A while ago a friend had the same problem with his moggy minor and if I remember correctly Ivan the fault on his car was the connections on the back of the dynamo had somehow been reversed and his ignition light was permanently on until he swapped them round
It only has 2 wires though. one big fat one with a spade terminal and the small field core one. Had a few suggestions on the facebook site. including checking earth and flashing the dynamo. Im running out of things to try.
Could it be something as simple as the dynamo just needs polarising which it will do if it's come off a positive earth vehicle, which is easy enough to do. One way to check Ivan is take the cover off your regulator box and see if the contacts are burnt ? If they are then you need to polarise your dynamo but also your regulator will be caput
Why are you still using a dynamo, just change it out for an alternator. £50
I know it nice to keep them as standard as possible but an alternator has such a better consistent charging current and you get the benefit of removing the regulator box which is a pain the the ass and just another thing to give you problems.
It's so easy to do, I really would recommend doing it. It was the first thing I did when I got mine and I'm so glad I did.
Today i have flashed the dynamo, checked continuity of wires, run another earth from battery, checked ignition switch wireing and still the bloody light stays on. getting fed up with it.
Hi Stiffy, been following this saga with interest. Your OP said the dynamo was showing output on the meter. So it is working to some extent. Then you say the "charging"/ignition light was always on ever since you first got the car. Obviously you don't mean that literally, you mean it comes on when the ignition switch is turned on, and only ever goes off when the igntiion switch is turned off - yes?
You've checked or changed everything on the charging circuit and it's made no difference... well that's not entirely surprising since your original tests showed that dynamo appeared to be working anyway.
I don't have the circuit diagram to hand, and I am not familiar with this particular issue in detail, but it seems to me if the dynamo was working originally, and changing things on the dynamo circuit hasn't changed anything, then the problem was never anything to do with the dynamo. Someone mentioned the regulator may be shot, but assuming that has also been checked and the issue still remains, that suggests again that the issue is nothing to do with the dynamo or the charging circuit.
So given that, why would a light come on and off with the igntion switch? It could be bad wiring at that switch, or it could be a faulty connection, or short, within the switch. It could conceivably be a fault with the lamp itself, again some issue with the wiring to the lamp or some other wiring around the lamp that is made live when the ignition switch is turned on.
As I say, I don't have any circuit diagram to hand, but I wonder if you turned your attention to the ignition switch and the lamp you might find something - and save yourself the hassle and cost of replacing the dynamo into the bargain!
I spoke to a mate (Terry) tonight. He got me thinking. He said the dynamo needs the light on to work. Maybe the live feed is coming up from the dynamo and if its not got a live feed from the switch it wont go out. however i checked the feed and seem to remember it was all ok. im gonna have another look and failing that will remove the dynamo and regulator and will get them tested.
... will remove the dynamo and regulator and will get them tested.
Apparently contacts fused together within the regulator will cause the ignition light to stay on. Have you not yet opened the regulator ? If it's the old Lucas type I remember there's a large hoop spring catch across the whole thing, slide that off and the black metal casing lifts off to show the coils etc inside. It should be pretty clear if any of the contact points have melted together.
its a brand new regulator chris. I put the old one on and it does the same. Light does go out if i push the contact down but thats not really helpful. its something stupid i have over looked and i will get to the bottom of it.