Proper wiring Diagram

Good evening everyone
I’m tried looking for a topic or thread on where to get a true colored and accurately labeled wiring diagram in this site… My son a I are reviving our 86 XJS. We have completely dismantled the upper parts of the engine,ie; intake mani’s , all hoses, rad, and front brake system ,etc.They are either being chromed or polished. I took quite a few pictures to make sure we assemble it back together correctly( me being a mechanic,I learned the hard way)…Unfortunately some wires are broken and don’t know where they went. I’m replacing with custom made wires. I can’t for the life of me find a very accurate wiring diagram with either color or complete description. In specific there’s a green and I think white or yellowish wire coming from the side of the tranny. Don’t know where it goes, among some other wires. If anyone has a 86 XJS, I would greatly appreciate you lifting the bonnet and peeking in…LOL
On a side note does anyone know why my V-12 did not come with pollution pump, egr and cold start injectors? I live in Ontario Canada, I thought it came with all these emission controls? It has never been tempered or dismantled by anyone. I am the second owner and been reparing since it has 70,000 klms.
Thank in advance

Hello Pete. I have a complete set of shop manuals with wiring diagrams. Is your 86 the same as 88 1/2? I should be able to make copies for you. You can email me at Dave.

PM your email to me and I’ll send you the “S57 Wiring Guide”. It’s very helpful although it covers USA-market cars…which might differ a bit from what you have with respect to emission equipment

None of the HE V12s had EGR that I am aware of. As for other emissions equipment, well, there were many build variations depending on year and market. I doubt that any of us have fully documented (or even learned!) all of them

Cold start injectors were deleted circa 1984


Sorry for the late reply gentlemen
Wow you guys are incredible and quick. I was just in the garage with my son dismantling and cleaning the alternator. My email is I’m not sure how different an 86 to 88 are, but as Doug mentioned these boys did not care at all for conformity. Thank you for that insight on the XJS, Doug. I know Jag were brutal with non-compliance but this is insane… O well makes are days and repairs very exciting.
Thank you so much i hope i can repay you some day

Doug and David’s wiring diagrams should have been a big help. FWIW, the wire from the side of the trans. should operate the kick-down solenoid, and it hooks up to a microswitch which is hidden below a square plate at the end of the accel. cable. Green wires in photo.

Dave. I am surprised to see that you don’t have hose clamps on your injector supply lines. Is this normal? I’m sure that mine would leak w/o them. Special hose? Dave.

On the HE V12 the fuel nipples are barbed. The hoses are a press fit, so to speak. If the barbs are in good shape no clamps are needed…nor were they originally used.

Earlier V12s had non-barbed nipples so clamps were required.


You guys are the best… I’ve been a licensed mechanic for 40 years and I thought I knew some poop, but you guys make me feel like a first year apprentice, figuring out how to do an oil change…LOL. Dave i’m with you on the no clamps but we all know about under hood temps and rubber… If you the super cool and diagnostic look, go online and find an aviation supplier. They sell high temp, no fading, no kinking clear fuel line… I use this for all my projects especially my jetski… I still use the high temp, UV rated tie straps for low pressure lines… Just in case…Their about 1/16" wide by 4" long. I just opened my emails. Thank you so much gentlemen.
I know this has been asked somewhere in the forum but what do you gentlemen think of a good electric fan. My yellow plastic is broken and I do not want to pay $200. ca. I rather put it towards a higher volume electric.

Old dog learned new trick. Thanks.

Doug nailed it. As usual!

Oh boy, everyone has their own opinion on this subject- mechanical v electric. My own personal opinion is this- Most of my driving is highway and very little time stopped in traffic. The black replacement plastic fan is more than enough for me. If I had a lot of city driving I would consider using an electric set-up, but I really don’t need more than what I already have. ( Plus the fact that my alternator was replaced right before I bought the car, and works just fine.)

The factory never published a colorized diagram. I’ve colorized a number, and made my own diagrams, as well as have an un-finished version of the 87-88 elec diagrams. The section I have finished is for 87’ and that’s very very very similar to your 86’ car (88 differs in some minor ways + diff relays).

