John is this the Vauxhall or the ISUZU unit, if its the Vauxhall it is best to send it to the pump people they need to be setup after replacing any parts and the equipment to do this is about £45,000, the Isuzu is a different matter the PCU on the back of the pump is very common for going faulty, the PCU is about £500 and the pump repairers will charge £200 to repair it,Take the control unit off the back of the pump, remove the metal cover from the control unit and you will find two nice dry joints, just solder them and apresto you have just made a nice job into a very nice job, reseal the unit and its all down hill from there, i have repaired lots with no comebacks, but i always tell customer its a repair just in case. HTH