Problems with my alternator charge system!

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VISONTE
Posts: 1
Joined: Wed Oct 14, 2020 11:41 am
Car(s): 1981 FORD CAPRI 2.0S

Problems with my alternator charge system!

Post by VISONTE » Thu Oct 15, 2020 10:29 am

Hello from Spain everybody! I have electrical problems on my 1981 2.0S , There is something wrong on the charge system of the battery and alternator, the light of alternator in the console is always on, this is a new alternator, i bought other one thinking it doesn't works but the problem is not on the alternator , the problem is that the alternator doesn't receive the 12v voltage from the excitation wire,with the contact on i get 2.75v from the blue wire ( the alternator excitation ) , and doesnt start to work, if i put a direct wire from the battery + connection , it gets excited and in this momment if starts to work and charge the battery ) the light of the console turns off in this moment ) but the belt of the alternator starts making a big friction noise, it seems that any magnetic force inside the alternator try to stop it! and makes lot of noise! idea of how i can fix it? Anybody has the electrical wiring diagram from the 2.0S ? thanks a lot!!
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stevemarl
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Re: Problems with my alternator charge system!

Post by stevemarl » Thu Oct 15, 2020 5:21 pm

VISONTE wrote:
Thu Oct 15, 2020 10:29 am
) but the belt of the alternator starts making a big friction noise, it seems that any magnetic force inside the alternator try to stop it! and makes lot of noise! idea of how i can fix it? Anybody has the electrical wiring diagram from the 2.0S ? thanks a lot!!
Hola!
The belt noise sounds normal, as the alternator is suddenly putting a lot of charge back into the battery (after it`s used hundreds of amps to start the engine) the electrical energy it`s putting back into the battery will result in the altrernator itself demanding more mechanical energy (ie requiring more `work` to turn it) thus becoming harder to turn so the belt squeals. This sounds normal.
Most alternators WILL self-excite anyway once they reach a certain speed, 2k or so, as the residual magnetism will induce sufficient current in the field coils. I mistakenly put an LED in my Ignition lamp, so there`s not enough current to excite the Alternator, but as soon as it reaches 2k it switches and stays on as normal, (incl tickover) so I`ve just left it. Will yours not self-excite if you actually run it?
I can only assume there must be some kind of fault between the Ign lamp and the wire into the alternator, as the lamp is lighting: With a digital meter (10Mohm/V) you should get full 12v on the earthy side of the bulb, 2.75v is odd. Normall it simply earths through the alternator coils, hence it`s extinguished when they go positive.
edit: any idea why the 2 thick leads from the plug have been chopped &b soldered onto a single lead: where has the other thick red lead gone to? It`s always a problem when people have been chopping up the original loom, (a previous owner obviously - not pointing the finger :D )

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