JST Posted February 12, 2007 Share Posted February 12, 2007 those that know me will know that electrics and me dont go together they are not my strong point!!! (neither is much else but staying with electrics for now!) Did some nice wading today and post wading the alternator light didnt come on and the alt was not charging. removed it, stripped it down cleaned and dried it out and put back together. now the a good 14V at the batteries (as much as it ever was) with engine running so charging no problem however the alt light still doesn't come on with position II until i turn the engine off then it comes on briefly then goes out again. its all reconnected the same as it was before. so is this a problem? i guess the light is out when the ignition is put on as there is 12V+ there and the light comes on Temporarily when the engines turned off as the 12V is cut but then comes back again extingusihing the light? does this mean i have a constant 12+V feed to through the system and it will drain the batteries? any thoughts? Quote Link to comment Share on other sites More sharing options...
Orange Posted February 12, 2007 Share Posted February 12, 2007 As far as I've worked out... Ignition on - battery light comes on to let you know the alt isn't charging Engine running - battery light off, unless the alt is faulty engine off again, with ign on - battery light on cos the alt isn't charging anymore I think that is the way it should be, but if it's not I'll go and change the way the wife's one was wired up on Saturday afternoon!! HTH Adrian Quote Link to comment Share on other sites More sharing options...
JST Posted February 12, 2007 Author Share Posted February 12, 2007 Adrian - yep thats what it should do, mine doesn't though it does this: Ignition on - no light Engine running - no light but charging engine off again, with ign on - light comes on then flickers off. Quote Link to comment Share on other sites More sharing options...
ciderman Posted February 12, 2007 Share Posted February 12, 2007 One side of the warning light is connected to your battery+ the other side comes from the alternator warning light , The alternator warning switches polarity from - Earth (when not running/charging ) to + pos when every thing is running fine hence the light goes out + and + means no circuit so light goes out . If you catch my drift Quote Link to comment Share on other sites More sharing options...
Orange Posted February 12, 2007 Share Posted February 12, 2007 Ooooohhh!! Flashy lights!! Can't help with what might be wrong in that case, I just know how it should be! If you weren't getting the flashing light, I'd say the bulb had blown (ask how I know that!!! Astra dashboards are a right bu##er to get back!!), but that's thrown that argument out of the window! Quote Link to comment Share on other sites More sharing options...
JST Posted February 12, 2007 Author Share Posted February 12, 2007 Jase so that means that the alt wng light is +ve rather than earthed i guess all the time less immediately after switching off, so less the fact the light doesn't work is this a problem? Quote Link to comment Share on other sites More sharing options...
pugwash Posted February 12, 2007 Share Posted February 12, 2007 i think the upshot is that you buggered up the wiring gee you only had to undo 2 bolts- that makes you more incapable than me!!!! Quote Link to comment Share on other sites More sharing options...
ciderman Posted February 12, 2007 Share Posted February 12, 2007 Yes there are no perm. earths to the warning light , the alternator does the earthing bit . Quote Link to comment Share on other sites More sharing options...
ciderman Posted February 12, 2007 Share Posted February 12, 2007 Blimey Jim that pooch is gettin big Quote Link to comment Share on other sites More sharing options...
pugwash Posted February 12, 2007 Share Posted February 12, 2007 hey jase well you know i'm not exactly small but have a look at this one: Quote Link to comment Share on other sites More sharing options...
JST Posted February 12, 2007 Author Share Posted February 12, 2007 Oiii, stop going OT i need to know if the alt is usable as it is? anyone? Quote Link to comment Share on other sites More sharing options...
steve_a Posted February 12, 2007 Share Posted February 12, 2007 if no light on when turned to II then you don't have circuit for the excitor voltage. The brush may be stuck in on that one or poor contact on the running surface. it sounds like the brush is only making contact while spinning to me, which means it working but not quite as you would prefer it. Always a chance that the diode pack has gone, but i think you'd expect runaway voltage when revving which you probably checked. Quote Link to comment Share on other sites More sharing options...
Shaun D Posted February 12, 2007 Share Posted February 12, 2007 Couple of questions:- What make of alternator is it? if you know that is. Have you tried connecting the warning light wire to earth at the alternator and confirming that the warning light and ignition circuit are ok. Did you strip the alternator to bits to clean it, if you have I think you may have wired it up incorrectly internally, it's the only way I think you could get these symptoms. Let me know what the answers are and if necessary I'll take the back off one of my old units (got about a wheelbarrow full )and check. HTH Shaun Quote Link to comment Share on other sites More sharing options...
