Anyways, much of the difficulty in tranferring the technique is that the original how-to used Bosch terminology which refers to a D+ connection that is tied to a diode trio as the input to the stator.

Pelican Technical Article: Alternator System Troubleshooting

Well, the Jaguar/Denso alternator does not use a diode trio. So, figuring out the equivalence is rots o' fun.

The D+ ("dynamo field") is usually tied to the charge lamp and is required for initial excitation from startup.

From reading a theory of operation walkthrough in a Toyota training manual with an almost identical regulator, in the Denso regulator diagram the two transistors to the right are involved solely in the functioning of the charge light. The transistor to the left controls the feed to the stator. The diode is not specifically explained.

 

It has to be a zener since it wouldn't conduct if it was a normal diode. Very odd, though, that it's the base of the transistor that goes into the module.
Yes the guys on the R are a darlington pair to switch the little red light.

 

Well, two things contribute to the confusion.

The diagram was copied from JTIS. It appears to be not entirely accurate. Notice how the output of one phase of the stator is drawn as connected to the output of a diode pair. Never seen that in an alternator. The rectifier diodes are also drawn as zeners, or at least something other than a plain diode. Again, not entirely sure that is accurate.

Now, I have compared the drawing to the Denso specification sheet specific to the alternator for a Jaguar X100 with a 4.0L AJ26 starting production in 1996.01 as identified on the sheet. In that diagram the "F" terminal ties to a point between the diode and transistor. It does not go to the IC. I believe that is the true case as it is the same for the Toyota tech training materials. In those materials it is explained that the base junction is forward biased by the IC to allow current flow from the rotor to ground. The drawing also replaces the upper transistor on the right side with a resistor.

In short, it's like bashing my head with the Hammer of Thor.

The topper is that the "easy access" wiring point is no longer easy as the fuse also feeds the enabling signal for the climate control, windshield autowipe and some other thing. So, it has to be done between the back of the alternator and somewhere along the firewall before the wire splice ... and all the wires are the same colour to boot.

 

There used to be 20+ specification sheets in public view on a Denso site for alternators and starters used on Jaguars. All indexed and listed on public search engines. Very detailed, right down to individual parts used, design parameters, regulator circuit schematics and output curves.

In the few days since the post above ... they have disappeared.

They didn't mind showing them to search engines, but once they realised a real person had read them, the documents disappeared.

I have one or two, but unfortunately did not archive the rest.