Here ya go.

V12 ignition diagram.pdf

 

Ok,Need to know what the black wire that is in the same cloth harness as coax wire from ecu to ign power amplifier is for?There are only these two wires in this harness.I was told that the black wire was to be hooked up to outer shielding on coax wire.I did this and now I think I blew my ign amp.I use to have 12v on the coax wire hooked to amp from ecu with ign on.Since I hooked up that black wire to outer shielding of coax,I dont have any power comming out of amp.I dont even have Any volts comming out of tach wire.Amp is hooked up correctly to main coil.I still have spark to spark plugs.Please advise
Thank you

 

sorry grant,For some reason I cant open,the pdf file.I am using my Android for for internet.It says I cant open it.

 

Um, that is "no speak for me", as "IT" and me are the worst combination you will ever get.

Manyan IT item has bounced off the wall due to no operation.

I do remember having to "update" my PDF thingy when I got this W8 laptop, and many, many things are different, so my Jaguar alcohol now sits nicely with the laptop usage.

 

OK, one thing at a time.

That black wire is an earth, at the ECU in the boot, from memory.

Some I have seen have had that black wire earthed at the mounting bolt of the amp, but it looked after thought, not Jaguar.

That very thin wire inside the coax is simply a puise signal wire TO pin #18 of the ECU, thats all it does. When the ECU sees that pulse it activates the fueling circuits and the engine fires. That signal, I imagine, is much like a tacho pulse.

I have never measured the voltage in that wire, coz as long as there is continuity to the ECU pin, and no earth cross feed, the ECU is warm and fuzzy.

There are 2 resistors in that rubber blob, 1 is for tacho, and the other is for ECU, and I have read of some people having these blown, and engine dead, but I have never experienced it.

Spark is seperate from the fueling ECU. The spark is purely the amp on the LH inlet manifold, and the ECU is purely fueling, so as long as it sees that pulse via that coax wire FROM the amp the injectors etc keep working.

I would disconnect that black wire, see what difference if any.

I have attached an ECU pin out that I use regularly to trouble shoot these beasts, and it is for our market, so some of thr NOT used pins here may well be USED in other markets. It is a "Word" doco.

XJ-S ECU Pinout table.doc

 

Greg your PDF file opened up fine on my computer. If you click on it, it downloads then you open it with your pdf viewer whichever that maybe.
jagurnet
From your previous post, when you have cylinder 1A on TDC and the mark is at 0deg on the timing mark, the distributor rotor as you said should point to the 1A position on the distributor cap. Now this position if the AC pump is at 12o,clock it should be pointing to somewhere between 10.30 to 11.00 as the clock goes . To be a little more precise if you drew a line through the middle of the distributor button it will actually point to a position much closer to the 2A inlet manifold, If yours is pointing to the 1A spark plug I think you have it one notch out.
You can check this by installing your distributor cap , have the distributor basically centred on all the adjustments bolts and with a straight edge draw a line through the centre of the coil lead and 1A lead plugs on the cap, make a mark on the A bank side of the head, know that's where the rotor button must be pointing to.
Good luck Again

 

Katoh,

Well described, wxcept the rotor actually "points" to wards the "B" bank of the engine, BUT, the "1" cast in the dist cap post area is related to 1A spark plug and its lead, and the plug lead designation all starts from that key point.

It is confusing, and the A and B gets all crossed up very easily.

"A" bank is RH side sitting in the car face the direction of normal travel, and "B" bank is the LH side.

 

Grant
Thanks for picking up an era I made also, Your dead right it does get confusing and I too just made the same mistake, Bugger me! In my last post should read that rotor should point close to the 2B inlet not the 2A. I think its easier just putting up a photo and saying that is where it is and should be and leave it at that.
I apologise for any confusion.

 

I've brought this up before...be very afraid of the "new" crop of GM ignition modules. My car worked fine and when I "tuned" it up I went to NAPA and bought an echline GM AMP just to put a "new" one under the bonnet...wouldn't work, bought a Mallory...wouldn't work,...WELL's, same thing EVEN THE NEW DELCO/REMY didn't look right...the newer ones don't have the same grounding lug that the old style do when it comes to the "through screw" to ground the unit...think it works fine in a HEI distributor but not so much in our application...even the parts guy at two stores admitted there was a big difference once he saw them side by side. I opted for a NOS GM Delco/Remy one off E-bay and it's works great.

