what does 'check the signals' mean? you want to find out which wire is which? you want to find out if the senders work? you need to clarify what you're trying to do
an ohmmeter will track the connections, although I'd expect the harness to have some sort of labels .... to find out what's happening on each wire, you'll have to start by knowing what's supposed to happen, electric gauges mostly have variable resistance senders so you'll need the engine running to check their function
Bill
