I last used the car a week ago, just t get it out of the garage so the central heating oil could be delivered.Tomorrow is Madame's birthday, so i went to buy the ingredients for her favourite dinner.
Turned the key, engine spun over, NO START HORROR OF HORRORS.

• Checked for 12v at coil, OK
• Fuel smell, so assumed fuel ok, pump running audibly etc.
• Checked for spark from the coil lead: NO SPARK - so maybe the amp has given up?
• Swapped in my spare amplifier (Lucas car) very quick to do
• Tried starter, NO START.

So it has to be something in the dizzy. Rang Grant on the Franco/Oz hotline: what to do next?
Grant said:

• Cannot be the dizzy cap or rotor as no spark from the coil lead - good point that had not occurred to me
• Next he said: "have you ohm'd the pickup?" I knew what the pickup was and did, and indeed had fitted a new one a few months ago; but I had no idea what to ohm or what the values should be. Herewith the tale:

On the the Lucas car the dizzy works as follows. The amplifier needs a signal to tell it when to fire the coil. In the dizzy there is a star wheel with 12 points on it, as each point passes a magnet (the pickup), a slight change in voltage is caused (called the Hall effect) and this provides a signal to the amplifier to tell it to fire the coil.
The pickup unit is bolted to the dizzy chassis and it has two wires coming from it, exiting the bottom of the dizzy, and going into a rubber plug. The lead the other side of this plug has a similar rubber connector and that goes to the amplifier. Grant told me to disconnect this plug and test it for the correct ohms in the pickup, which should be 3.1 ohms. pic of a pickup:
https://www.welshent.com/Jaguar-Igni...89-P25474.aspx

Correct ohms for the Lucas HE pickup:

Lucas ignition HE V12 distributor pickup correct ohms

This I did, ZERO ohms. So I tested my spare pickup - the one I had renewed a few months ago: 3.1 ohms! So something up with the new pickup, zero ohms = no circuit = no signal to the amplifier = no signal to the coil = no spark = no start.
Then although not easy, i had a good look at the plug coming out of the dizzy (one male one female part) to make sure my meter was making good contact. And I found that the female hole had no metal sleeve in it, then I saw this

The female plug sleeve has detached and come out on the male plug pole.

So the NEW pickup's rubber plug was defective, as the female copper sleeve was not properly connected to the pickup wire. Mercifully, the car, most graciously, had decided to give up the ghost in my garage, rather than in the rain on a winter's night far from home! I emphasise, nothing caused this, the car turned off normally a week ago and today it would not start. That plug must have been working since new by a miracle!
I therefore cut off the plug and with great difficulty as there is only about 2 or 3 inches of wire exiting the dizzy base, put in two permanent straight connectors joining the pickup wires to about 8 inches of silicone wire. pic here:

Straight crimp connectors and extended loom
Then I wrapped the connectors in self amalgamating tape to strengthen and protect them:


I then cut off a spare rubber plug to join to my extended leads. I ohm'd the leads from the connectors and all good. Then I used those solder-joiners in tubes that you heat to make a connection from my extended leads to my repurposed spare rubber plug:

Then i plugged it into the amp and tried the starter: NOTHING
So I then ohm'd the joined-on rubber plug: ohms all over the place! So the repurposed plug, and/or my soldered joins were rubbish. Remember I knew the new leads ohm'd OK. So I cut off the plug and fitted Anderson Powerpole connectors - which are the bees knees - to the leads, and bravely cut off the OEM plug on the amp lead and replaced that with Powerpoles, and plugged them together:

VROOOOM! she started straight up. Here is the finished job, Powerpoles nicely fixed to the fuel rail, spare amp also converted to Powerpoles.

I take from this the following:

• my new pickup had a faulty plug and I was very lucky not to be stranded
• new parts are no longer the same quality or reliability as genuine "of the era parts" were
• the OEM rubber plugs, now in my case 37 years old, are VERY likely to fail if pulled apart, if you have to, replace them after you have had to separate them.

 

Good point about the rubber plugs. I had one terminal fail of three in the cruise control actuator harness. It was a bear to track down as mine had failed inside the molded rubber. I finally started testing continuity while carefully moving wires and connections and found it.
Jaguar/Ford made a big deal out of getting rid of that style of connector in the 1994 model year update. They had started changing over to multilock and econoseal connectors in earlier years, and finally changed over completely in 1994. Good riddance.