1984 Hilux Charging Issues HELP

[Clubber997]

Hello all;

I recently bought a 1984 SR5 2L (3Y petrol) 4x4 Hilux, and I'm having some trouble with it. Basically if I hook the alternator up, it overcharges massively (anywhere from 18/19-22 V when idling fast when warm, around 1000-1100RPM - it'll sit at about 12/13 volts when idling cold, around 600RPM). Now the obvious thing to do is to replace the regulator - however, not only does it have a brand new regulator on there, according to the previous owner, that's the third regulator in the less than 2 years he's owned it. It's also had a new alternator fitted at some point, and a new coil (so it's obviously had these electrical issues for a while).

On top of this, the main alternator output wire has burnt through - twice (Only once for me but at least twice recently). Now my next thought was that there is a short somewhere, but aside from some crook wires near the regulator plug I could find nothing wrong with the harness anywhere. It has been suggested to me to replace the whole wiring harness, but seeing as it runs underneath both guards and behind the firewall (and includes some emissions stuff, the headlight loom, and **** knows what else within the one harness), I'm not very keen on this approach.

So. Has anyone had, or heard of anyone having, these issues or similar? Any ideas on what I should do (or if anyone has a wiring diagram or some idea what pin checks I can do, etc)? After doing some research on Google, I get the impression that I may have the wrong type of alternator (A-type circuit vs B-type circuits, or something - but this was very vague and on an American site) - does anyone know how to check this?

And finally, it has occured to me to upgrade to a Bosch internally regulated alternator with a bit more grunt - maybe 80 or 90 amp (for down the track). Does anyone have a rough idea how much is involved in this, and if there are any drawbacks (are the later model bosch alternators less water resistant or something, etc?).

Sorry for the long post, and thanks in advance!!

[trentmeyer23]

If the sense wire is corroded/damaged overcharging can occur.

[Clubber997]

Would this cause regulators to bust themselves though? And the thing is, the charging system was working (mostly) fine until a couple of days ago.... And I don't think this would cause the alternator output wire to burn out?

[trentmeyer23]

If the sense wire has a high resistance, the regulator will think that battery is constantly under charged.

A dodgy battery can kill regulators as well.

Loose connections, high levels of resistance and corrosion can all cause issues.

[Clubber997]

Hmmm... I know the battery is pretty old, and I know the terminals/some of the cables are pretty dodgy. Oh well, I guess getting the alternator tested/new reg/new reg plug and wires/new battery terminals and main/earth leads, and a thorough inspection and replace anything else found to be dodgy along the way... Thanks heaps Trent, and if anyone else has any other ideas/input hit me up!

[Clubber997]

Just another question, there are 6 wires going to the regulator - does anyone happen to know what they all do, and which ones are which?