R Surrey Posted July 29, 2016 Report Share Posted July 29, 2016 My TR4 has been converted to negative earth and fitted with Alternator. Problem is when start engine, ignition warning light does not go out and ammeter shows slight discharge until I rev engine to 2000rpm. At this point warning light goes out and ammeter shows charging in progress. As soon as I take foot off accelerator and revs drop down warning light comes back on etc. So when car is idling there is a discharge showing on ammeter. I have changed alternator to see if this was faulty but got same result. Any thoughts would be appreciated. Quote Link to post Share on other sites
dpb Posted July 29, 2016 Report Share Posted July 29, 2016 Hi Is that you in Laxey? Apologies if not. If it is, I can lend a hand if you like.. Could be a slipping belt? Dave ==== Quote Link to post Share on other sites
RogerH Posted July 29, 2016 Report Share Posted July 29, 2016 (edited) Hi, welcome to the forum. What is your name? did the problem happen immediately after fitting the Alternator.? If so then recheck all the wiring - especially any earth wires. If it has happened sometime after fitting the alt then either the battery or Alt have gone duff. Check the voltage on the battery - 12.7V if lower than this you may have a dead cell. This could then load the alt causing the Ig light to stay on. Roger Edited July 29, 2016 by RogerH Quote Link to post Share on other sites
peejay4A Posted July 29, 2016 Report Share Posted July 29, 2016 Which alternator do you have fitted? Is it a two terminal or three terminal type? Some alternators (eg some Denso ones) need an ignition fed exciter supply and if it's missing you could see your symptoms. Quote Link to post Share on other sites
Lebro Posted July 29, 2016 Report Share Posted July 29, 2016 +1, but: Most alternators need a feed to get started - usually supplied from ign sw, through the ign warning lamp, then to the field circuit of the alternator. But once the alternator has started producing it's own voltage, that will then take over, (the warning lamp goes off. cos it's got 12V on both sides) & dropping to tickover would not normally stop it from producing some charge. Bob. Quote Link to post Share on other sites
peejay4A Posted July 29, 2016 Report Share Posted July 29, 2016 My Denso doesn't work that way Bob but I agree that most others do. Quote Link to post Share on other sites
R Surrey Posted July 29, 2016 Author Report Share Posted July 29, 2016 Which alternator do you have fitted? Is it a two terminal or three terminal type? Some alternators (eg some Denso ones) need an ignition fed exciter supply and if it's missing you could see your symptoms. Hi,thanks for reply. Wiring harness has 2 cables (one large spade connector and one small.) Alternator has three connectors (two large one small). The large spade connector fits either of these without any difference to output to warning light. Maybe this is where exciter needs to go? Quote Link to post Share on other sites
R Surrey Posted July 29, 2016 Author Report Share Posted July 29, 2016 Hi Is that you in Laxey? Apologies if not. If it is, I can lend a hand if you like.. Could be a slipping belt? Dave ==== Hi Dave, yes it is Dick in Laxey. Checked belt and that's not it. Will digest replies and get back to you.Thanks Quote Link to post Share on other sites
R Surrey Posted July 29, 2016 Author Report Share Posted July 29, 2016 Hi, welcome to the forum. What is your name? did the problem happen immediately after fitting the Alternator.? If so then recheck all the wiring - especially any earth wires. If it has happened sometime after fitting the alt then either the battery or Alt have gone duff. Check the voltage on the battery - 12.7V if lower than this you may have a dead cell. This could then load the alt causing the Ig light to stay on. Roger Hi Roger, my name is Dick, apologies re my lack of IT skills. Have had my TR since 1984 and managed to overcome most issues but electrics is not one of my strong points. Yes the problem has been there ever since changed the polarity so maybe it is something to do with this exciter cable that I don't have fitted. Quote Link to post Share on other sites
R Surrey Posted July 29, 2016 Author Report Share Posted July 29, 2016 +1, but: Most alternators need a feed to get started - usually supplied from ign sw, through the ign warning lamp, then to the field circuit of the alternator. But once the alternator has started producing it's own voltage, that will then take over, (the warning lamp goes off. cos it's got 12V on both sides) & dropping to tickover would not normally stop it from producing some charge. Bob. Hi Bob Thanks for response, I'll have a look at this as sounds most likely problem, Regards Dick Quote Link to post Share on other sites
