Thread: Alternator problem

I conected one wrong and it did funny stuff. Mine has an external regulator. My friends new altornator was wired wrong in the plug. If it an internal reg there is usually a bolt that has a live feed to the and the plug has a warning light and maybe an rpm or battery sense.
If its external the plug would have several more Not sure where they go now. I think one goes to the feild and one to the armiture. Had to change the the way the plug was wired on my mates car to make it work right. So just because the plug fits it does not mean its correct. Its not like a shirt. The new altornator to regplug was hooked up wrong even though it just pushed in.
Did the prob start all by itself originally or was somthing changed?

Originally Posted by rar110

Not yet, still unplugging the alternator each time I stop.

Tonight I discovered the two alternators have a slightly different pin setup

One is like this:

_ _
I I

The other is missing the 1st vertical pin, and so has only three pins.


Can anyone tell me where each of the 3 pins in the 2nd type go. The colour coding on the wires isn't correct at the plug end. I've got a wiring diagram which I don't understand.

I have four wires on my plug and so am trying to work out what the 4th goes to

Is it all good now?
What was the fix in the end?

I fitted a new alternator on the weekend. Its charging nicely, and this morning started quickly. Tonight, off the train and into the 110, battery flat 11.4 volts. What the hey. By the time I got home the battery was up to 12.4 volts. A bit over an hour later its down to 11.5 volts. The same as when I fitted the other replacement alternator.

A quick recap, previously the battery stayed charged if I unplugged the alternator. That has been my routine every time I stop for a while. Pop the bonnet and unplug the alternator. So its not the battery.


This has been a problem since April and have fitted two replacement alternators without success. The joke's wearing a bit thin. Any thoughts?

Originally Posted by rar110

I fitted a new alternator on the weekend. Its charging nicely, and this morning started quickly. Tonight, off the train and into the 110, battery flat 11.4 volts. What the hey. By the time I got home the battery was up to 12.4 volts. A bit over an hour later its down to 11.5 volts. The same as when I fitted the other replacement alternator.

A quick recap, previously the battery stayed charged if I unplugged the alternator. That has been my routine every time I stop for a while. Pop the bonnet and unplug the alternator. So its not the battery.


This has been a problem since April and have fitted two replacement alternators without success. The joke's wearing a bit thin. Any thoughts?

Do you use a multi meter to do your testing or is there a volt meter fitted?
What brand of alternator are you using? There were two types used as far as I know. Mine is Hitachi I have repaired it several times with no real issues just bearings and brushes.

Original was hitachi, so was replacement, last was onehunglow eBay special.

You sure its not an external regulator?

Bloody hell Pete, have you run over a Chinaman or something???
Sounds like it may not be the alternator itself but a current drain or short somewhere.

Pm me