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MG MGB Technical - alternator

hello i have a very dim alternator light on all the time ,yet it was replaced last year any one got any ideas
daz

Might be a bad diode pack in the alternator.


Derek Nicholson

Could be an earth leak. I had a similiar problem at one time. When I was doing Right Hand turns at night the alternator light would also flash dimly. It turned out that my RHS indicator was not earthed properly. The bullet plug near the RH horn had come unplugged. At some stage some one had "fixed" the problem by earthing onto a convenient nearby screw.
Your best approach might be to dissconnect the battery and do an ammeter/multimeter check between ground and various parts of the loom. If you get anything less than infinite resistance you know you're on to something.
Peter

If the glow gets brighter with increasing load then as well as a faulty diode (infant mortality is all too common these days) bad connections between the alternator and the solenoid or the solenoid and the ignition switch can be to blame. With the headlights on and the engine running at a fats idleMeasure the voltages on the brown and brown/yellow at the alt, the battery cable at the solenoid, and the brown and white at the ignition switch. In a perfect world they would all be the same but there are bound to be some differences, but they shouldn't be more than 0.25v. If the alternator brown and brown/yellow are both the same and the other points are lower then there is a bad conenction between the alternator and the solenoid. If the alternator and solenoid readings are the same but the brown and white at the ignition switch are lower then there is a bad connection between the solenoid and ignition switch. If the ignition switch white is lower than all the others then the ignition switch is high-resistance, check the steering column multi-way connectors as well if you have them. If the brown/yellow is much different from the brown at the alternator then it looks like an alternator problem.
Paul Hunt 2

thanks for that ,its a lot to take in but i will go through it slowly thanks
daz

This thread was discussed between 03/04/2006 and 04/04/2006

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