peejay4A Posted July 29, 2016 Report Share Posted July 29, 2016 Dick. You have a two terminal alternator that works as Bob has described. When the Dynamo was removed was the wiring at the black control box altered? Quote Link to post Share on other sites
R Surrey Posted July 30, 2016 Author Report Share Posted July 30, 2016 Pete, the change to neg earth was done by Auto electric outfit and I didn't see what they did. Control box was removed and cables associated with this are now cocooned in tape so difficult to see which cables were jointed. Did go back to the company with the problem but there response was that I had a lazy alternator and suggested I change it which I did but without any difference. Went back to auto electrics but really just got fobbed off. I,ve put up with it for long time but really need to sort it out. Thanks Quote Link to post Share on other sites
peejay4A Posted July 30, 2016 Report Share Posted July 30, 2016 Is your warning lamp a normal filament bulb or is it an led? Quote Link to post Share on other sites
Lebro Posted July 30, 2016 Report Share Posted July 30, 2016 My TR4 has been converted to negative earth and fitted with Alternator. Problem is when start engine, ignition warning light does not go out and ammeter shows slight discharge until I rev engine to 2000rpm. At this point warning light goes out and ammeter shows charging in progress. As soon as I take foot off accelerator and revs drop down warning light comes back on etc. So when car is idling there is a discharge showing on ammeter. I have changed alternator to see if this was faulty but got same result. Any thoughts would be appreciated. From the description above once you have rev'd the engine the light goes out, & you get a charge. Once this has happened the alternator will supply it's own field current, so the type of bulb is no longer an issue. The odd part is that the light comes back on again at tickover - it shouldn't. Bob. Bob Quote Link to post Share on other sites
peejay4A Posted July 30, 2016 Report Share Posted July 30, 2016 I guess the small rectifier pack that supplies field excitation could be duff. Quote Link to post Share on other sites
RobH Posted July 30, 2016 Report Share Posted July 30, 2016 Pete - since Dick says he has swapped the alternator for another he would be very unlucky to have two duff units surely? Just about the only thing left then is the speed the alternator is rotating at. If it isn't turning fast enough at idle to generate enough volts, it would do this. ( I guess thats why Dave asked about the slipping belt). Dick - what alternator is it and what diameter pulley has it got? Have you had the narrow-belt conversion done with a new narrow pulley fitted to the crank or are you still using the original wide belt? Quote Link to post Share on other sites
peejay4A Posted July 30, 2016 Report Share Posted July 30, 2016 Oh yes, silly me. Quote Link to post Share on other sites
graeme Posted July 30, 2016 Report Share Posted July 30, 2016 Pete - since Dick says he has swapped the alternator for another he would be very unlucky to have two duff units surely? Unless the regulator/rectifier is separate as in the 15AC alternator. Hi Dick, Good to see you on the Forum, remember me, I bought your old dismantled TR4. You may be interested it is know it is complete and road worthy. Cheers Graeme Quote Link to post Share on other sites
R Surrey Posted July 30, 2016 Author Report Share Posted July 30, 2016 Hi Pete. When changed to alternator fitted a narrow pulley and thin belt. Was running with Lucas 36A alternator but part of answer from auto electrics when I went back to them was to say fit more powerful alternator so have a Lucas 45A fitted at moment. Have also recently changed fan belt and re tensioned it just in case this was problem. Today I tried exciter cable fix that has been mentioned. I ran a cable from terminal of ignition warning lamp and connected that directly to alternator via the spare large spade connector. However all that did was light up the ignition warning light without putting ignition switch on. I was going to change this cable to the smaller spade connector but need to get a double connector to do this. I will try this tomorrow hopefully it won't do any damage to alternator. Thanks Dick Quote Link to post Share on other sites