In combination with the full 87-88 elec diagram from or in the files section of the XJS Owners Group on Facebook, here are the colorized pages I’ve done for 87’. I can’t do them as one item because the 24 pages are too big as a single PDF to upload and don’t zip into anything smaller.

Fig_2.1.c.pdf (294.9 KB)
Fig_3.1.c.pdf (303.1 KB)
Fig_4.1.c.pdf (297.7 KB)
Fig_5.1.c.pdf (244.6 KB)
Fig_6.1.c.pdf (157.7 KB)
Fig_7.1.c.pdf (294.7 KB)
Fig_8.1.c.pdf (790.5 KB)
Fig_9.1.c.pdf (645.7 KB)
Fig_10.1.c.pdf (342.0 KB)
Fig_11.1.c.pdf (322.3 KB)
Fig_12.1.c.pdf (204.8 KB)
Fig_13.1.c.pdf (178.0 KB)
Fig_14.1.c.pdf (147.7 KB)
Fig_15.1.c.pdf (240.3 KB)
Fig_16.1.c.pdf (148.5 KB)
Fig_17.1.c.pdf (210.4 KB)
Fig_18.1.c.pdf (222.2 KB)
Fig_19.1.c.pdf (285.6 KB)
Fig_20.1.c.pdf (260.2 KB)
Fig_21.1.c.pdf (196.1 KB)
Fig_22.1.c.pdf (257.9 KB)
Fig_23.1.c.pdf (191.4 KB)
Fig_24.1.c.pdf (618.8 KB)
Fig_24.3.c.pdf (687.0 KB)
Fig_25.1.c.pdf (638.5 KB)

Additional diagrams/pics I often post to help folks:

(Almost correct diagram. The pinout is correct but the connector actually comes in on the other side, so mentally flip top and bottom for the actual view you’d see…)

79-87 5.3L Engine Harness Colorized v1.0.pdf (287.0 KB)
79-87 5.3L Injection Harness Colorized v1.0.pdf (289.3 KB)
79-87 LH Forward Harness Colorized v1.0.pdf (312.9 KB)
79-87 RH Forward Harness Colorized v1.0.pdf (430.1 KB)
79-87 Anti-Stall - Wash-Wipe Harness Colorized.pdf (281.2 KB)
79-87 LHD 5.3L Bulkhead Harness Colorized v1.0.pdf (460.3 KB)
79-87 5.3L Rear Harness Colorized v1.0.pdf (295.2 KB)

~Paul K.


HOLY POOP!!! that is incredible you are a beautiful man Mr. Kobres…Even with the beautiful supplied PDF from Doug, It does not show some wires and colour identification. I will try to take some pic’s… I thought I love my jag, but you guy’s put me to shame… What I’m really excited about is my 18 year old son loves also. We gave the car to him as birthday/graduation gift.


On the front injector hoses I added clamps because they are bent into a curve and the natural stiffness of the hose fights the fittings… It would be nice if there was a moulded hose for that use.

I concur.
And the black fan is the same with the Range Rover P38 2.5 diesel (BMW engine), aftermarket fans are good and inexpensive. And with a new Hayden 2665 Standard clutch you are set for life.

Plus, with a good 20A electric fan you will need those extra 20A form somewhere, and if you have the 75A alt you don’t have them, i.e. new alternator…

An by the way Dave, what is that funky solenoid at the throttle pedestal ?

Aristides, the funky solenoid was something that GM used for many years to set the idle speed. I was just playing around with the notion of not increasing the idle airflow with A/C. and using this instead.
I ended up not using the solenoid pictured (untidy looking) and went back to the original idle air solenoid idea.

This thing is plumbed into the hose running below “A” bank intake manifold, and is adjustable.

The adjustment scheme is even funkier!

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Good morning everyone, I apologize for the absence in response. I found a company in the states that sells spools of colour coded wiring, (open ends)… My son and I have been rewiring anything remotely cracked or worn. Since I’m also running all the wiring behind the engine so you see nothing but chrome or highly polished intakes and injection rail. I switched the temp gauge sensor to the left water jacket and the ECM temp sender to the right. The Ignition module and injector pack are now located at the front of rad for cool air… Everything is clear hose, water, vacuum and fuel…I just want to thank you very much gentlemen for your incredible assistance.

Pictures please!
20 char