Chosen Solution
Shark 18 volt vacuum will turn on, run for one second, and then turn off. Update (04/07/2019) It’s an 18 volt hand held. Shark, model SV780_N. I thought it might be a bad switch. When I took it apart, I found the switch has a circuit board attached to it. Is this some kind of overload cutout? When I jumper across the switch(bypassing the circuit board) it will keep running, meaning the battery is good.
Paul Nowack there really is not enough information on here. It sounds like a bad battery. It may not supply the required voltage needed and may fail under a load. Let us know what exact model this is and what you have checked. Update (04/07/2019) Thanks for the updated information. Would have been great to know ahead of time :-) Post some good images of the switch PCB. Possibly some bad component on it and you should try to use a multimeter to see where the switch circuit is on that PCB. Adding images to an existing question
