Ignition Warning Light will not go out

[Guest]

I have a Valeo 70 amp Alternator which charges my batteries at 14 amps but the ignition warning light will not go out. Allthe books say that if the warning light willnot go out then either the fan belt is broken or the diodes in the alternator are defective. Neither is the case as my amp meter shows a healthy charge.Has anyone got any ideas as to where I could look to find the fault.

regards,

Colin

 

[summerwind]

A physical check of the wiring is the way to go. The light goes out because the voltage at the alternator, or other charging source, is the same as at the battery terminal ie no voltage differential (almost) = no current flow = no light.

If the wiring is touching earth (battery negative) somewhere, maybe on the engine, then you will have current flow through the lamp and it stays on.

Best of luck!

 

[HaraldS]

Looks like evrything except for the indicator lamp is working.
What to check depends on whether you have an internal regulator or an external one.

On an internal one, it will either have a lug to drive a lamp or not. Often it is named "L". This terminal will have minus potential when the alternator is no running. Turning on the ingnition, puts the other end of the charge lamp on +12V so it would light up. Once running, "L" should shift to +12V or to float state and the light should go off.

With an external regulator, this circuit which is fed from a private post on the alternator, called the stator tap. It is like the battery terminal, but behind the main diodes, with it's own smaller diode. It will go to positive (to +12V) once the alternator is running, but should otherwise be floating. If you would connect a lamp to it, and the other end to minus, it would do the invers of the standard dashboard lamp, and light up when the alternator is generating power.

Usually this wire goes to the regulator which uses it to drive the lamp circuit like in the first case. If the regulator doesn't have a lamp circuit, then you can either put a simple car relays in or forget the whole lamp. Your Amp Meter tells you a lot more anyway.

 

[vyv_cox]

I have had this problem. The indicator light did not glow brightly but was clearly on. As in your case the batteries appeared to be charging OK. After much investigation it appeared that one diode was faulty and the DC current had a ripple of AC on it. The first alternator repairer I went to was ineffective, charged me money for a check but didn't find anything. On a subsequent long motoring trip the batteries boiled. We then had the alternator fully rebuilt, the light went out and the batteries now remain cool.

 

[toad]

Disconnect the field wire (small) from the alternator or regulator if separate, turn the ignition on and if the light still glows the fault is in the ignition switch or wiring and if the light goes out the fault is in the alternator/regulator.