Dave64 Posted December 16, 2017 Share Posted December 16, 2017 Hi, All. General purpose query on wiring of alternator on project vehicle. Alternator is stamped "Baxters" with code NAB 301. Looking up the site tells me it is either a rebuilt Lucas 12v 65amp, or Baxters own build for Australian content. I have a matched pair of 80mm VDO electronic Speedo and Tacho gauges, the speedo is no problem as it is an electronic drive direct out of the transmission, pretty straight forward. With the tacho, the "pulse" terminal , should be the "W" terminal according to what I read. Some of the wiring loom is missing, the main alternator "out" wire (heavy brown) has a large eyelet which looks like it goes to either the starter motor or a terminal block somewhere or other. There is provision for a push in plug in the centre of the back of the housing which I don't have, has multiple spades on it, I would imagine it would have both a positive "in" terminal as well as an "indicator (idiot light) terminal as well. I have access to a Haymes workshop manual , which although is pretty handy, doesn't really give a clear indication of the actual wiring for this 12L engine. Can anyone direct me to either a clear wiring diagram to suit a Discovery 1992 w/TDI 200 that would pertain to this particular engine? I can't really take a great deal of notice of what I have here as I only have the bare minimum wiring on the engine itself. Glow plugs, fuel shut off, oil pressure sender, water temp sender (I intend replacing the latter two with mechanical gauges) and starter motor , both main in cable as well as solenoid activation terminal. Any chop out would be greatly appreciated, thanks. Dave64 Quote Link to comment Share on other sites More sharing options...
western Posted December 16, 2017 Share Posted December 16, 2017 200tdi wiring info diagram below, as standard the alternator should have big terminal for the main output to battery via starter solenoid WL or ind terminal for the dash no charge light & possibly a 'W' stud or spade terminal to drive a rev counter. hopefully my 2 diagrams will help, IIRC if there is no W terminal, you can attach a wire the one of the stator bolts to obtain the signal -- BUT check tht with a auto electrics supplier before doing it. Quote Link to comment Share on other sites More sharing options...
Dave64 Posted December 17, 2017 Author Share Posted December 17, 2017 Western, Think I got it, will attach two photos, one with what wires I have hooked up, unsure of just where one goes, other photo with wires removed. Large thick brown, obviously main current feed FROM alt TO post on starter motor (thence to battery?). There IS a post marked "W", you can just make it out in the photos, has a white wire/grey trace, so take it that is the tacho out terminal.Both these have terminals held on with nuts. The other one I'm not sure of the position of, brown/yellow trace has a push on female spade. Again going by the photo there is a male spade sitting just above the main alt out terminal, but also there is a recess in the centre of the rear of the alternator which has TWO large male spades and one small male spade on top of them. This recess has a wire retaining spring to obviously hold some sort of push on connector which I don't have at all. Going by the two diagrams you posted, mine seems to be a combination of euro connecters AND stud connections. Who knows what that may mean, wouldn't surprise me that it could have been changed over at some stage, have a feeling that this is a replacement alternator for the original. Often find that when it comes to local components they can and often do throw in a curly one. Hence the brown/yellow wire, can't find it on the Haynes wiring diagram I have here. Thanks again, Dave64 Quote Link to comment Share on other sites More sharing options...
David Sparkes Posted December 17, 2017 Share Posted December 17, 2017 Yes, I think you are correct, the alternator is equipped to dual standards. The thick brown wire connected to the stud is the main output from the alternator. The brown yellow wire is connected to the IND terminal, and should therefore go back to the ignition warning light. The two unused large male lucar terminals beneath the brown/yellow lead are alternative main output terminals. As you are using the better connection, the stud, I suggest slipping a short length of heat shrink over both the large lucars. The white wire attached to a stud; the casing seems to be marked W, so that stud is the signal feed to the tachometer. I think that has covered all your points. Regards. Quote Link to comment Share on other sites More sharing options...
western Posted December 17, 2017 Share Posted December 17, 2017 Is the stud where your thick brown cable is attached marked with a ident ? can't make out a marking in your photo Quote Link to comment Share on other sites More sharing options...
