oap Posted November 4, 2011 Share Posted November 4, 2011 I have two work lights on the back of my 110 which I wired in myself a few years ago. They are run direct from the battery through a relay,fuse and switch in the cab then back to the lights. Recently one of them has stoped working and I have spent a few hours tring to fix it but I am stumped as to what is wrong, hopefully its something obvious and some of the experts on here will be good enough to help me out. Its not the bulb or the switch on the lamp itself because when I change them around with the other side it works fine. I have put a volt meter on the wires to both lamps and they read the same, Switch in cab off - 0 volts Switch in cab on - 12.3 volts Engine on switch in cab on - 14.3 volts I think thats about what they should read when all is in order but yet when I plug the lamp in (that I know is working) on the left hand side I get nothing. It has me beaten anyway and any help or advice would be greatly appreciated, Quote Link to comment Share on other sites More sharing options...
Disco-Ron Posted November 4, 2011 Share Posted November 4, 2011 when you swap the wiring, do you swap the earth aswell..??? dodgy earth on the one not working perhaps..?? Quote Link to comment Share on other sites More sharing options...
Puffernutter Posted November 4, 2011 Share Posted November 4, 2011 It sounds like you have some resistance in there. It is very deceptive as "off load" it will appear fine, however, the moment you put any significamnt load on it (e.g.a lamp) the resistance will drop the voltage to virtually zero. I would retrace the wiring and check and double check all connections on both the feed and earth sides. Cheers Peter Quote Link to comment Share on other sites More sharing options...
oap Posted November 4, 2011 Author Share Posted November 4, 2011 when you swap the wiring, do you swap the earth aswell..??? dodgy earth on the one not working perhaps..?? Yes they run with two different earths, if that is the problem surely the volt meter would have not worked either on that side? When I take the probe off the earth wire it shows no volts Quote Link to comment Share on other sites More sharing options...
mmgemini Posted November 4, 2011 Share Posted November 4, 2011 If you use a multimeter and the wiring is damaged leaving only one strand. You will get the full 12 volts shewing on the meter. Try using a test lamp. Quote Link to comment Share on other sites More sharing options...
oap Posted November 4, 2011 Author Share Posted November 4, 2011 It sounds like you have some resistance in there. It is very deceptive as "off load" it will appear fine, however, the moment you put any significamnt load on it (e.g.a lamp) the resistance will drop the voltage to virtually zero. I would retrace the wiring and check and double check all connections on both the feed and earth sides. Cheers Peter Thats what I was afraid someone would suggest because I ran all the wires through a conduit and stupidly used all black wire so I wont know what is what at the other side. I bet your right though. Thanks OAP Quote Link to comment Share on other sites More sharing options...
discomikey Posted November 4, 2011 Share Posted November 4, 2011 take the light apart and look at the back of the bowl, this is common on tractor spotlights, its usually the area of contact between the bulb and bowl is rusty or something similar, clean it up, nice and shiney, reattach bulb, spray with PTFE containing oil and it should last a bit better then. Quote Link to comment Share on other sites More sharing options...
discomikey Posted November 4, 2011 Share Posted November 4, 2011 check the resistiance down the wire not the voltage. this should show your faulty wires. Quote Link to comment Share on other sites More sharing options...
oap Posted November 5, 2011 Author Share Posted November 5, 2011 check the resistiance down the wire not the voltage. this should show your faulty wires. I would do this if I knew how, I looked at any joints that I can see today but still not fixed. I plan to rip everything out and start from scratch in the morning. I have a good volt meter but I have a very basic understanding of how it all works. I will put some pics up in the morning anyway, just as a lesson on how not to wire stuff. Quote Link to comment Share on other sites More sharing options...
mmgemini Posted November 5, 2011 Share Posted November 5, 2011 I would do this if I knew how, I looked at any joints that I can see today but still not fixed. I plan to rip everything out and start from scratch in the morning. I have a good volt meter but I have a very basic understanding of how it all works. I will put some pics up in the morning anyway, just as a lesson on how not to wire stuff. That's what you do when you use a test lamp Quote Link to comment Share on other sites More sharing options...
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