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Alternator Wiring


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Having got the engine back from the rebuilders I am in the process of putting her back in.

I took photographs of the wiring connections but I'm b***ered if I can find them.

Can anyone post a picture of the connections to the Alternator with the colour coding clear?

It's a Three pin alternator from a 69 TR6..

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I don't think a '69 TR6 originally had a three connection alternator Pete - that type didn't appear until later so this may be a substitution, in which case the loom might have been modified to suit.   The following assumes this is a Lucas ACR type. (if it doesn't look right, can you post a picture of the rear of your alternator?  

I guess you don't have a three-way plug as that would be obvious, but are using separate connections.    The brown/yellow wire has a small spade connector and goes to the matching small terminal on the alternator.    The two large spade connectors on the alternator are both +v output and either or both can be used.  Some cars may have two slightly thinner wires instead of one thick one -  either brown or brown/white.  In any case the large spade connector(s) would be unmistakeable.  

acr.jpg.2a37d56ace505017ce00650d9f46f7c7.jpg

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No it really doesn't matter Pete. The two big terminals are connected together inside the alternator. 

I'm not sure whether this is a typo in your reply: ".......the thick brown/white or White connect to? ...."  Should that have been 'brown' ?   Plain white wires should be reserved for things switched by the ignition switch and it would be unusual for that to be used for the alternator connection.  

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These are the wires that connect to the alternator.

The two on the left have a large spade terminal and are (from left) White and Brown/white.

The two on the right are (from left) brown/white and brown/yellow, I am not sure if the brown/white wire was knocked off when disconnecting?

AlternatorWiring.jpg

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Oh dear.  Sorry Pete but this is getting complicated as it looks as though that fat plain white wire is some sort of modification - it doesn't fit with any published information I have.  Neither does the thin brown/white wire as there shouldn't be one in that position. 

The stub of wire showing on the small connector is probably the remains of the link-wire which was cut off when the change was made from a 5 connector alternator to a 3 connector one.  If so it would have been brown/yellow.  No other wire connects there. 

Before conversion it would have looked like this:

bfr.jpg.804ea5d8f68734e2dc63ca3979f22456.jpg

 

 

That thick white wire might be the feed to the ignition switch (which is shown as a brown/white wire in the diagram, running from the ammeter, but connecting to the alternator instead would be OK)  and the thinner brown/white might possibly be a feed for the lighting switch though it looks a bit thin for that.  

 Neither the earth nor the brown/red wire in the diagram are needed for an ACR alternator and should have been removed.  

If you have the means, I suggest it would be safest to trace out the wiring with an ohmmeter before connecting anything. I don't think you could rely on photos of other cars since their modification might have been done differently. 

 

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I suspect the white has been a substitute for the feed to the ignition light as theyve obviously done away with the separate regulator box that was fitted to early cars and was fed from one of the brown and yellows originally

Stuart.

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I’m always a bit wary about saying anything about electrics when Rob is involved in the conversation, as he knows a lot more about such stuff than I do, but logically speaking….

You have two wires with large connectors on the end.
You have one wire with a small connector on the end.

The alternator has two large spades, and one small spade.

It is known that the two large spades are connected together inside the alternator, so there  is really only one way to put it all back together. (Seeing as it does not matter which large connector goes to which large spade.)

The other wires?
Nowhere for them to go.

Looks like a bit of a bodge when it was converted from a 5 wire to a 3 wire system. Whoever did it probably never bothered to tape up the loose ends.

(I will still bow down to Robs greater knowledge though, if he thinks I’m talking bow-legs.)

Charlie.

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21 minutes ago, Charlie D said:

if he thinks I’m talking bow-legs

No you are probably right Charlie - if Pete definitely knows that all the wires were connected to that alternator once, it obviously does go back that way.  (but where did that unconnected wire go?  Probably to the big brown/white?  Certainly not to the small tag)

The problem is that memory can play tricks .  If he is not sure but connects it all anyway, it could cost an alternator, a wiring loom or worst case a whole car.  A few simple checks can prevent that. 

 

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10 hours ago, BlueTR3A-5EKT said:

Have you connected the temperature sender wire?  

Thats a green/blue so should be obvious.

Stuart.

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