JowettTalk

i've just bought a wiring harness from autosparks. it is due to arrive in
Australia shortly. do you have any hints and tips on fitting a new harness
to my 1950 Jowett. Any advice you could give me would be greatly
appreciated.

regards

Phil squire

Previously I bought a wiring loom via the club for the SC Jup and had to make a few mods. Jack also bought one from the club for his Bradford.

First thing to do is to get a correct wiring diagram and blow that up as big as you can. See Gallery for most of the diagrams. Using a computer with a zoom facility is good for failing eyes! Identify all the different cable colours. Worth checking against the diagram as you take the old loom out and marking each wire on the new cable with a label or numbered rings.

The main problem area will be the dash panel and it depends if you have all the instruments out and refurbished or if they are all in situ and connected. Most cars will have some wiring mods that need accommodating.

Clearly understand where all the cable runs are, and check the lengths of the new cables against the old. Make sure all the rubber grommets are in good condition and where P clips are fitted.

You will also see by searching for 'wiring' on jowett.org (type this into Google search wiring site:jowett.org) that I drew a logical wiring diagram showing how current flows from the battery to all the components. As you fit each component you can check continuity or even operation with battery connected. This will greatly aid fault reduction and finding.

Make sure all crimps are good and there are no overcut wires which are thin. Make sure all fitments match the appliance they are going to.

There is a movement over here of fitting LED bulbs EVERYWHERE. Halogen bulbs were much more reliable than the older filament and the LED may be even better. One thing is certain is the dynamo will have less to do. I do have concern with LED's ability to withstand high temperatures and spiky voltages but worth considering if you are going this far at renewal. The high temperature may be of concern in Aus, I have had experience of electronic components being fried in strong sunlight. (This might occur where the sunlight is focused by the headlight reflector onto the LED assembly.)

Thanks Keith I'll let you know how I get on

Best advice I can give you is that the voltage regulator box might not be laid out as it appears in the wiring diagram. The front of the box shows which terminal is which, and this is something which is worth taking off and testing/checking before you attach the dozen wires to it.

Agree on the size of the diagram - if you can get one and blow it up to at least A3 size, trying to read the tiny text when it is so easy to get blue/white mixed up with white/blue and particularly the dashboard end of the loom can get a bit complicated.

Also if you can lay everything out and work out what connectors are required, soldering on bullet connectors or stripping wires is much easier to do on the bench before you fit the loom, trying to solder under the dashboard above where you are lying is a great way to get solder on your head.

Finally the loom I got from JCS had some wires which were similar but different colours where plastic had been used instead of the old braided cover - the thinnest wires for some things were purple/white, presumably because white/purple wasn't available etc. So double check before assuming the diagram or car is wrong.

Jack.

Lucas was fairly fixed in color of wiring over the years.

One color wires are feed wires (ignition,lights and such)
Two color wires are switched. Main color is for the circuit group and the second for individual circuit.

Typical uses until the '70's:

Black: ground
Brown: Main battery to regulator and feed to items powered directly from battery
White: Ign and all non-fused that are hot when ign switch is on
Green: All fused accessories controlled by ign switch
Blue: Headlamp circuit
Purple: All fused items not controlled by ign switch
Red: Parking and tail lamp

Does anyone have a copy of a wiring diagram fora 1950 jowett javelin deluxe. I can't find one on the website

I have a copy of a wiring diagram for a 1950 Javelin. If you can contact me via my E mail address, which can be found on the back page of the 2014 Membership list, I could send you a scan.

Robin please put in the Gallery if it is not already there. But I think this is the one. https://jowettnet/forum/download/file.p ... &mode=view

Whilst access to the engine bay / lights / bulkhead & dashboard are all straight forward - the run of the loom from the front to the rear of the car is not - it travels up the drivers side A post / windscreen pillar - along the right hand roof rail and down the D post into the boot area - this is on Right Hand drive cars and could possibly be handed to the left on left hand drive cars - this will require at the very least localised removal (if not complete removal) of the headlining to gain access to the harness - from experience I would advise pulling the old harness through from the front - but at the same time attaching a pull cord to assist in drawing the new harness through to the back. Dependant upon the condition / age of the headlining it may be wise to fit a new one at the same time / once you have the new harness in place and tested. There will be images of the removal under the thread of 'Early Javelin Restoration' - within the Javelin section of Jowett Talk - although I am unsure to what page.

Chris

The headlining strip down starts here
With the cable down the A post here.
The relevant post is here.

The wiring diagram on Jowett Gallery looks like a 1950 version by the headlamps. But, it is for a Standard model, not a De Lux. Some else has my collection of Javelin papers, so I have to go and find it.

Thank you I really appreciate everyone's help

The Javelin PB Wiring Diagram is here kindly provided by Andrew Henshall.
He unfortunately scanned it as a pdf document which was upside down, so I had to use Adobe Professional to turn it the correct way up.
A single page is usually better to scan as a jpg or png image which can then be rotated by JowettGallery tools if you inadvertently upload it upside down.

Here is the pdf transformed to a png file for display here. Note a higher resolution version is available in the JowettGallery here. I took the opportunity to use Photoshop to crop the image, but most photo editing software can do this.

Robin Fairservice provided a scan of 1950 Javelin on which I used Adobe Photoshop to crop, rotate, adjust contrast and brightness and then I removed colour information to make it 'grayscale'.

As I said elswhere some scanning software can remove background smudges to get a better image.
Anyhow here it is in the JowettGallery.