Paul J Posted October 10, 2017 Report Share Posted October 10, 2017 Help required from an electrical guru please. I have fitted a denso kubota alternator all went well with the exception of the the ignition warning light not working, I have earthed the lamp holder and the light works but it's getting no control from the alternator. The alternator connections are P, Ig, L. B is to D on my regulator. P has been left vacant, Ig is to a switched supply on the coil and L is connected to the warning light, not sure what I'm doing wrong here. I have also converted an old regulator as a junction A1 -A fused to D, light wires joining at F. Thanks Paul Quote Link to post Share on other sites
peejay4A Posted October 10, 2017 Report Share Posted October 10, 2017 So one side of the warning lamp is connected to the L terminal in the alternator. Where does the other side of the warning lamp connect to? It needs to go to another switched live. On the Lucas ACR alternators the initial field excitation comes from the warning lamp but on the Denso there is a switched live to the Ig terminal which does this. The warning light terminal swings from earth (engine stationary) which lights the lamp, then to +12v when charging so the lamp goes out as there's 0v across it. Quote Link to post Share on other sites
Paul J Posted October 10, 2017 Author Report Share Posted October 10, 2017 So one side of the warning lamp is connected to the L terminal in the alternator. Where does the other side of the warning lamp connect to? It needs to go to another switched live. On the Lucas ACR alternators the initial field excitation comes from the warning lamp but on the Denso there is a switched live to the Ig terminal which does this. The warning light terminal swings from earth (engine stationary) which lights the lamp, then to +12v when charging so the lamp goes out as there's 0v across it. Hi Pete Yes At the lamp holder I have for some reason two switched live wires a white one and a brown and yellow from the L terminal on the alternator, I have a switched live to the Ig alt also. My problem seems to be that I'm no getting the Earth at the lamp with ignition on and engine stopped. The power from alternator lamp brown yell diminishes with the revs to nothing which I assume is correct. The lamp worked fine with the Dynamo, perhaps the white wire to the lamp needs a different source. Quote Link to post Share on other sites
Paul J Posted October 10, 2017 Author Report Share Posted October 10, 2017 Hi Pete Yes At the lamp holder I have for some reason two switched live wires a white one and a brown and yellow from the L terminal on the alternator, I have a switched live to the Ig alt also. My problem seems to be that I'm no getting the Earth at the lamp with ignition on and engine stopped. The power from alternator lamp brown yell diminishes with the revs to nothing which I assume is correct. The lamp worked fine with the Dynamo, perhaps the white wire to the lamp needs a different source. I have just removed the bulb holder and have 12.45 volts from the alt lamp wire with ignition on no engine, connecting the bulb to the wire and to earth no light. The bulb does work when testing on battery. I'm now confused. Quote Link to post Share on other sites
peejay4A Posted October 10, 2017 Report Share Posted October 10, 2017 (edited) This is how I have mine connected. Its a Denso but not a Kubota.Heavy brown/yellow from the alternator goes to the modified control box where it's connected to the brown/white plain brown and brown/blue wires that were there before but are now commoned together.Light gauge brown/green is connected to the Lamp terminal on the alternator and at the control box is connected separately to the brown/yellow that goes to the dashboard lamp. If you've joined all the small wires together and this is one of them then the lamp won't work. Finally there's an ignition controlled live feed to the Ig terminal at the alternator - a new wire. Edited October 10, 2017 by peejay4A Quote Link to post Share on other sites
RogerH Posted October 10, 2017 Report Share Posted October 10, 2017 Hi Paul, is this any help https://www.google.co.uk/search?q=denso+kubota+alternator+wiring&tbm=isch&source=iu&pf=m&ictx=1&fir=kkZjEUVSnxEqFM%253A%252ClejgJxSJW0A7BM%252C_&usg=__tNT69L5CpllhuPpSpZ6CNJ4kZmM%3D&sa=X&ved=0ahUKEwi1_Iz5kObWAhWhJMAKHdBpC5cQ9QEIKDAA#imgrc=VWGSFPBHM0UFdM: Roger Quote Link to post Share on other sites
Paul J Posted October 10, 2017 Author Report Share Posted October 10, 2017 Well bit of a struggle this afternoon two under 5s to look after, just caught them with a hose pipe full flow into the kitchen, thank heavens for CBeebies. Here's a rough sketch of what I've done. This should explain my situation better. Tried that link Roger and connected alternator output to starter solenoid and charged ok but no ampmeter, not sure about the ignition light. Thanks Paul Quote Link to post Share on other sites
peejay4A Posted October 10, 2017 Report Share Posted October 10, 2017 (edited) I cant see where the battery and ammeter are in your diagram so unable to advise why your ammeter isnt working but try this. Take the wires off the E and F terminals on the control box and connect the wires together. That connects the alternator L connection directly to the warning lamp which should have switched 12v on the other side. Connected as you have shown it looks like theres 12v on both sides of the warning lamp so it cannot light. Also there shouldn't be full 12v on the L output, itll probably be OK - I hope. Sorry for the missing apostrophes. IOS11 will not let me edit them in. Edited October 10, 2017 by peejay4A Quote Link to post Share on other sites
