F7P Alternator Q

[T.J.]

This ones bugging the hell out of me, I just need to find a straight answer.

How many connections should there be on the alternator? I have:

the big red charge wire (obviously)
A plug with 2 spade connectors - presume these are the regulator in/out?
a brown wire that I can't seem to attach anywhere

So, It's all a bit of a muddle and must be the root of my charging woes. I was sure the brown wire I have floating around the inner wing was an alternator earth, but can't find anywhere it's supposed to attach. I consulted the manuals for both volvo and renault and still no clear answer. Really need to hear from someone that has it all hooked up already

[Chris_C]

Brown wire should have an orange wire tied to it, or on a separate ring but loomed together.

Orange is earth for the Renix (as was... should now be from your Renix replacement coil) Brown is one of the earth attachment points for the main loom (I've stripped a loom recently...) That brown earth works like a ring main in your house electrics and should be connected onto the alternator M4 stud which is at the 2 o'clock if the main +ve wire is at 10 and the regulater plug which you've got right is at 12 (also, different alternators have different numbers of connectors in this plug, either just 1 or both. I have had both on Fake, both work and charge correctly, and the charge light on the dash functions correctly with both)

Something I've seen on my car and others is the alternator earthing through this earth stud into the loom to return to the battery, this is wrong and means that the main earth strap on the block is corroded. It also means the starter is earthing through the alternator. At full charge rate the alternator can melt the M4 stud (again, don't ask why I know) and then when you put a new one in earths through the stud as you havn't fixed the correct problem and earths on the passenger headlamp, melting the loom (which isn't at all why I had to strip the loom recently either )

[jon-ovlov]

What Chris said. I'm at the car today just tweaking, so I'll get a pic and post it up. I ended up adapting my old 1.4 alternator to fit, as the one that came with my engine didn't work, but on inspection, both the renault and 1.4 volvo alternator had the same connections. as well as being similar in size and other dimensions.

Btw Chris, your laser pointer turned up today. I'll do that today and get it back to you tomorrow

[T.J.]

Thanks guys.. kinda confirmed what I'd thought.

I went out and hacked at my alternator. The ground stud had a plastic casing round it for some reason, so i cut a slot to allow the crimp to sit in there.
All attached, and still no charge. To be honest I think running it without the ground connected has probably killed the alternator.

[Chris_C]

The alternator earths through the block, not the other way round. Is the earth strap good?

Jon, nice one bud, thanks!

[jon-ovlov]

Here's a pic of the rear of my alternator. It should look summat like this.

[T.J.]

Hmm, mine doesn't really look like that. I don't have the earth bolt. Instead mine are covered in plastic like the 2 at the bottom of yours. Thats the bit i hacked off to attach them.
Is that a volvo alternator or a renault one?

Chris.. Was just thinking if the regulator wasn't grounded properly it misght not be functioning. Maybe running the alternator at full power all the time has burned it out. I dunno just ideas.
Anyway, i should be able to check the earthing by putting a dvm between the + terminal and the casing with the engine running

[Chris_C]

The earthing isn't quite that simple, as impedance changes relative to the current flowing across a dodgy joint. Hence it looks ok to a meter, but to the alternator (or the starter) it is basically open circuit (ok, thats epically simplified, but makes the point)

Both the Volvo and the Renault alternators should have the earth stud, though might vary per model. FWIW, has the earth and the +ve round the other way though (which is now worrying me... thats the way they have always been but are they right :s )