The 'E' Type Forum

By the way, i'm also wondering what is the purpose of the realy which is located on the LHS of the car just behind the brake bottle?

driver wrote: ↑

Fri Dec 29, 2017 3:54 pm

Hi ,Rob Gill here.
I had a similar condition on my 1971 s3,had the system checked to find it was the voltage regulator part no. C 31526 that was not working,i dont know the reason why has i am a nuts and bolts man (in other words if i cant see it i dont believe it........... like electricity).
But what i do know it started charging right away,and have had no problems since.
All the best Rob.

MarekH wrote: ↑

Sat Dec 30, 2017 10:09 am

Dear Jerome,

There is plenty of useful dignostic information about the s3 charging system on David Lacey's website. The 22RA is for the starter motor and isn't part of the alternator circuit.

The regulator itself only has a couple of transistors so is very easy to repair.

kind regards
Marek

MarekH wrote: ↑

Sat Dec 30, 2017 10:09 am

The regulator itself only has a couple of transistors so is very easy to repair.

kind regards
Marek

vee12eman wrote: ↑

Fri Jan 19, 2018 1:13 pm

Hi Jerome,

Check the earth of the regulator. Corrosion or paint can prevent the regulator from earthing and you get the symptoms you describe. The earth is just fwd of the regulator.

Otherwise the alternator may not be earthing. The original design earths through the body of the alternator and it’s mounting bolts, but some replacement alternators (like my own) have the alternator body isolated and you have to provide an earth - you need a fairly heavy cable from the earth post to the car chassis. You can earth it to the alternator body, or dismantle the alternator and remove the insulation between post and the alternator body, I did both at various times.

I wrote an article on Series 3 alternator testing for the club a while back, I can’t remember which issue it came out in, but it covered a lot of issues because I experienced several myself. I may be able to find a copy and send it to you electronically if you can’t find the issue or are not a member. I think around issue 130 or so.

Good luck,

Simon.

jagwit wrote: ↑

Wed Jan 24, 2018 7:35 am

You may also find this interesting:
Charging issues on my car

And this:
False Battery gauge readings

jagwit wrote: ↑

Thu Jan 25, 2018 1:29 pm

Jerome

The circuit to make the ignition light come on is not very complicated.
1) there must be 12V on the white wire to the ignition light (when ignition is on). This is were the current for the light comes from.
2) the Brown/Black wire from the ignition light goes via a plug and socket (does this plug and socket make good contact??) directly to the terminal on the regulator where it is co-terminated with a Brown/Red wire.
3) the Brown/Red wire goes directly to Field +;
4) Field + is just a "roll of wire" inside the Alternator - hence very little that could go wrong here.
5) the current goes through this roll of wire, and comes out at Field - and goes back to the Field - terminal on the regulator;
6) inside the regulator the the current goes through the large transistor (which should be "on") to the regulator earth.

So, lets do a few simple tests (with ignition on)
First test: Remove the terminal from the regulator that has the Brown/Black and Brown/Red wire. Ground it briefly (less than 1 second) to any chassis point that has a good electrical earth. Does the light come on during this brief grounding? This should be a most harmless test.

The outcome of this test will guide us to the next steps.

vee12eman wrote: ↑

Sat Jan 27, 2018 7:50 pm

Hi Jerome,

If the regulator was replaced and still did not fix the problem and the circuit checked out ok otherwise (have you checked that thoroughly?), then unless you were unlucky enough to get a faulty replacement regulator, then it is most likely the alternator. They are expensive but can often be easily repaired cheaply and they are not difficult to dismantle and test. I did offer earlier in the post to send an article I wrote on testing the alternator. If you pm me your email address I can send a digital copy. Otherwise see about getting the alternator tested rather than simply replacing it, just in case it’s actually ok. My comment about the alternator earth was that some versions of the alternator actually have insulated bodies, allowing them to be used in either negative or positive earth vehicles. If you don’t know how to check this then the alternator earth can appear to be fine. You have to check from the alternator earth post (which is not actually used on the Jaguar set up), to the car. Just checking the body of the alternator to the car does not actually confirm the earth if the alternator has the insulated body set up I mentioned. This was one of the many problems I encountered, along with the triple diode of the alternator failing (very simple to test, remove and replace and very cheap relative to a complete alternator).

Regards,

Simon.