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| Tweet Topic Started: Sep 20 2015, 05:23 PM (82 Views) | |
| lochaberstainless | Sep 20 2015, 05:23 PM Post #1 |
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Hi Guys, trying to get my fizzy ready for the mot, and have encountered a problem. the bike runs fine, even with no battery. when i got the bike the battery was dead, so i replaced it. when i did, the wire with the main fuse just off the battery started smoking, got very hot, so i unplugged it. trying to find the cause for this but i'm a little confused. i have a wiring diagram that i think is correct, the one i have is for a 2rv, 3au model. mines an 88 uk model, so i'm not sure but so far the wires seem correct colours. ive found that with the key in the position 1, i have continuity from the red wire to the frame of the bike, there is no continuity with the key in the 'off' position and in the position 2. i've followed the brown wires to the indicator relay, and brake switches, etc but after that i'm not sure what to do. i could even be barking up the wrong tree. again, with key in position one, i have continuity to the frame. the bike also had every lamp blown on it, i dont know if that could also be a symptom. thanks for your time, Aidan |
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| mech73 | Sep 20 2015, 07:21 PM Post #2 |
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Fizzmeister Extrodinaire
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red should connect to brown in positions 1 and 2, definitely not earth except via bulbs and flasher unit which should have a resistance, so that's why your fuse is blowing. To find the fault, you may have to start disconnecting things one by one until the low resistance continuity to earth goes away. |
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| lochaberstainless | Sep 20 2015, 09:55 PM Post #3 |
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hi, thanks for your reply. so i should have 6v+ along the brown wires in both positions? i have all the bulbs out of the bike, and still my multimeter beeps when held between the red wire and the frame. is there a resistance i should check the flasher for? i was going by the assumption that it shouldnt beep at all unless i had a light or something switched on. the horn has also been removed. i've ordered a new battery, and complete set of bulbs and a horn. hopefully this will balance the electrics and sort itself out. i take it that in position 2 i should have headlight and tail lights on? with just the indicators and brake lights working in position 1? i'm afraid electrics arent my strong suit, i'm kind of fumbling through the wiring diagram i have, and searching through threads on here i've found some of your previous advice. i didnt know the main lighting is powered by AC for example. thanks again, Aidan |
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| mech73 | Sep 21 2015, 07:30 PM Post #4 |
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Fizzmeister Extrodinaire
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so i should have 6v+ along the brown wires in both positions? Yes that's correct i have all the bulbs out of the bike, and still my multimeter beeps when held between the red wire and the frame. is there a resistance i should check the flasher for? i was going by the assumption that it shouldnt beep at all unless i had a light or something switched on. the horn has also been removed. The meter may beep even if there's a fairly high resistance to earth eg due to the neutral bulb. So that doesn't necessarily itself indicate a fault, although it's clear there's one there. it's probably better to set the meter to ohms. You should get open circuit with the ignition off but may measure a few ohms with it on. Anything less than an ohm is probably a dead short. The flasher (assuming its a standard thermal two wire one) should have a very high resistance to earth if the indicator switch is off. If the switch is set to left or right, there will be a few ohms resistance via the bulbs. i've ordered a new battery, and complete set of bulbs and a horn. hopefully this will balance the electrics and sort itself out. Maybe but I'd be surprised, it does sound like you have a short somewhere i take it that in position 2 i should have headlight and tail lights on? with just the indicators and brake lights working in position 1? Yes although the headlamp will only work with the engine running. On the late fizzies the tail lamp and speedo lamp do work off the battery, so don't need the engine. It sounds like you're working along the right lines, I'd probably try the following steps next. Check for a resistance between brown and earth with the ign switch in position 0, 1 and 2. If a low resistance is only present in 1 or 2, then the problem is probably in the ign switch itself. if a low resistance is always present, then start disconnecting things from the loom one by one ie ign switch, flasher unit, rear brake switch, handlebar switches etc etc |
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| lochaberstainless | Sep 23 2015, 08:50 PM Post #5 |
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hi, thanks for your help and suggestions. much appreciated. i've had another explore with the multimeter. found a few bodges also, unfortunately i'm not quite sure what to do with the information i'm finding. with all bulbs out of the bike, ign switch to 1 or 2 and the resistance is 10 ohm. i do not fully trust my multimeter so i've checked the amps and its drawing 0.53 amps. i think thats about right for that resistance and voltage? i think this confirms it as a short circuit somewhere? the short does not appear to be in the ign switch, ive unplugged the yellow plug, and on the frame side red-black there is no circuit and ign switch side the same. the shorted circuit breaks when i disconnect the green plug. none of the ign switch side plug terminals conduct to the black on the yellow in any position of the switch. does this clear the ign switch of fault? the blue wire to the headight dimmer switch had been spliced and attatched to the rear lamp terminal. i've disconnected this. seems like a bad idea to me? im not sure if this will dim the rear light with the main beam or not. made no difference to short. ive disconnected the rear brake switch and the fault remains. tested the indicator circuits for voltage and i'm getting power to the front indictors correctly, but not to the rear? rear tail lamp nothing. not tested the brake lights yet as its a bit awkward and i could do with more hands haha. i'll update as soon as i find out more. thanks again, Aidan |
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| mech73 | Sep 25 2015, 08:30 PM Post #6 |
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Fizzmeister Extrodinaire
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The 10 ohm resistance could be the neutral bulb and a 3 watt bulb would draw about 0.5 amps. That shouldn't blow the fuse though, which should be rated at about 10 amps. No wire from the green pug should connect to the red in switch position 1, only the blue/white should connect in position 2 - maybe try this test again but with the white wire removed from the rectifier. The test on the yellow plug sounds ok, but it doesn't entirely show there's no fault in the switch. The rear light should get its DC voltage from the blue/white wire, not from the AC headlamp feed, so the splice sounds bad as you could have the DC and AC circuits connected. Still lost of things to test. I think the wiring diagram mentioned in your first post is the correct one |
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| lochaberstainless | Sep 30 2015, 10:15 PM Post #7 |
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Hello, A quick update. Ive found the rest of that 10 ohm to be in the coil, and in a bad connection by the fuse holder. I ran the bike again, discovered what I thought was a smoking wire caused by a short, smoke was actually coming from the rectifier. It was red hot. I'm assuming because theres no load using any power? Was getting 14v ac and 30v if I revved the engine a bit haha. I've replaced all the lamps and have some working and others it so going to work though that. No headlight yet or tail lamp or brake lights. Indicating left my indicator warning lamp works correctly but indicating right it's the neutral light and speedo illumination lamps that flash. Bad earth maybe? I passed my CBT on Saturday and bits finally came from fs1 shop in holland. Can't wait to get out on the road. Thanks, Aidan |
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| mech73 | Oct 1 2015, 06:57 AM Post #8 |
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Fizzmeister Extrodinaire
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If the rectifier is getting hot, then there is a load using some power. It shouldn't get at hot as you say, so I think there's still something wrong somewhere. This will either be the rectifier itself or there's still a low resistance down to earth most likely on the battery side of the rectifier. I'd get the rectifier itself checked. It's just a single diode which is like a one way valve for electricity. It should allow current to flow one way, but not the other. Some meters have a diode checker, but you can do it with a 1.5V battery and bulb. There should definitely be no continuity between the mounting bolt and either of the terminals. Obviously when the rectifier is fitted the connections have to be the right way round, as standard the two spade connectors are different genders to ensure this. The incorrect flashing lights in the speedo, do sound like a bad earth. Well done on the CBT hopefully you will be on the road very soon.
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hopefully you will be on the road very soon.
8:58 AM Jul 11