does anyone have any ideas what could be causing my battery light to flicker (at low revs) and glow bright at high revs.
i have tested the alternator (13.5-14.6v) and the battery loaded and unloaded, neither reading below 13v.
the voltage regulator in the alternator is fine too as it is giving out a nice even charge (no surges)
the only key events that could possibly of contributed are ,
1. the battery in the remote keyfob became flat causing the imobilisor diode to flash constantly when engine runs
2.the battery on the car was totally flat one morning, but charged fine and hasnt run down again
i am totally confused as i have tried all the sensible diagnostics and still am non the wiser , the beers are on me if someone has a good solution!!
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please someone help!!!!!!
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Loose wire from the alternator to the light, or possibly intermittantly shorting to the live wire at the alternator?
The 240 is prone to this, because of the tight wiring down by the alternator, and accumulated road muck, causing the wires to corrode together.
I don't know whether this could happen on yours.
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yeah, thanks, i have checked the wires on the alternator and the feed to the warning lamp had a perished cable, i replaced it with a new one two days ago, the fault remains!! thanks for the reply though.
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How many times 100,000 could be the brushes, change a few regulators due to worn brushes at 100 to 120k I assume the engine earth strap is AOK. Regards Peter
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cheers, yeah the engine earth is good, and surley if the bushes and or regulator are tired the output would show this?
its a very odd problem, thanks for your reply though pete
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No your voltages say it's Ok but if you look with a scope you will see the brush noise during heavy load. The brushes only handle the current for the feild coils, thats the rotating armature of the alternator and the stationary coils are rectified and output as DC into the huge capacitor call a battery thats smooths it all out so very difficult to see. If you can remove the regulator without too much difficulty then that will be the only other way wat to tell. How many miles has the car done. ?? Regards Peter
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Ooops typo's as well. Peter
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Just change the alternator and stop pink fluffy dice about
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Change the alternator???,there is in the rear of the alternator a variable diode for the ignition light this breaks down and and allows the light to come on .The options are 1.live with it,2.remove the alternator use a multimeter to find the faulty diode (diode kits can be purchase)or 3.spend a fortune on a new alternator.
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4. get a secondhand alternator from a scrapyard and try it.
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Thankyou Cliff
Welcome to the world of "I'm skint and I need this car working now!"
Measuring traces on scopes is admirable but it takes too long if you ask me. The flickering tells you exactly what is happening. In real life you would probably spend more time and money on probing the alternator's output, buying a new diode pack and fitting it than actually getting an alternator from a scrappy. You would then have a spare to fit a new diode pack at your leisure for emergencies or to sell on. If you're that keen on electronics, you could solder up a nice new set of diodes from Maplins for next to nothing.
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ok, i am skint and trying to avoid any expense, how long will a faulty diode take to destroy somthing bigger? thanks for all posts(almost,u know who you are!!)
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I am pretty sure you mean me. I apologise for any offence, none was meant. I was brought up with bangers that my dad needed for work. They just had to be fixed, quickly. I work in the electronics industry and fix rf circuit boards for a living. It is actually very difficult to diagnose 100% exactly why electronics go wrong sometimes and taking the old diode pack off, buying a new diode pack and then fitting it for instance only to find that you had wasted money and time is not my idea of a good day out. I prefer the - get an alternator cheap (scrappy) from hopefully a newer model crashed car and fit it to get you back on the road. You can always take these back if they don't work and swap them. Try that with a shiny diode pack! Then you have your original alternator to change the diode pack or regulator at your discretion (when you get some dosh). You can then keep it for a spare or flog it.
Good luck anyway.
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Not actualy correct,if you have worn/stuck brushes.one is liable to short rather than contact the commutator.it can occur that the brush shorting out destroys the copper-leading to out of round commutator,common problem back in the seventies/early eighties
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Steve
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