I have a project 1965 Mark 2 that has an XJ6 series 3 engine and Borg Warner auto gearbox grafted on by a previous owner. Wiring was not completed and I am left with a problem. Speedo is removed and the ignition warning light is unconnected. Shown in the photo is a green wire live from the battery through the ignition switch to the centre bulb terminal. The casing is connected to 2 white wires with green stripes. One can be seen clearly in the photo and the end terminates in a flag terminal under the insulating tape. The other white with green stripe wire dissapears into the loom along with the green live wire.
My question is where should the loose white/green wire go? Further confusion is that I presume the white/green wire that cannot be seen in the pic except where it tees with the unconnected wire just before the bulb holder, would have run back to D terminal on the voltage control unit. But the dynamo has been replaced by a Lucas alternator, eliminating to VC unit. This alternator has 2 large spade connectors and a smaller black one. The two large spade connectors were not plugged into the alternator, but just sitting near the terminals.
The wiring colors do not correspond to the several wiring diagrams I have from Jaguar and a couple of service manuals. They all show the power wire to the warning light connected also to the low brake fluid warning light and also to the fuel pump. The wire from terminal D should be brown and yellow and the power wire from the fuse block should be white.
Lastly the two white/green wires connected to the bulb casing will be earthed to the speedo when the bulb holder is plugged into it. I cannot follow this at all since Termial D would be applying opposing voltage from the dynamo to extinguish the warning light when charging the battery. Answering my own query, a probe with a continuity meter shows the outer clip ring is not in electrical contact with the shank the wires are joined too. The shank and wires contact the bulb holder, which answers that part of my question. But where is the other loose green and white wire with flag terminal meant to go?
Can anyone help with some explanations please.
I do not wish to bring in an auto electrician, since the whole spirit of my old car hobby is to learn and do things myself.
One final point is that years ago a sparkie was asked to add more fuses and circuits. There is a 6-fuse aftermarket box where the old VCU was fitted and a relay that I have not plotted out yet. This sparkie did not complete his work before emigrating, which is why there are so many loose wires in the instrument panel.
Lastly the engine has not run since 1987 so I cannot test alternator output in the car until I get to this and make sure everything is still free and valves will not be bent.
SAJ in NZ
The Ignition warning light has indeed one green wire, that has +12V when ignition is on.
The other wire should go to the alternator ( the small black terminal ), I presume this alternator has a build in regulator. You should also connect the 2 wires from the AMP meter together. The current from a alternator is to high for the amp meter, I replaced the AMP meter for a Volt meter.
Thanks RuschP. The ammeter is live both sides but not registering . Maybe burnt out by the alternator if and when the car was ever test run with the 4.2 XJ6 engine, or just corroded internally like my wife’s Mark 2 ammeter was?
But where does the other loose white/green wire connected to the same wire that runs back to the alternator go? It has a flag-shaped ring terminal and this wire is not shown in either mark 2 or XJ6 wiring diagrams. In the photo it looks like only one white/green wire but there are 2, both joined to the bulb casing. The one you can see is the loose wire. The one that should run back to the alternator cannot be seen. I will check its continuity from both ends tomorrow, since the bulb does not light at present, though the bulb itself tests out ok.
The alternator does have an internal regulator.
SAJ in NZ
There should only be one wire from the alternator to the ignition light.
I would remove the other wire.
If you know how to solder they are not difficult to repair. There is a simple copper wire loop. I replaced mine with a piece of 14 gauge.