Based on my wiring harness, I think my 11/87 car is a MY 1988 1/2, as the brake light switch passes 12v current from the battery through to the brake light relay, while the earlier car/harness used the brake light switch as ground for the relay coil, current flow reversed, basically.

But, supposedly the '88 1/2 MY cars had 4 speed 4L80E trans per the Jag repair/specs manual. My car has a 3 speed TH400.

Onto the wiring schematics. They don't match reality, this is obviously a factory harness, but some colors codes don't match what is there. also, extra or missing wires from what the schematic shows. Not many, but some, such that is makes component ID a little tricky. Kind of half-assed way to do things, i wonder if changes were made on the fly, or they ran out of certain wire colors building a few harnesses, or what, or the documentation is wrong.

Just general venting.

 

No, the V12 didn't get the 4L80E transmission until the introduction of the 6.0 liter version.

As for your understandable frustration, you've just got to keep in perspective that your car is somewhat unique -- It left the factory and was sent to H&E, they made changes to many things including some of the wiring, then it was owned by a least one person who was... shall we say creative, and who knows what kind of changes they might have made including possibly using a different harness or replacing wires without regard to color coding.

Hang in there, you'll figure it all out.

 

I don't what you read, but the 4L80E did not get used until the 6.0 came out in the early 90's. The 3 speed TH400 was used until then.

Jon

 

Right in the official Jaguar XJ-S Repair and Operation Manual, published by Jaguar cars, Ltd., it lists the specs for the 1988 1/2 (and up) XJS as having a 4L80E, and they list engine size as either 5.3 or 6.0 L, with 6 L in the 1992 and later cars

One would think, they would get the correct info in their own repair manual. Or at least make it more complete (or less confusing) by saying the TH400 is used only in the 5.3L cars.

Doug

 

Doug,

Show us that page from an official Jaguar Manual and I'm sure we'll be able to sort out the confusion. I have a lot of the Jaguar documentation and I've not seen a doc that says that an 88.5 MY has a GL480E.

As regards what MY you have, the changepoints are at defined VINs ( as built at the factory) H&E converted cars can confuse things, but basically if your car is after VIN 148782 it should be an 88.5MY

Cheers

Paul

 

My VIN is 146775, so that says pre 1988 1/2, but if you look at the ECU and trunk pics I posted in another thread, they look different than the ECU that Sanchez has.

https://www.jaguarforums.com/forum/x...people-274770/

Compare ECU in post #8 (Sanchez) vs post #9 (my car)

And again, my wiring harness matches the '88 1/2 schematic.

So, who knows?

I will take pic of that page in the repair manual and post it later. I know i have TH400, I am just surprised the manual was sloppy about their printed specs.

Doug

 

Do you have one of the manuals with a green cover? Looking something like this?



If so, that's one of the (very commonly sold) service manual compilations which incorporates selected sections from various other Jaguar factory service manuals. And, yes, sometimes they are not properly organized and/or edited.

But, beyond that, yeah, a lot of the factory tech literature simply isn't all that great compared to the best I've seen. It takes some getting used to. I suspect this plays a role in the "difficult to repair" reputation these cars have had for decades. The factory TSBs are usually quite good, tho.

For wiring I recommend Jaguar's S57 manuals. I can send the XJS verson to you if you can't find it online. Also, I'm 99.99% sure that Jaguar published a supplemental manual for the H&E cars. Someone here will know, or you can try some Googling. It would (hopefully) show any wiring changes unique to the H&Es.

Cheers
DD

 

That is the manual i have I am referencing. Supplement C, page 2, titled 1988 1/2 XJ-2 5.3l and 6.0L

I will look for one online, at a link that works, I found one link, but its no good.

Doug

 

Here's one

Hess Eisenhardt Jaguar XJS XJ-S Convertible Shop and Parts Manual - Brand NEW! | eBay

There's a webpage that has a jillion Jaguar manuals to download. I can't remember the name at the moment but someone here will. You can probably find the H&E book there for just the price of a donation

Cheers
DD

 

Already have that one on .pdf. Helpful, as it has some simpler elect schematics, but its not all inclusive.

I downloaded the S57 from a place in Czechoslovakia.

Doug

 

The original ECU for MY 1988 was a 6CU and I upgraded to a 16CU because of the inherent problems with the fuel pump circuit with the 6CU. My VIN is 147806. I use the electrical schematics for 1988 and 1989 XJS to help me with circuits that looks wrong on one but correct on the other. If you need the schematics for both years let me know.
The electrical system on your car is not as bad as you are making it out to be. I am of the opinion that the PO did some electrical hacking because he did not understand the schematics.
It took me years to understand the schematics and like you I cursed at Jaguar and Lucas until I realised that it is not so difficult. Painstaking? Yes.
The GURUS on this forum have helped me a lot in understanding the various systems. They will show up eventually. Don't give up. Start by removing any hacked circuits the PO did and use the schematic to trace your circuits. One by one.
If you need a 16CU for your car let me know I have 2 extra ones.
The sticker on the ECU will tell you whether it is a 6CU or a 16CU. Physically they both look the same.

 

Doug,

I'm intrigued as to whether this is actually a document produced by Jaguar rather than one compiled by an external company that has pasted together various Jaguar content. The reason I'm confused is that:

1. There's no such thing as a 6.0 XJ-S. The only 6.0 models produced are XJR-S (pre-facelift and facelft) or XJS (no hyphen) facelift models.
2. Even the 6.0 XJR-S wasn't produced until 1989 MY

So the idea that Jaguar themselves produced documentation entitled "XJ-S 6.0 V12" seems quite strange? Is there a formal Jaguar document reference number for the manual that you have?

Cheers

Paul

 

I have an earlier edition of the manual shown in my posting above

The title page states "Published by Jaguar Cars Ltd. Publication part number AKM 3455 Ed 4/3"

(Without going into excruciating wordiness explaining what is written) both XJ-S and XJS appear to be used without discernable rhyme or reason whatsoever....although I'll confess that I didn't labor very intensely on this; its not a hill I intend to die on

The Supplement C is confusing. No surprise, as the layout/logic of the entire publication isn't very good.

The first chapter of supplement C is "6.0 Litre Engine 1993.25 Model Year On". The second chapter (one page later!) is "Emission Control System 5.3 Litre 1992 Model Year On". The title page of Supplement C mentions "1988½-on" but all of the following chapters and text references only 1992-later cars.

This is rather typical of these green book Jaguar manuals. I have several. They're all a bit of a hodge-podge but with some patience (and some previous Jaguar knowledge) you can eventually find what you need

Cheers
DD

 

<< This is rather typical of these green book Jaguar manuals. I have several. They're all a bit of a hodge-podge >>

I don't think this is just a Jaguar thing. LOL. These aftermarket service manuals can make you a little crazy if your vehicle had a lot of different possible motors, variations, or just a long model run where they made lots of little changes over the years. The Jaguar effect may be enhanced by Jaguar's parts department not really having any awareness of the parts catalog before ten years ago.