 

Thanks Guys,That is exactly,the way I installed dist.
I understand concept of ecu to amp and pluse to ecu for fuel delivery.my big Question is proper hook up of the tacho wire and ecu pulse wire.one sits to the left of the solid wht wire and wht/black tracer wire that go to main coil.other to right.(four wires total).Now leaning over driver side(USA left hand drive), using main coil as 12 position looking from above amp.The diagram Grant sent me of ign cicuit.It shows on diagram the far left wire(wht/slate) is for ecu pulse.The far right wire(wht/slate also)is for tacho.now on my car, with ign on (no cranking),the left wire comming out of amp has aprox 6 v.the right wire has 12v. my two wires are hooked up opisite of Grants diagram.thats the way i was told to hook it up.just want to be correct..

 

It's probably opposite of Grants because he's in Strailia!

 

Seriously!I know the toilets turn the opposite way,but wiring is oposite of ours...

 

Go to this thread read post 17, There is a photo and description of mine. Its on the left bank while sitting in the car.
https://www.jaguarforums.com/forum/x...-spark-117909/

 

well,Found out I must have a pulse from ign amplifier.I took off front two injectors left them hooked up to fuel rail,turned on ign and cranked it over, both injs were spraying with a pulse.
Im now thinking spark problem.I have good secondary spark comming out of coil to dist.now when I ground spark plug wire the spark is not consistent,iintermittent.So problem must lie in distributor somewhere correct?

 

Catching up, been at work, I really must retire again soon.

Lots of things move differently down here, and I have all sorts of issues with that when I go see the relations in Las Vegas, HAHA>

If you got good spark out of the coil, and so so spark at the plugs check teh following.

1) Carbon brush inside the cap. Many have been worn away and even missing down here.
2) The rotor itself. Many people "clean" the tip, which increases the "air gap" with the cap, and reduces the spark efficiency to the plug leads.
3) Plug leads. These cop a belting in the V, and resistance readings can be horrific. I use Magnecor ONLY, and never had an issue.
4) The park plugs, obvious reasons.
5) Engine earth strap fiasco at the LH engine mount.

 

Catching up again.

I dont think it makes a real lot of diference, but I may be wrong.

The original wiring from memory (that is rubbish at the moment) is that one of those pulse wire joiners was a blade style, and the other was a bullet style, and I THINK the bullet was the tacho.

Now, years down the track, and these terminals have failed (Lucas) and all sorts of make shift connectors have been used, which is great until you forget, and trust me, it happens.

As I said before, I have never measured voltage at those wires at the amp, never needed to.

 

Mate bite the bullet, go out and buy a new set of leads, plugs, dizzy cap and rotor button, while at change the two coil system to the new single coil that Jag recommends, that way you have gotten rid of all those little variables that could or may be the issue.
I use either British Parts International or Jaguar Parts | Land Rover & Range Rover Parts | British Parts UK for my parts.

 

Good advice,Thanks.I did change spark plugs and I did clean the rotor, contact points and carbon brush, in cap, with some sanding cloth .Also,I sprayed out inside distributor with carburator cleaner,because the reluctor wheel and pick up modual where a litle rusty,and dirty.That shouldnt hurt anything? I did not use sanding cloth on reluctor or pick up.what about gap on pick up in distributor,could it change?
Ill get new cap rotor and plug wires,cant hurt.
Also,can turnning engine over alot,without efficient spark cause the fuel to run down through pistons and into oil sump?

 

I'm inclined to say 'yes'.

But.....on the other hand...

I'm pretty sure the system has some sort of flooding protection provision. Can't remember off-hand how it works. My memory is foggy on that. Others will chime in.

Pull the dipstick and give it a whiff.

Cheers
DD

 

The reason im asking,when I bought car,I pulled oil dipstick and it smelt like fuel.I drained oil and a bit of fuel came out,oil was deluted.I changed oil and filter just a week ago.Now that I have been trying to start it every day,it does have a slight smell of fuel.So im not going to try to start it again,untill I know I have good spark.If I disconnect fuel pump relay ,I wont have to worry when I cank it to check for spark.Im going to take Katoh's advise and change cap, rotor and plug wires.I may have to get a second job,just to pay for the maintenance on this car..