Thread: Engine low oil light. Change it to a pressure gauge, any one done it?

Originally Posted by sierrafery

You know wrong... that's a simple pressure switch normally closed to earth which opens under pressure, while it's closed it completes the warning lamp's earth path hence the lamp is on then when pressure opens it the lamp goes out... the alternator has nothing to do with this also as PhilipA said the black wire is futile cos the switch is earthed via fixing... if you have a white(with green trace) wire hanging from the alternator you have to connect it back where it belongs cos it's the alternator's protection.

EDIT: @Tombie was faster

A pressure switch. That makes sense, not sure where I got voltage from. Thanks.

Thanks for your replies , its made the job clearer, at least I know what I'm looking for now. Appreciate it. cheers.