PROBLEM SOLVED!
I picked up the XJ8 after I finished work today. The car started up great, and was driven home safely, about 35 miles. The engine performed great, could use a proper wheel/tire balance, but mechanically was in good "nick." The diagnostic, and repair time, cost me 2 hours of a discounted labor rate. They also checked other systems on the car and other ECM functions and there were no issues.

The cause of the no-start condition was......
"Immobilization" and was corrected by "Immobilization Reset"
So, indeed, the immobilization system (no injector pulse, no spark) can be a separately triggered event (with no codes) independent of the security system (no starter, fuel, or spark).

During this adventure, I learned a lot. I now know how to use more functions of the multimeter, purchased a fuel pressure gauge, and fuel injector noids, downloaded JTIS, and improved my understanding of the wiring on the Jaguar. And most importantly, learned that members of the Jaguar forums are always willing to lend a helping hand. Now on to fixing all of the other fun stuff that I have now...ABS / Stability Control Fail, Washer fluid low, and rear bulb fail.

Thank you to everyone for all of their assistance, suggestions, motivation, and encouragement in getting to the bottom of this matter. We have helped one Jaguar live to see many more days!

 

Good to hear!
Could the code be reset by a snap-on scanner, or is it jag tech specific?

 

Well, we've all learnt something not least that these cars really are too complex for their own good.
Certainly not to be relied on to cope should the End of Civilisation as We Know It come along!
Glad you got fixed after a long fight, rather sad JF couldn't do more than jolly you along.

 

I'll DRINK to that!---milk of-course*

 

Did they give you any indication as to what caused the immobilization system to activate?

 

Really glad it was nothing major!!

 

In order to perform immobilization reset, you would need to have access to WDS dealer type scan tool, which is available used online (when you can find it).

 

Unfortunately no direct information of what had caused the immobilization to be set and the Jaguar tech is very hard to reach. In my opinion, it could have been a number of factors, particularly the poking and prodding of the car's electrical system prior to my ownership, battery dead for an unknown amount of time, or other issues related to the car sitting around.

The dealer description is the standard wording:
Checked fuel pressure - OK
Checked fuel injector Pulse - None
Checked spark - None
Checked ECM to ground and high resistance + - OK
Immobilization Reset performed - CAR STARTS

 

I feel that the car has a history that caused the Immobilization. It could have been from a repo and a new key was made and was not programmed, the car being towed or a simple intrusion. With that being said I am pleased that it is now running and you can have fun with it.

 

ignition coil relay!

you probably have cylinder wash from trying to crank it over too much.

try both! good luck. I took the relay from under my back left seat (fog light relay) and put it in where my ignition coil relay had gone bad.

 

Nope, tried all that, it was immobilization reset that corrected the problem.

 

I say "Ambiguous" only because the No Crank Conundrum has so MANY possible (& seemingly) DIFFERENT Causes ...
Sarah provides what info that She CAN, but it's "anecdotal" & I realize that's problematic ... Here's what I do know about this 1998 Jag XK8 Roadster;
1. Batt was/is new ...
2. As the condition began, it became infrequent & progressed to ultimate refusal ...
3. The Key & Exciter have been eliminated as causal factors ...
4. She tells me that during the run-up to Failure, She would open the trunk, tap the Batt Terminal, whereupon She'd hear a "Click, Click" at the rear of the car ...
5. Car has been meticulously maintained, never wrecked, not a "Prior Flood" Car, nor Repo ...
6. Note that the car is in Western Colorado & experiences Summer & Winter Temp Extremes ... She tells me that She doesn't drive the car during winter, when it is garaged at her home ...

The FORUM discussion & my experience inclines me to suspect the Starting Relay as the culprit. Obviously, I seek Your Collective Wisdom &/or Experience ...

 

Sorry; I neglected to mention that ALL OTHER Electrical Functions ARE Operational, and the SOLE problem is that the Starter Unit does not operate/function. Having owned & operated XJ6, XJ12, Norton 750 Atlas & a Rover 2000TC(!), I would THINK the Start Circuit would be Fuse protected ... Circuit Breaker & Relay would seem Logical ...

 

If you have another ignition key, try that. If the car does not even attempt to start up, but all the dash lights up, there is a good chance that your car has been immobilized and may need reset at a Jaguar dealer or use of WDS program. It may also be worth pulling the diagnostic codes from the car. There is sometimes a code that clearly indicates if a car has been immobilized.

 

Drove car all day, Pulled into my Father in laws drive way turned car off. 15 mins later, tried to start and it would just turn over or would run very low RPM until it died out. No lights or codes. used Diagnostic tool, No codes. Fuel Rail sprayed me when I pushed on valve. Fuel pump is about a year old. Need help

Thanks Vince

 

Try to put the shifter in the “P” or “N” position then give it a try.

 

It sounds like a crank sensor issue to me.

 

yeah, but wouldn't i get a code?

 

What year and model???

Some do trigger codes, some don't - The one's that don't are usually mechanical, the ones that do are usually electronic issues

There's a loss of signal to the ECU when it doesn't start - from either coolant temp sensor, crank sensor or cam sensor. These all tell the engine it's good to introduce spark and gas, if it doesn't get a full report back it inhibits fuel, and or spark which can lead to big headaches. It's down to your investigative skills at this point, and any info on what it's doing with your efforts to start it.

 

1998 Jaguar xj8. The last time this happen it was a fuel pump ( fuel pump has about 12K miles on it). It's still under warranty. I was just going through anything else. Won't start, no fuel in fuel rail. Fuses in trunk are ok, I switched out relay. Battery seemed good. No codes. Will crank but not start. Checked inertia button on passenger side kick panel. If you shoot starting fluid in carb it will start up run rough.