JST Posted February 12, 2007 Author Share Posted February 12, 2007 Steve a - brushes are OK and i cleaned the contact surfaces, which bit is the diode pack? the black box on the back that connect to one of the three connectors on the alt with a short wire? can you get replacements of just the diode pack. whats runnaway voltage? i revved it with a voltmeter across the battery and it went up to expect 14 and a bit that was about it. Shaun - dont know the make, the sticker has come off! i believe its a disco 120A one though. will try connecting the wng lamp wire to earth instead of the alt and see what that does. i didnt strip it just took the plastic cover off the back and dried,cleaned out the brushes,contact. so no internal wires removed. so problem seems to be the earth from the alt to the wng lamp when on position II from either dodgy brush connection or faulty diode? Quote Link to comment Share on other sites More sharing options...
white90 Posted February 12, 2007 Share Posted February 12, 2007 never had a a moments trouble even after extreme wading I aim the hose into the rear of it when the engines is running so far no trouble (fingers crossed) unlike the Horn wires that had met Mr angle Grinder I discovered after: dismantling Fuse box , steering column shroud/removed horns/removed new wing Quote Link to comment Share on other sites More sharing options...
ciderman Posted February 12, 2007 Share Posted February 12, 2007 Jim is that cod and chips in the dogs bowl? Sorry James . Quote Link to comment Share on other sites More sharing options...
steve_a Posted February 12, 2007 Share Posted February 12, 2007 runaway voltage - the voltage regulation goes to pot and you get >14v out (like 16v upwards) If you had the brushes out and checked them then not sure - land rover law dictates that you could have got it apart checked it, put it back together and it got stuck or something a few moments later. From my limited alt knowledge, if you are getting 14v then the alt has been excited, the excitor current makes the charge lamp glow, so no lamp means no current which means no 14v.... if the bulb is blown the no excitor current, so no 14v So i guess it starts to look like brush only contacting while alt turning (possible, most things are on a landy!) or problem with the diode pack. Hopefully Si Brown will bimble along, his knowledge is far better than mine on these things. Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted February 13, 2007 Share Posted February 13, 2007 Even if the exitor is duff, an old altenator will self exite with residual magnetism. The light probably comes on when you kill the engine as no ignition feed, but the altenator is still spinning...that charge then lights the warning bulb for as long as it takes the engine to come to a complete stop. I have a similar problem on my series...the momentum in the electric fan will continue to run the ignition for a few seconds after killing it. My guess is the exitor circuit has died somehow...check all connections etc... Quote Link to comment Share on other sites More sharing options...
simonb Posted February 13, 2007 Share Posted February 13, 2007 Right then chaps, i've just tested wot the 90 does it and it goes like this. 1) Engine off 2) turn key to postion 2, charge light comes on 3) Start engine, light goes off. 4) Stop engine by key to posn 1, light remains off 5) Stall engine with key is posn 2, light comes on Measure volts with engine off and then with it running, if the 2nd measurement gives you 14v or better (with headlights and blower on) alt is charging ok. If light goes off (eventually) with engine off you are ok. To be sure connect ammeter to one or other of the battery terminals and measure amps range. You should have zero ideally or possibly up to 0.005A if you have an alarm/immobiliser. If the diode pack has gone it will flatten the battery overnight and you will have several amps flowing with the engine off. Black /silver thing which slides out of the back of a Lucas or Marelli Magnetti (45, 55 or 65A) alternator which a short (usually yellow wire) from inside the alternator connects to, is the combined brush/regulator assembly. Diode pack is inside the alternator and is more involved to remove. It usually has to be unsoldered from the output winding. The really isn't anyway you can connect an alternator up the wrong way.... Quote Link to comment Share on other sites More sharing options...
SiWhite Posted February 13, 2007 Share Posted February 13, 2007 James, Have you checked the exciter wire onto a good earth? Or do you get no light on at anytime? I had a similar prob with my alt, turned out to be a fatigued soldered joint on the exciter wire. Check the exciter circuit against a good earth - if the light comes on when in contact with earth and goes out when not as expected, I'd suspect something inside the alt. Start with a replacement diode if available, as they're cheaper than a new alt. PS I'd also check the earth between the alt and the block. I had problems a while ago and ran a good earth from the alt bolt to the chassis as a guarantee that the earth wasn't a problem. Won't hurt to do the same on yours..........? Quote Link to comment Share on other sites More sharing options...
JST Posted February 13, 2007 Author Share Posted February 13, 2007 cheers for the advice guys, things deteriorated today, now no light and no 14V either. time for a replacement me thinks, luckily Walfy is coming to the rescue next week. wng light wiring is good, in that if i earth the end the light comes on. so conclude that the diodes/exciter bit are kaputh Quote Link to comment Share on other sites More sharing options...
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