R Surrey Posted July 30, 2016 Author Report Share Posted July 30, 2016 Unless the regulator/rectifier is separate as in the 15AC alternator. Hi Dick, Good to see you on the Forum, remember me, I bought your old dismantled TR4. You may be interested it is know it is complete and road worthy. CIMG4029.JPG Cheers Graeme Hi Graeme, of course I remember you and the TR looks great, well done. Was reminded of you just last week as I was loading up a transit having sold all my other spares as a job lot. Am in the process of downsizing and don't have the space in our new place hence they had to go. My 4 is still going strong where as I'm falling apart ( I go for a hip replacement next month) and will have to make a decision about what do with it. Would find it hard to part with after 36 yrs of ownership. Regards Dick Quote Link to post Share on other sites
peejay4A Posted July 30, 2016 Report Share Posted July 30, 2016 Dick, do you have a multimeter? Can you measure the voltage on the small wire at the alternator end with the wire disconnected and with the ignition on, motor not running. Then reconnect it, start up and measure the voltage at the same point at idle then revved up a bit. You might need to poke a paper clip into the spade connector to connect the meter. It would be useful to know what the warning light/exciter circuit is doing. It'll also be useful to see what the battery voltage is doing under the same conditions. Quote Link to post Share on other sites
Lebro Posted July 30, 2016 Report Share Posted July 30, 2016 Hi Pete. When changed to alternator fitted a narrow pulley and thin belt. Was running with Lucas 36A alternator but part of answer from auto electrics when I went back to them was to say fit more powerful alternator so have a Lucas 45A fitted at moment. Have also recently changed fan belt and re tensioned it just in case this was problem. Today I tried exciter cable fix that has been mentioned. I ran a cable from terminal of ignition warning lamp and connected that directly to alternator via the spare large spade connector. However all that did was light up the ignition warning light without putting ignition switch on. I was going to change this cable to the smaller spade connector but need to get a double connector to do this. I will try this tomorrow hopefully it won't do any damage to alternator. Thanks Dick The two large terminals on the alternator are connected to the same place internally, & are the main output, normally only one of these is used. The smaller terminal is the one which needs a supply from the ignition circuit - normally via the ign warning lamp. Bob. Quote Link to post Share on other sites
dpb Posted August 1, 2016 Report Share Posted August 1, 2016 Hi Dick If you like I can drive my TR4A over, and we can compare and contrast the wiring if you like? Dave ==== Quote Link to post Share on other sites
R Surrey Posted August 1, 2016 Author Report Share Posted August 1, 2016 Pete/Bob/Dave, Today ran cable from warning light to small terminal on alternator as per the excitor thoughts but no difference at all. Tomorrow I will use the multimeter to check readings as per Pete's thoughts. Interestingly I found the paper work from when I did the Alternator conversion. This was a purchase from Moss, the installation instructions are mainly about fitting of pulleys etc. Then it goes on to say chose alternator & loom. The alternator that I got was the 36amp but I did not get a loom for whatever reason. The loom part number was quoted as TTK3020LB and have looked that up today. This shows a Block terminal containing three wires fitting to the alternator ie two brown wires one going to each of the large spade connectors and a brown/yellow cable going to small spade connector. The two brown wires then run as part of a loom and terminate together in a ring connector. The single cable B/Y terminates in a female spade connection. Not sure of the significance of this. Unfortunately this component shows as out of stock/back order. Any thoughts on this. Dave I will get back to you about comparing cabling. Car is presently in garage at holiday cottage and have people in there so need to arrange this.Thanks Dick Quote Link to post Share on other sites
R Surrey Posted August 3, 2016 Author Report Share Posted August 3, 2016 Pete Did as you suggested with multimeter with following results Small connector removed from alternator and then ignition switched on gave reading of 11.7v. Reconnected terminal, started engine and sat in tickover, reading was 1.3v, revved the engine and very little change in reading (best was about 5v) until reached 2000rev and then reading jumped between 11.7 and 13.2v with warning light going out and ammeter showing charge situation. Return to tickover and voltage dropped to as before ie about 1.3v with warning light back on and no charge to ammeter. Seems to be the 1.3v is the problem but what can cause this ?Regards Dick Quote Link to post Share on other sites
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