He is talking sh*t.


More likely to have blown a fuse as said above or another earth wire
elsewhere on the car.


As an aside, I dont think most patrol men are "clued up".

I used to work for a company that supplied RAC with diagnostics testers.
They had a RED and BLACK wires for connection to the vehicle battery
and labels on the coloured wires saying positive/negative.,
Nearly had 50% of them returned for damage caused by connecting them
up backwards.

Thick cnuts