Anyone here re-make fuel injector wiring harness?

Hello gents,
I was contemplating making a new injector harness but with all my projects will not have time until next winter. Is there someone on here who makes them with exceptionally better materials than original?


Memory fails me as to names. The "Hot Rod magazines usually have adds by two or three that off harness. And some make custom units.
I forgot the name of the one, a smaller outfit, that made extensions for the O2’s on my lump.

You will likely get better connectors. Not original Jaguar, but in your car, surely not an issue.

Your engine bay brings back memories from my childhood. Two older kids up the block were in to cars early on. Circa1941!! One car was an elderly Chevrolet coupe, circa 28 or so. A bit drab. So hey painted each body panel a different color. Same for the four 21" disc wheels.,

Then, wow, 12-7-41. they were off to the Navy…



There are some US based companies that offer new aftermarket harnesses for older cars. Two companies that I have used for my 1957 Jaguar MK VIII are British Wiring and Rhode Island Wiring. I have not purchased any harnesses for my newer Jaguars from them, opting to do minor repairs and connectorvreplacements myself. Seems to me they both offered harnesses for a wide variety of years and model of cars. Certainly worth checking them out.


I couldn’t tell you if it was exceptionally better, but SNG Barratt sells one for $400-ish!/English/parts/1c04adfa-ba49-47fd-afac-3f2e635f27d2?gt=Fuel%20Injection%20Wiring%20Harness%20for%20Jaguar%20XJS

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I’m too busy to be doing side work, but if you decide to try it yourself I can provide links to excellent sources for high temp GLX wire, high temp sleeving, connectors and boots.

Does anyone know of a source for compatible inj. loom connectors? I believe most DIY jobs just reuse the OEM plug as a pigtail.

1988 XJS V!@
I made my own with better wire, new connectors at the injectors and re-used the existing harness connector. I used a loom wrap that wraps around the wiring harness and allows for each injector connector to exist without cutting and tape. Looks really nice and only took about 3 hours. I tried to copy the existing but it was very brittle and actually easier to build on top of the engine. It now sits just above the valley and should last a long time. If interested I will locate the types of material used.

V!@ equals V12. Sorry about that.

On this new forum site, you can edit your posts, there is a little pencil-shaped icon in the bottom right corner of the post you may want to amend. Try it next time :-)))

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I am in the process of rebuilding my EFI harness also - 1989 XJS V12, Lucus. But I have run into a bit of a snag. I am confused about the polarity of the injectors. I have identified the colored wire (2 for for each bank that serve 3 injectors each; one for the odd, other for the even) and the two pink/black wires that do the same for each bank. The first question - are the pink/black wires the ground (-) and the colored ones the (+)? I saw a historical posts that indicated the opposite. The other question is how can I tell the polarity of the injector itself - it is my understanding that it makes a difference. My connectors don’t have a “+” indicating which side is positive, and couldn’t see anything on the injectors. I ran a continuity check on the old harness to ID which side of the connector was pink/black and which side was the colored. Assuming that the Colored are + and the pink black are - and looking at the connector face on with the clip “up” curved notch “down” I got:
1B - +
2B - +
3B - +
4B - +
5B - +
6B + -

1A - +
2A + -
3A - +
4A + -
5A - +
6A + -

I would have thought there was a more of a consistent pattern between the banks and the polarity would be the same for all. The car ran fine with the old harness in this configuration. I feel like I am missing something.

Insight would be greatly appreciated!

Injectors have no polarity. Connect it up whichever way you want.

great - and thanks for the reply!

Company in the UK called autosparks can make you a new loom… I bought an alternator loom from them this year.

I’m currently remaking an injector harness too. Still waiting on a couple of bits to turn up, and it’s been really cold and wet here, so I’ve sort of left it for a while.

Make sure you use the most high quality wire insulation you can find. I went with PTFE but it was a nightmare to find in the correct gauge in the UK. If you’re in the US there is a guy on ebay who sells lengths of it cut for a much more reasonable sum, but here it’s almost as if it’s 100m rolls of it or nothing.

On the 1991 onwards cars this is a bit more of a pain, the injector loom is taped toghether with some other wires (that weren’t there on the older ones) meaning you can’t remove the old injection loom that easily. I’m just going to run a second loom on top of it. Yours should be much easier to make neat!

Yes - thanks - I got some good wire from Del City - researched it and ended there. I am also running the harness from the back - on the outside/under the rail - out of the V - seems to make sense. However, you do have to pay attention to the 1 to 6 banks since they are now reversed fist wire off the harness is 6 instead of 1. I plan to put together the connectors and new end plug this weekend.

I think most of us route it in a similar fashion…or at least get it out of the Vee.

The high temp wire is great; I use it myself tho can’t remember the exact spec at the moment. However, I think most of the benefit comes from moving the loom out of the Vee.


PVC-insulated wire rated at 70C in the vee of an engine with 90C thermostats? What could go wrong?

I sorta disagree. IMHO, what’s most important here is getting wire rated at well above 100C in that harness. Getting it off the bottom of that vee is also handy, as things tend to get oily down in there. But I just raised mine an inch, supported at the level of the intake manifold gaskets, and that worked just fine. And visually it doesn’t look much different than OEM, a far cry from those cars where the injector harness is strapped to the fuel rail.

Might help. Original colors:

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I used ordinary wire, and strapped it to the fuel rail, worked out fine.

Hey Paul the diagram is great - Thanks! I am at a break - waiting for a connector. I ordered an Aptiv/Delphi GT-280 10 pin connector that I hope will do the trick.

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