Dave64 Posted December 17, 2017 Author Share Posted December 17, 2017 Thanks, Guys. The thick brown wire and the white/grey wire have two different size eyelets on them, maybe 1/8" and 1/4", so can't really get them mixed. Only the white/grey is marked, "W", no other markings around HOWEVER, there are TWO possible places the "ind" wire, yellow/brown female spade can hook up. As I wrote earlier here, there is a single male spade in a recess by itself ABOVE the main brown ALT out terminal, ALSO where the two large lucar recess is, another possible male spade in there (as in photos), just not too sure which one should be utilised as NEITHER is marked, "ind" or otherwise. Suppose easiest thing to do is wait until the engine is started and hook a low power lamp/holder to other end of it (in series) and see what happens? Reckon it will either work (light up) or not, probably can't really do much damage? Had the alternator tested and bearings checked, all OK, asked the bloke to mark the posts/outlets, but he dropped it off at a local workshop without doing so. Thanks again, Dave64 Quote Link to comment Share on other sites More sharing options...
western Posted December 17, 2017 Share Posted December 17, 2017 the 3 spade terminals in the recess are or should be the same as the left diagram on the 2nd attachment above, so small is for charge warning light & the 2 large can be combined into 1 connection, found this diagram which looks to tally up with your alternator & connections https://lotusmarques.com/info/technical/29-general/1153-lucas-12v-65a-alternator-engineering-drawings-and-dimensions it shows a + next to the stud at your thick brown wire, W at your white/grey wire & ind at your brown/yellow wire. the single spade terminal above the stud your connected to, shows as AUX on the diagram below. Quote Link to comment Share on other sites More sharing options...
Dave64 Posted December 17, 2017 Author Share Posted December 17, 2017 Many thanks Guys, will go with that Lotus diagram. Cheers, Dave64 Quote Link to comment Share on other sites More sharing options...
western Posted December 17, 2017 Share Posted December 17, 2017 happy to help. Quote Link to comment Share on other sites More sharing options...
Dave64 Posted December 30, 2017 Author Share Posted December 30, 2017 Ginning around with a bit of wiring on this Lucas 65amp alternator, if I put a 12volt hit into the 'ind' post, alternator kicks in up to 14.8 volt, so assume that it needs to be excited to produce charge. Soon as the engine stops, drops back to 12.2 volt at battery. This is. probably normal, so how would I go wiring a small value. 12v idiot light in series and leave it live whilst ever the battery is connected, been shutting the engine down by pulling the spade off the fuel solenoid, then taking the battery terminal off. Wiring still a bit of a rats nest with bare engine in chassis, no cab or body yet. Dave64 Quote Link to comment Share on other sites More sharing options...
western Posted December 30, 2017 Share Posted December 30, 2017 the IND stud needs to go to the brown/yellow wire which is the charge light on the dash panel, voltage will self excite to 14 volts when engine is started/running and will drop off to 0 when ignition is off, if the ign is on but engine not running the volts will show battery volts = 12 volts. i would get the cab/dash fitted with the instrument pack then finish off the wiring. Quote Link to comment Share on other sites More sharing options...
Ex Member Posted December 30, 2017 Share Posted December 30, 2017 The "normal" indicator circuit... Power from ignition switch => Dash Light => Diode => Alternator. In parallel to the light is a resistor. The attached is from the 300TDI era manual. Quote Link to comment Share on other sites More sharing options...
Dave64 Posted December 30, 2017 Author Share Posted December 30, 2017 Thanks Men Dave64 Quote Link to comment Share on other sites More sharing options...
Dave64 Posted January 1, 2018 Author Share Posted January 1, 2018 OK, just so I have this perfectly clear, the diode (G126) blocks any current running back along the "ind" wire to the ignition? The resistor (G101) is there simply to carry some current in case the idiot light blows? So, the answer to my next question would now be self evident, NOT a good idea to run the engine for too long without some current going to the "ind" post on the back of the alternator? And, looks like the idiot light is wired in series, in one side, out the other? Hope I got that right, Cheers, Dave64 Quote Link to comment Share on other sites More sharing options...
Ex Member Posted January 2, 2018 Share Posted January 2, 2018 Yes, those are the reasons for the diode and resistor. Without the diode, the alternator can power the switched components and under certain conditions prevent the engine turning off. Without power to the ind lead, the alternator will not turn on and charge. Yes, power to one side of the light, other to the alternator. When the alternator is not charging the ind terminal goes to ground and the light turns on. In addition, if the rectifier fails, you will get AC voltage at the ind lead and the light will flicker. Quote Link to comment Share on other sites More sharing options...
Dave64 Posted January 2, 2018 Author Share Posted January 2, 2018 Great, thanks Red90. Dave64 Quote Link to comment Share on other sites More sharing options...
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