Checking electrical connection

[Hairdye]

Hi and Happy New Year
Im trying to sort out a problem with my auxillary heater. However a diagnosic  is showing a problem with the circulating pump.
I'm not very electricaly minded but I put the ignition on and tried a tester between earth and then one wire at a time . Tried both wires and nothing lit the tester up . Am I doing right ? Should it have shown live at the wiring or am I doing something wrong. I don't want to spend 100 pound and it's not the pump but an issue elsewhere in the wiring .
Thanks

[Smeeagain]

As I see it, you now have three separate posts running on this topic, although one was undee the topic of using the scanning tool. You have this post here and two in the general section. Adding a new post isnt going to suddenly get you an answer if you didnt get the answer in a previous post. And splitting the information over different posts only dilutes the number of responses. Keep it focussed and stick to the one post.

[Hairdye]

Sorry guys.
My original post was about the scanning tool  but then in that postI was told to check to see if the webasto worked  first. Fault codes showed circulation pump and combustion air fan. I had a few good helpful replies to that post. However I thought it was easier asking about the electrical testing under another heading rather than confusing my other post. Lesson learnt for the future.
Thanks

[Smeeagain]

it's not a problem, but I think your second post in the general section will cover it