About to rewire my Mk2 RHD with all new looms. ? any tips or words of advice

Hi all, I am now at the stage I want to make a start on rewiring My RHD 1964 Mk2 3.4 with manual g/box following a bare shell respray.
I will appreciate any tips on the best approach from someone who has ‘been there and done it’. I am keeping the car factory standard including positive earth.
Thanks in advance.

I’m in about the same stage now, so would like to ask about Your reasons for replacing the wiring - what were the symptoms of deterioration ? I assume that if You’re adhering to factory standard You’ve been considering keeping the old one ?

My thoughts in the subject are: “wouldn’t it be wise to get rid of all hidden interconnections in the loom, by soldering them”. In Mk1 these appear in the cabin, behind the upholstery, behind the center console, also routing the turn signal switch, wipers, etc.

I replaced mine during restoration, here are the main things I did:
I took plenty of photos of the old one to show routing and attachment points. Before install, I laid the new one out flat to ensure there were no kinks, bends, or twists. I tried to label as many things as I could. And of course I had the wiring diagram within arms reach. Lastly, when I removed the old loom, I cut it rather than disconnecting it from every item. That allowed me to connect each wire in turn, replicating the routing and ensuring a one-for-one accounting.

Unfortunately my car had suffered a wiring look fire in the engine bay which ruled out all reference points you mention. I checked the archives for some info and photos but came up with nothing. Correct routing of wires under the dash appears to be critical due to lack of space and I would appreciate which ‘sub loom / extension’ should go where. I think when I have this area sorted the the engine bay should be manageable without difficulty. I do have the Coventry Motors Wiring booklet and Jaguar factory workshop manual.

Just did this about 6 months ago. I put the loom in before the engine which access easier, but no big deal.
The biggest lesson for me was trying to get the loom to ‘lay’ correctly both behind the dash panel and in the engine bay. You need to take your time and ensure you get it right. It’s a bit of a fight as the loom is stiff. I’ll see if I have any useful photos.
The individual connections are quite simple just the lighting switch and the wipers needing carefull reference to the terminal numbers.

Hi Phil, good to hear from you again ( Eugene ref the twin SU’s on manifold ),
Your photos will be very helpful. Maybe you might have a photo of the loom coning out from the bulkhead showing the fixed position of the pair of extensions going towards the centre of the car.

Hi Phil, due to circumstances I never got starting to rewire my Mk2 until now.
I had believed I had all the required sub looms as well as the main loom but have discovered I do not have the loom for the wiper motor. Have done a search on the net but unable to find anyone supplying this windscreen wiper system wiring loom, can I ask where you got yours so I could try them.
Thanks Eugene

Phil you may have seen I have been informed the ? missing loom actually exits from inside the car to the engine bay where the wiper driver cable enters inside of car so my concerns re the loom are now all alleviated. Great outcome.


I am going to try to install a new wiring harness in a mk.2. Unfortunately, the old one has been scrapped and the person who started it has gone cold. Should you be lucky enough to have someone lying around with some before and after pictures of such a project. Unfortunately, it will probably have to be completely dismantled again. Because it is not stored very neatly in the car.

Hope for help and thanks for your time here.


Send me a pm And I’ll send you all the photos I have


I can’t see where I can write a pm. Can you send me one. Maybe it’s because I’m a new member here.

Many thanks for the quick reply. I am a bit confused because the diagrams I have show different wire colors. So it would be a great help if I could see the pictures you have taken in yours.

Thanks again for your time and reply.


Jaguar always used standard wire colours, so it would be odd if your chart didn’t match them.

To PM click on Phil’s avatar and a pop up box ought to appear. Top right hand is the message tab.

I know it won’t help you now, but for someone reading this thread in the future, when you disassemble the wiring loom:

(a) take lots of pictures of how the wires are laid especially which wires go on top behind the dash and exactly where clips or metal tabs hold the wire in place and

(b) cut all the wires off the individual components, leaving 1" of wire and the Lucar connector so that you can see what colour the wire was for when you reassemble it.

I’ve wired a lot of E Type restorations and this saves you hours of trouble.


You are absolutely right that it is a really good idea to have taken pictures of the wiring before starting anything. But as mentioned, it wasn’t me who started it and therefore I am at a loss and must find the ways in which the old wiring has run in the car. I think there are diagrams for several different Jaguar models in the car. So there is only one way and that is to start over,

Cars have then been glass-blown and freshly painted, so luckily only the wiring is going to be a time waster.

Thanks for your input here. I will probably post some pictures that show from start to finish…

Hello in the forum.
Then I started to install the new wiring harness in the car. I have then found out that the car has previously driven with a minus to the frame. I then had to do that again as there was a plus on virtually all the wires in the car. Now I have a question.

When the car is switched on, it is so common that the brake light in the instrument panel lights up. I haven’t started the car yet as I need to install some new plugs and wires. It also works when you pull the handbrake to tell you that it is engaged.

The person who started the project has used red and blue cable lugs. it is simply sacrilege to mount such junk on a jaguar. There must be uninsulated cable lugs which are soldered and crimped, as was done from the factory. Then you can also be sure that there is always a stable connection.

Thank you for your time here, and as I said, I will probably post some pictures with descriptions of what I have and had of challenges.

All the best

Now I myself answer my question about the brake light that was on. It was because at the wiper motor there is a red green wire that is for the brake fluid reservoir. It was one of the wires for the wiper motor fitted in. This caused the wiper motor to become extremely hot and caused the lamp to light up. This wiring harness has obviously been made for both right-hand and left-hand drive cars. the one i’m about to make is left hand drive. There is a reservoir for brake fluid on the left side. it is the same connection that sits on the right side of the wiper motor.

Have ordered cloth wiring so I can make all fitted wiring look like the original wiring harness. There are some small challenges when you have not started the wiring harness replacement project yourself. but for now all buttons and instruments in the center panel work. lights and brake lights and taillights. So slowly but surely I will reach the finish line.

all the best.