With the connectors at both ends already determined the only open question was the length. I’ve pretty much decided to mount the voltmeter under the dash shelf so, armed with a ball of twine, I went out and worked out a routing. So the answer to: “How long should the fly lead be?” is: “As long as a piece of string.”
Making up the fly lead was the same as making up the voltmeter connector but with the gender of the connectors inverted. A wrap of the wires with black insulting tape to keep things tidy and it was finished.
The final QA check was to mate the voltmeter connector and the fly lead and, using a multimeter, check the wiring end-to-end.
In order to connect a wiring loom extension to feed the voltmeter it will need piggyback connectors for earth and dial illumination. Whilst it would be possible to use some off-the-shelf piggyback connectors they’re not the easiest to fit in the confined space behind the dashboard.
With a few lengths of wire and some connectors it didn’t take long to make up a pair of leads suitable for the job.
The male spade connectors will fit into the wiring loom and one of the female connectors will go to the speedo which will maintain the original circuit. The second female connector will then be available for the wiring loom extension for the voltmeter.
The connectors on the wiring loom are as follows:
Speedo earth: brown
Speedo illumination: white
Voltmeter live: purple
Using green and black does vary from the connectors used behind the dash but keeps consistent with my colour scheme for the voltmeter. My piggyback to wiring loom connections will be as follows:
black -> brown
green -> white
With the piggyback connectors in place there is a bit of room for manoeuvre but the wiring loom extension will benefit from having several centimetres of free wire for each connector to reduce strain.
Auto electrics aren’t exactly a paragon of reliability so couple that with a classic car and anything to help out is useful. Of particular use is a voltmeter as this will often give an early indication that something is amiss.
Whilst the Club speedo came with a “battery condition meter” the Spécial’s dashboard was more minimalist. Fortunately – as with the dashboard indicator lights – Citroën used the same wiring loom for both models so the live connector for a voltmeter is already there. However, one live connector isn’t enough for an after market voltmeter, it also needs an earth and a live for illumination. As the voltmeter on the Club was part of the speedo that already had earth and illumination no additional connectors were provided so an extension to the wiring loom will be needed.
As I’ve not decided how and where to mount the voltmeter I want to make the job of connecting it to the wiring loom easier so I went for a short set of leads from the dial terminals to a connector block. This means the hard to reach connections to the dial and the wiring loom can stay attached and the connector can be in a more accessible place.
With the connector made up it fits onto the terminals of the voltmeter and the connection block can be presented in a more accessible location giving more scope for finding a practical mounting point in the car.