briggs engine wiring

[sarti]

I installed an electric start Briggs 122037-0550 engine on our Agrifab lawn vac, but there is a grey wire with white connector coming out of the engine
does anyone know if this is an AC lighting wire or a DC battery charging wire I hooked up my fluke meter to it and it reads on the ac or dc scale..I can't seem to find this info anywhere...thanks