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Wiring: Expanding the tool collection
Ron Lang - 2/1/17 at 01:56 PM

Very quick one. Need some testing equipment to help with my wiring tasks. Unfortunately it's all quite new to me and I don't know what I really need. I need to be able to diagnose issues but, on occasion, also to identify which wire is which from the loom.

Do I need a tester and a continuity checker or are these the same thing? Don't want to spend a fortune but equally I don't want to be buying a new one in 6 months.

I'll also need to start watching some YouTube videos about how to actually use these things! Currently #allthegearnoidea with regards to wiring.

Thanks,

Ron


Matt21 - 2/1/17 at 02:21 PM

A 'multi-meter' is what you are looking for.

Places like maplins, screwfix etc will sell a cheap version (like £10-20) it should do all the basics that you need it too.

It will test voltage, current, resistance.

To find which wire is which, you need a rough idea of where it goes. Then you put the probes of the meter onto each end when it is set to resistance and it should show up as a low ohm reading ie 0.1 ohms.

Or, if say you want to find which is your headlight cable. Connect one end to an earth point (any bare metal chassis part or battery negetive) and the other end to the cable you suspect is the headlight and flick the lights on, you should see ~12v appear on the display.

Measuring current, you need to put the leads inline with what you are measuring. Ie, if you want to measure how many amps your headlight is pulling, disconnect the positive power cable and connect it to one of the test leads, and the other test lead to the positive power connection on the light. The light should now light up and you'll get an amps reading on the display

Important thing to remember is getting the test leads in the right holes on the meter. One should say 'comm', this is the one that the black lead goes into. The others, one is for voltage/resistance, the other is for current. Put the red cable in which ever you need. If you get it the wrong way you can blow the fuse inside the meter (easily changed mind you).

Next thing to get right is the setting on the selection dial. For measuring resistance on most the stuff you need just select the lowest ohm setting. Not sure what the voltage one selections are but the lowest one that is above 12v is the one you want for car stuff.

Hopefully that's of some use to you


mcerd1 - 2/1/17 at 02:36 PM

^^^ what he said, a fairly cheap multi-meter should do everything you need it too - but get a digital one not an analogue one

I've got a bog std. machine mart one that's lasted me more than 10 years now and still going strong
and an even cheaper draper branded automotive one that came free with something else that's just as good...
(automotive ones have a couple of extra features, like reading engine revs etc...)



[Edited on 2/1/2017 by mcerd1]


steve m - 2/1/17 at 02:36 PM

Matt ^^^ has got it spot on, and as he says, small multi meters cost £10 ish, but depending on how far you want to go, can cost an awful lot more

just a couple of leads with a bulb attached is also a good thing to have, assuming theres power getting through!

Heres on on ebay that I would get to start, infact I may get one, just to add to the kit cars toolkit !

New Accurate DIGITAL LCD VOLTMETER MULTIMETER WIDE RANGE TESTER AMMETER AC DC UK

steve


miskit - 2/1/17 at 02:54 PM

I have a couple, the SF LAP one is OK. http://www.screwfix.com/p/lap-mas830b-digital-multimeter-600v/75337

Most useful function is "beep on continuity" which means that when the two things you are testing (two ends of a lead for example) are connected the unit beeps so you know without having to be looking at the screen.

Be very careful when testing current that you
a) don't test a direct short from the +ve bat terminal to earth (flash, bang and a new fuse - if there is one..)
b) remember to switch the leads back - or the next time you test for voltage .. see a)


mcramsay - 2/1/17 at 03:42 PM

I bought one of these https://www.ebay.co.uk/itm/160753828712, best £17 I have ever spent when it comes to wiring. Clip it on the battery and then when you touch the probe on a cable/ terminal it will tell if it has 12v or an earth. You can then inject a 12v or earth into that cable. Really good for wiring in new looms as for example you can inject 12v on to the lighting circuit and see if things light up prior to connecting up to the switches. You can get the same result jerry rigging leads from the battery but this is much safer. I will take this tool to any car wiring specific task.


garyo - 2/1/17 at 04:30 PM

I second the 'beep continuity' function. So much easier when running through multiplug pins trying to find a wire.


David Jenkins - 2/1/17 at 04:48 PM

Try and get a multimeter with optional crocodile clips as well as the usual probes - it's useful to be able to latch one lead while poking around with the other.


britishtrident - 2/1/17 at 09:41 PM

For a budget meter it is best buying something known -- Uni-T are a good budget brand the UT203 is a good model low cost but features a DC amp clamp. For only a little more there is the Owon B35T with multiple extra function and a 20 amp maxiumum on the amps scale most cheaper meters are fused at only 10amps.

For tracing wires and find breaks the best tool is wire tracker.


owelly - 3/1/17 at 12:55 AM

I have a cheapy digital multi-meter (actually I bought four for £2:50 each from Screwfix sale!!) which I keep in my toolbox for 'everyday use'. The leads are cheap crap and break easy so I pre-tape the ends before they break!! These meters tick all of the boxes apart from looking for a pulsed signal. For this sort of work I have a large analogue meter which came from Maplins. It was half price at £9.99.


nick205 - 3/1/17 at 09:09 AM

Machine Mart "Clarke" multi-meter does me for such things.

ETA...similar to this one http://www.clarkeintern ational.com/shop/product/details/digital-multimeter-8-function-cdm35c/path/multimeters-tachometers

[Edited on 3/1/17 by nick205]