thanks for your help guys. After a return visit to the customer who had a new truck on hire was complaining the charger wasn't working because it had tripped out the mains.carried out quick reset and chat with the customer he said he had a battery link go on the cat which knock out the charger but he hadn't notice and carried on using truck with uncharged battery for long time. ordered and fitted the pump transistor and diode and problem is now fixed. thanks again