water temp' sender query

[midge]

Hi there, can someone please confirm which temperature sender unit out of the two on the t/c heads, is the one for the gauge, the red or the black ? many thanks.
midge.

[Guy Croft]

I suggest you test them, then publish here with photos because a lot of people ask this and I'd have to test them myself to answer anyhow..

Clamp in a vice and attach an ohmmeter (usually on a multimeter from Halfords etc) to the body and the spade terminal and heat each up with say, a lighter or small butane torch.
The warning switch sender will go straight to zero resistance at about 95 deg C, the gauge sender will show progressively decreasing resistance as it heats up.

GC

[SteveNZ]

It would be easy to check. The overtemp switch should be open circuit when cold. The temperature gauge sender would have some resistance.

[midge]

Many thanks to both Guy and Steve for your replies, they both sound like logical tests for these senders, which look very similar save for the colour of the insulators.