GolfGTIforum.co.uk
General => Car audio => Topic started by: vin297 on 26 November 2007, 10:40
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Im gonna try to install a kenwood stereo into my mk3 golf. i understand i need to swap the live and ignition live wires. Can someone help me on how to use a multimeter. i have just purchased one but havent a clue on how to use it.
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Pretty open question,
What do you want to do with it?
What purpose have you bought it for?
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With the multimeter, set the wheel on it to 20v range !!
Then put the black probe onto something that will be your earth like the door hinge and hold it on it then with the red probe touch it on the terminals and what ever terminal you touch and get a reading above 10v that is your permanent live.
Then turn the igintion on and do the same and a different terminal shouls now get a reading as well as the previous one and this will be your ignition live !!
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Perm live should be read and ignition live should be yellow. Earth should be black. These were standard colours introduced for car headunits back in the late 80's.
If you have a new headunit these colours should all match up. In fact it should have the correct connectors in a Golf MKIII but no doubt someone in the past has hacked off the ISO plug. If you want the stereo to NOT go off with the ignition wire the permenant live to bothe the red and the yellow of the headunit.
Nick
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With the multimeter, set the wheel on it to 20v range !!
Then put the black probe onto something that will be your earth like the door hinge and hold it on it then with the red probe touch it on the terminals and what ever terminal you touch and get a reading above 10v that is your permanent live.
Then turn the igintion on and do the same and a different terminal shouls now get a reading as well as the previous one and this will be your ignition live !!
Make sure its on the DC range, but 20v is the best one as above. DC should have a straight line with a dashed line underneath it, AC is the one witht he wavy line.
Switch it on to Ohms range (Omega symbol), any will do.
Put the two probes ends touching
you should get a reading of about 0.1 ohms, thats normal. This check makes sure that the probes are working correctly first before you start measuring anything.
Then as said above, always put the black one on first and always take it off last. Trust me, it will take far too long to explain why :wink:
The new HU should have come with a loom to connect it to the existing car wiring. Have a look at it and there will be approx 13 wires from memory, the two you are interested in are the Red and the Orange. If you look closely at these wires there will be bullet connectors on both these wires, a male and a female. Disconnect both at thiese bullet connectors and swap them over, you will end up with a wire that starts off red and ends up orange and a wire thats opposite to this.
Connect it all up, job done. 15 mins start to finish including programming radio stations is about all it will take, seriously.
Never under any circumstances read the instructions, its a man thing :grin:
This link might help for the future:
http://www.doctronics.co.uk/meter.htm
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Then as said above, always put the black one on first and always take it off last. Trust me, it will take far too long to explain why :wink:
I don't trust anyone - tell us why.
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I don't trust anyone - tell us why.
If you don't know then you dont need to. Google?
Heres another link that might help with using a MM (google that while you're there)
http://www.umd.umich.edu/casl/natsci/slc/slconline/IDIG/Current.swf
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I am well aware of how to use a multi-meter, thanks. And that last link was dealing with current measurement, and therefore totally irrelevant to the above.
The polarity or order of the probes when testing voltage (or current, or resistance) with a multi-meter is of no consequence whatsoever, I just wondered why you thought it was.
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I am well aware of how to use a multi-meter, thanks. And that last link was dealing with current measurement, and therefore totally irrelevant to the above.
The polarity or order of the probes when testing voltage (or current, or resistance) with a multi-meter is of no consequence whatsoever, I just wondered why you thought it was.
The link was aimed at the person who started this link and therefore relevant to them.
If you know as much as you say you would know that it does in fact make a difference. :wink:
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The link was aimed at the person who started this link and therefore relevant to them.
If you know as much as you say you would know that it does in fact make a difference. :wink:
Well, you've got me there - I give in. Now will you tell us?
And for what it's worth, I'd use a test light for simple 12v feed identification. :smiley:
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OK, it applies more to higher Voltages more than lower ones but can be considered best practice.
When you attach the black lead first to the earth point then earth is effectively felt at the tip of the red lead, so if you touch it by accident you are touching earth or very close to earth i.e low volts. If you connect red first, in this case to a high voltage source (I used to deal with up to 1500V DC) you get the same, that voltage is effectively at the end of the black probe. All it needs is for you to complete the circuit and accidently touch the black probe and through your body you; complete the circuit, you give the volts a lovely big resistor to be dropped across and short a big wadge of current via your body (heart!!) to earth and you wake up with a crowd round you. If you wake up that is :cry:
I'd use a bulb as well if no MM available. :wink:
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Being that a voltmeter in principle is itself an extremely high resistance, it's debatable as to weather or not there would be enough current flowing to pose a risk of electrocution, but if I were testing 1500v dc, I probably wouldn't want to find out. Measuring current at those sorts of voltages would certainly require some care, else you'd probably look something like this .> :laugh:
Unless looking for a specific voltage, I always choose a bulb or testlight when checking 12v feeds, as applying a small load (even 5w) gives a more reliable result. I've been left scratching my head before when a DMM has told me that I have a solid 12v, only for it to disappear when it is loaded.