Paul J Posted October 10, 2017 Author Report Share Posted October 10, 2017 Pete all else ie ammeter battery etc I have left as the normal Dynamo set up, I have disconnected E & F, with the engine running I have 0.075 Volts coming from the alternator but 13.5 volts from the lamp wire E. I suppose it's not a huge problem as all else is fine, the ammeter is working fine with the output connected to D. Probably something quite obvious but at the moment I can't see it. Paul Quote Link to post Share on other sites
peejay4A Posted October 10, 2017 Report Share Posted October 10, 2017 OK and what happens if you connect the two wires as I suggested? Quote Link to post Share on other sites
Paul J Posted October 10, 2017 Author Report Share Posted October 10, 2017 OK and what happens if you connect the two wires as I suggested? No light Pete Quote Link to post Share on other sites
peejay4A Posted October 10, 2017 Report Share Posted October 10, 2017 Doesn’t sound good. If you weren’t almost at Lands End I’d be round there with my Fluke. Quote Link to post Share on other sites
Paul J Posted October 10, 2017 Author Report Share Posted October 10, 2017 Yes it's a fair drive to the far West. I'll buy you a pasty! I feel my problem is the 0.075 volts from the alt L terminal at idle, by adding an earth to the lamp wire the bulb will light but not controlled by the alt. Another compromise. Paul Quote Link to post Share on other sites
RobH Posted October 10, 2017 Report Share Posted October 10, 2017 Can we just make sure of what you have told us Paul ? You seem to say that the wire from L on the alternator is brown/yellow and that the voltage on it is 12v static and 0v running. That would imply that the bulb should connect from L to earth rather than to supply. Is it a standard bulb or an LED? If the latter you will need to swap polarity for it to light. Quote Link to post Share on other sites
Paul J Posted October 10, 2017 Author Report Share Posted October 10, 2017 (edited) Hi Rob The wire from Alt L is brown/green with ignition on no engine 12.5 volts, engine running 0.075 volts. Wire from the lamp is brown/yellow is a switched 12volt. The two wires join at the regulator. By F and E terminal which I have joined. Standard bulb fitted. Thanks Paul Edited October 10, 2017 by Paul J Quote Link to post Share on other sites
RobH Posted October 10, 2017 Report Share Posted October 10, 2017 So it from that it would seem that particular alternator requires the lamp wired from L to earth. If it was as you have it now, the light would be on when the alternator was providing charge. Quote Link to post Share on other sites
Paul J Posted October 10, 2017 Author Report Share Posted October 10, 2017 So it from that it would seem that particular alternator requires the lamp wired from L to earth. If it was as you have it now, the light would be on when the alternator was providing charge. Yes I would have thought there should be no voltage from L with ignition on before starting the engine, the lamp would be on, with engine running it seems right with 0.075 volts which would put the light out. I can live without the light as the ammeter is functioning correctly, I will only miss it when switching on ignition, the alternator is charging at idle. Thanks Paul Quote Link to post Share on other sites
graeme Posted October 11, 2017 Report Share Posted October 11, 2017 Paul, I have the same problem on my TR4A. The alternator has been on for over 10 years now and is so reliable (compared to Lucas), I am not concerned by the missing light. Perhaps if it does fail the light will come on? Cheers Graeme Quote Link to post Share on other sites
peejay4A Posted October 11, 2017 Report Share Posted October 11, 2017 Googling seems to show that there are quite a few people in the kit car space using these alternators and having the same problem. Weird that because I've had two, a copy and a genuine Denso and they both work fine. Quote Link to post Share on other sites
Paul J Posted October 11, 2017 Author Report Share Posted October 11, 2017 Well we live and learn I suppose. Strange Graham but it's kind of comforting that I'm not alone with no ign light. This is a genuine Nippon Denso Pete but perhaps designed when working to show a charging light. What really puzzles me is at the ignition lamp with ignition on I have 12.5 volts from the L wire on the alternator, using the lamp bulb from the L wire to earth the bulb will not work. The White switched wire from the ignition switch to the ign lamp also shows 12.5 volts, using the lamp bulb to earth from this wire and the bulb lights. How can that be 12.5 volts the same is it to do with amperage. Another electrickery problem. Thanks all Paul Quote Link to post Share on other sites
stuart Posted October 11, 2017 Report Share Posted October 11, 2017 You can have 12 volts but with very little amperage it wont light a bulb which is why its better to try and find wiring faults with a bulb and two bits of wire rather than an expensive meter. Stuart. Quote Link to post Share on other sites
peejay4A Posted October 11, 2017 Report Share Posted October 11, 2017 +1 Quote Link to post Share on other sites
RobH Posted October 11, 2017 Report Share Posted October 11, 2017 It might be that this particular unit is designed to drive a low-current indicator like an LED, rather than a standard bulb. Quote Link to post Share on other sites
Paul J Posted October 11, 2017 Author Report Share Posted October 11, 2017 It might be that this particular unit is designed to drive a low-current indicator like an LED, rather than a standard bulb. Ok Rob would there be a suitable LED type that would suit the ign bulb holder. Everything else is just fine. Quote Link to post Share on other sites
RobH Posted October 11, 2017 Report Share Posted October 11, 2017 I guess its a screw-type MES holder Paul (?) - so something like this perhaps: https://www.autoelectricsupplies.co.uk/product/1381/category/119 Quote Link to post Share on other sites
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