JimHepburn Posted February 5, 2010 Share Posted February 5, 2010 I have no stereo loom in my 300tdi 90. I'm pretty rubish at electrics so need to know the best place to pick the live up from. I want to be able to have the stereo on with in ingnition off. Just to complecate matters, i have an earth cut off switch. Can i run an earth direct from the battery to the head unit in order to stop me losing my presets. Thanks in advance Jim. Quote Link to comment Share on other sites More sharing options...
western Posted February 5, 2010 Share Posted February 5, 2010 Earth it normally & feed it 12v via the purple wire or direct from the battery, most units have wiring info with them, if not try a search using your units makers name/model number or look on the makers website Quote Link to comment Share on other sites More sharing options...
BogMonster Posted February 5, 2010 Share Posted February 5, 2010 If you want it on with the ignition off, and there is no harness in the vehicle, get some twin core cable (you can buy it from places like Vehicle Wiring Products) this has black and red cores in an overall black outer sheath, and run it back to the battery with a fuse on the positive side right next to the battery. Quote Link to comment Share on other sites More sharing options...
gilloverland Posted February 6, 2010 Share Posted February 6, 2010 Just a thought - if the main vehicle has an earth cut off switch (presumably for security)and you give the radio its own 'unswitched' earth... if someone tried to start it or you forgot about the switch wouldn't 400 amps try going through the radio!!! Quote Link to comment Share on other sites More sharing options...
western Posted February 6, 2010 Share Posted February 6, 2010 add a fuse to the radio's Earth & power wires, if the above did happen only the fuse would blow & do it's job of protecting the radio. Quote Link to comment Share on other sites More sharing options...
JimHepburn Posted February 6, 2010 Author Share Posted February 6, 2010 Thanks for the advice. Having time today with a 12v test light and the advice given, this is the conclusion i have come to. The stereo has a switched live (for the main power) which i will take off the back of the switched live from the ingnition barrel with an inline 20amp fuse. As i have a earth cut off, i will run a separate earth from the battery direct to the unit. "Western" says this needs a fuse in case i start it with the switch off. What size should it be? I also need to have a perminate live to keep all the presets. I think i need to run this direct from the battery, does this alsao needs a fuse? To some people these may sound like silly questions but i find elecrics really difficult. Thanks Jim. Quote Link to comment Share on other sites More sharing options...
western Posted February 6, 2010 Share Posted February 6, 2010 in my ham radios both power & earth wires have a 15amp fuse fitted, your radios handbok should tell you what size fuse to fit in the power wire, put the same in earth wire too. Quote Link to comment Share on other sites More sharing options...
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