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hello, just fitted a new brand alternator not a recon and the battery light is still on, the battery its self is fine, what else could it be? thanks
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Is the alternator charging, do you have 14+ volts across the battery with the engine running?
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hello peter, the alternator is deffo not charging, cant give you anymore info apart from the single wire to the alt. was a pig to remove and resulted in the plastic retainer got broke and the push on is at the alt. without it,also the heater blower is now not working john
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I would guess that the thin single wire is earthed instead of being connected to the alternator. If the lead was in the right place the light being on would indicate that the alternator was being energised, the only other way the light would come on is if it was connected to earth or the alternator was duff or not turning. Check your connections again.
Peter
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hello peter, since reading your reply i have done a little research with google and now understand a little more about how the alternator has to be energised. your suggestion of the energiser wire not on the alternator properly and earthing seems spot on, could you tell me if i will have blown a fuse by doing this or is it just a matter of connecting it properly? thanks john
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Hi John
No it will not have blown a fuse, as you have probably observed from your research the alternator is energised via the charge lamp, so if you short the connection to earth all it does it put the lamp on. What should happen is once the alternator starts charging the voltage on the enegeriser terminal goes up to 12 volts, as the other end of the lamp is connected effectivly to the battery, you have 12 v on both ends, hence no current flows and the lamp goes out. Simple but effective system. A similar arrangerment has been used since cars first had electrics.
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thanks so much peter,would it be possible to connect a multimeter to this wire, and what voltage should it read?
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Just to add to PNs excellent info,I would suggest check the large output lead from the alternator to ensure there is a good solid voltage .Use a test light with a bulb(rather than led type).Also with ignition on and thin wire disconnected,the charge light should be off.If it is on ,then the wire is earthing at some point.hth
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hello, i have test the main wire and got 12.5 volts, then tested the single wire with ignition on and no volts, plus the red light is still on with wire disconected, please help
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Well, that indicates that there is a short to earth on the thin single wire which is why your alternator is not charging. You will have to follow the wire back to the loom and cut the loom sleeve if necessary to find out what has happened to it, unless you have had the instrument panel out in which case there could be a fault that end. If you connect your meter between the lead and earth on the ohms range, it will probably read no resistance at all, just the same as if you connect the meter leads together.
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thanks again peter,where does the other end of this wire connect too? it may be easier to put a new wire from the alternator to where ever thanks again peter
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I have this this fault once before on a diesel and found that the warning light wire was trapped/shorted near the nearside suspension strut where tthe main injection harness multi connector is located.Remove the air cleaner box for better access and give the wiring loom a close inspection.If you undo the connector (1 10mm bolt)and recheck the system with ign on,if the light does not illuminate then the fault is somewhere between this connector and the alternator.hth
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thanks doc, will have a look john
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hello doc, and peter N, and anyone else, still no go with the alternator, the warning light is still lit and showing no charge at the battery. could you tell me if it is possible to check the voltage at the alternator rather than at the battery to see if the alternator is charging but not getting to the battery? thanks
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If the light is on it wont be charging, if you want to check it out, connect a wire from the battery+ to the small terminal on the alternator but disconnect the existing one first. I think you will find its now charging. If you are feeling brave you could touch the 12v lead onto the terminal with the other lead still connected and look for the smoke, that will tell you where the short is.
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thanks again peter ps watch this space john
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