you have expert hands restoring your pump to like new condition.
We offer two services, one where we repair and recondition your own pump, and a second where you buy a reconditioned pump from us and have the option to send your faulty one back for cashback.