ignition light on when it shouldnt be?

[ronmidg]

the ignition light is on very faint all the time, (but full on when it should be), it is brighter if something is switched on like wipers or lights (but not full on), the brightness varies as the wipers change direction, put a new battery in at the weekend for a different reason, and the ign light behaviour is exactly the same. There is an extra light on the dash which comes on when the key is turned backwards and glows in sympathy with the ign light when its doing its thing. The van was originally a bus, then a camper, then back to a bus aqain, needless to say the wiring is not original.

What do the leccy experts think? I suspect a not very good earth somewhere under the dash, but I'm not an expert and would appreciate a spot of advice before I go digging, please?

 

[Clarkson46]

What year? Dynamo or Alternator? What does the extra light normally do?

 

[ronmidg]

its 1971, alternator, I think the dash light is left over from its days as a camper to show the ??????? circuits are on, as it stands I cant see it doing anything, maybe its a radio-on tell tale (if I had a radio), it comes on if insert the key and turn it the wrong way.

 

[Clarkson46]

Does the alternator have internal or external regulator? What do you mean by "turn it the wrong way", I wasn't aware that a VW ignition switch would turn the "wrong way".

 

[ronmidg]

not sure about the regulator, the alternator is buried under the engine casing, there are no odd boxes between the alternator and the battery. Just looked back and realised I forgot to say its a 1800 suitcase engine. Haynes reckons its a built in rectifier.

Insert ignition key and turn clockwise and first thing to happen is the light on the dash comes on, there is no feeling of a spring holding a detent, keep turning and the ign and oil warning lights come on, there is a detent here, keep turning and the next thing is the starter. Start the engine and let the key go back to the ign point and all the lights "go out", but shade the dash and can just see the dash light and the generator light glowing, its more obvious at night.

Insert ign key and turn anticlockwise and the dash light comes on and there feels to be a very light sprung detent.

 

[Clarkson46]

You an internal regulated alternator similar to a water cooled. The whole is contained within the alternator body. It is possible that there is an internal fault with the alternator, it would need a specialist to check it out. Unless anyone else has some better ideas.

 

[currylager]

Does the alternator charge ok even though the gen light is dimly on?. I had a 74 bay with a similar problem, this one had an alternator with an external regulator and it did as you describe for 2 years but i drove it all over the place with no problem. If it aint broke, dont fix it perhaps??. The alternator voltage sensing circuit runs through the gen light and if this bulb blows the alternator will not charge. I found this out when the dim light suddenly went out when driving and i ended up with a flat battery . In the end i used to check the gen light was dimly lit when driving to ensure the bulb hadnt blown and i knew the alternator was charging ok :lol:

 

[ronmidg]

I have no problems charging, or should say no flat battery even though bus has been infrequently used fro 18 months whilst working on the inside and the occasional short trip to stop stuff seizing up.

Understand the need for a good bulb, but hadnt seen the dim glow as a useful monitor 8)

Just a thought, both the dash light and the ign light glow in sympathy, so does that mean they are on the same circuit? what symptoms would having too low a resistance on the ign light circuit be?

 

[Araon]

Your problem indicates either a battery or alternator on its way out...

the lamp has an ignition feed when key is turned and the other leg is ground through the alternator (lamp lit), turn the key further and the engine will start up, the alternator will now put field voltage to the other leg of the lamp and when this rectified voltage equates to the ignition voltage the lamp will extinguish (thats why at times you will see it fade or flicker).

however as yours is constantly dim and brightens when further load is aplied (wipers etc), either the battery is struggling and the field side is more positive than the ignition side or vice versa, try a known good battery in its place or bench charge your battery and try again...check all the connections/batt terminals etc for corrossion and clean/replace where necessary, however as Clarkson has said it is more likely the alternator is on the way and will require a motor specialist to re work it replace the diode pack etc.., or replace with a new one....

 

[ronmidg]

have just changed the battery anyway 'cos the old one was fizzing and leaking with a bosch sealed one and cleaned up the main contacts and the glowing or otherwise has not been affected, so take it that implicates the alternator. Well its good to be forewarned, VW heritage have them for £126.

A follow on question is why, what else do I need to be looking at? Do these things wear out? or is it overheating implying something wrong with the cooling?

 

[noddy]

Was your old battery getting hot? If a battery starts to boil its usually the regulator that's gone.

Ian

 

[Araon]

Any ideas how old it is, they do wear as they get an awful lot of abuse, heavy current draw will shorten its life, have you got accessories being driven from it? leisure batteries fridges etc....corroded connectors, poor batteries and overheating will also have an effect.....