How to set fire to your engine or look like you know what you’re doing with car electrics
First you will need an anorak. Already got one? Fine
Ok you need a multi meter, doesn’t have to be expensive, you can pick them up easily for less than £10 and almost all you will use on it is voltage and resistance 99% of the time so you don’t need the soil tester or the garage alarm attachment if they ask. Even with resistance you will largely just be checking if you have a good earth connection i.e. near zero resistance to earth
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Ok now you need a pack of these. A pack of Acupuncture needles. I use them all the time, seriously, they’re great for stopping headaches instantly, even help migraines. You don’t know how easy it is until you try. Everything is kinky until you’ve done it a few times. £3 on Ebay for 100 of them. Start experimenting on the girlfriend

Anyway, so what are these needles for? Well for back probing as they call it. You want to get electrical contact with a cable but you don’t want to go around baring bits of wire to find some electrical contact so with your acupuncture probe you can slide the microscopic needle down the wire into the plug and get nice electrical contact without disturbing anything at all. The needle is so thin even water can’t get into the hole (which is why you don’t get blood from acupuncture needles either).

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But it’s no good at the length that it is so chop a needle down to leave a stubby bit sticking out like this and there you are, you now have your expert back probe. You can use it to enter connectors or stab into a wire if necessary with an absolute minimum of fuss. Ow! Careful with that thing
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Ok now it’s no good having your multimeter wires dangling all around with your engine running, with one hand outstretched holding it on the battery earth and the other arm half way around the engine on some other component. How are you going to read the multimeter and bear in mind that the radiator fan can start at any time, even after the ignition key is removed .... BANG oops there goes your multimeter whizzing around beating itself to death.

So you need to make your life easy and go hands free. Buy a pack of these insulated crocodile clip ended short connector leads so you can attach your multimeter to the battery earth and to your acupuncture probe without having to hold on to the lead ends. £10 from Maplins for these connector leads and worth every penny. Now you can read the multimeter screen at your leisure with both hands free and ensure you have a good, reliable contact with your connectors

Just insert your back probe like this
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Here we are looking at the voltage output on an engine temp sensor on a Bravo 1.2

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And similarly we are checking the lambda voltage readouts.
Easy now you can see what’s happening:)