No repo car, they usually come with the bank paperwork and need to be disclosed. The key is what appears to be an original, but not too beat up.

I had a bad key on my XK8 that I needed to get programmed at the dealer. However, when I had that problem, I couldn't even get the car to turn over.

The exciter ring sounds "exciting." Would an issue with that ring still allow the car to turn over, activate fuel, but not provide spark?

 

I am not 100% on it but I think it does I recall another car (S-Type) that had a similar problem.

 

Gus - if he can lock/unlock the car with the key doesn't that mean the key is 'paired' to the car or can that be OK and the second check when the key's in the ignition fail?
FWIW (not much) on an XK nothing works (fuel pump, starter, ignition) if the key is bad.

 

The exciter ring is only located at the ignition key area so if the key is keyed to the car it will lock and unlock mechanically all the locks. The exciter ring reads the transponder once the key is inserted into the ignition area to start the car. I had “0” hands on with the exciter ring but I think it is worth checking.

 

Last night, I took the driver rear door panel off, and checked the door module for any obvious signs of damage. Nothing visible, but likely a short somewhere internal.
In an effort to resolve the U1135 mentioned above, I just ordered a replacement rear driver door control module, it has been shipped out already. Hope to get it soon. I just want to make sure that I can eliminate the possibility that an incomplete circuit throughout the car is not the problem causing no start. If I pop in the door module, and the U1135 code goes away, at least I will have fixed that problem anyway. From looking at a "input/output" chart in JTIS, the rear driver control module has output into the BPM, and the BPM has input into the ECM. You just never know with these cars. If that module does not do the trick, I will try to focus on the ignition area and exciter part.

Tonight, I plan on doing some more diagnostic tests of the BPM (based on JTIS procedures) just in case there is something in there that is at fault. Also, I will check into the ignition switch area.

As of now, I still have U1135: SCP (J1850) Invalid or Missing Data for Ignition Switch / Starter for the rear driver door control module only, even after repeated clears.
I have 40psi fuel, fully charged (new) battery, new plugs, relays good, 12v at the coils, still no spark on any coil/plug.

I am not reading to wave my flag in surrender yet, but I have a stick ready, just in case.

 

Here is a list of possible causes of the code I have. I find it strange that it is only on the rear driver door module, and not any other module.

U1135 Rear Driver Door Control Module

Fault Description: Ignition status (ignition switch position) not obtained.
Possible Causes:
-Ignition switch to BPM switched ground circuit(s) fault
-BPM SCP Key Status error
-BPM SCP network fault
-SCP network fault

 

I'm sorry to see you struggling here.
I notice you had a 1638 code before changing the ECM, now you have
U1135: SCP (J1850) Invalid or Missing Data for Ignition Switch / Starter
There's a good thread on that code here
https://www.jaguarforums.com/forum/x...41-help-64099/
so I don't think it is relevant.
What you need is Brutal - a man of few words often with caps lock on but knows his stuff.
I don't know how to tempt him to appear - perhaps posting a new thread on the lines of '18 year old nymphomaniac seeks Brutal Man' would work.
Don't give up but the replacement door module isn't the problem.
Did you check, BTW, that the resistance on the replacement ECM was correct?

 

I will check into all of the ECM pin tests on the replacement ECM tonight. I also plan on checking out the ignition exciter coil and the BPM. That should keep me busy through the weekend. I can't wait to hear it roar to life.

 

I found this useful information (although for a 2003 Jaguar XK), it describes the operation of the starting of a Jaguar in greater detail. This may shed some light on ignition issues for my problem, and for others.
I am encouraged by the last bullet point under the "Engine Cranks but will not start" section. It mentions checking ground of the (key exciter) coil when in crank position. I have not done this yet. My car's problem can run, but it can't hide. We are on the hunt, I feel a victory near!

System Functionality
The immobiliser system prevents an unauthorised attempt to start the engine. The Key Transponder Module (KTM) transmits a valid key status only after an authentic data communication has been performed between the KTM and the transponder key. When the key is turned to the Aux ignition position, the KTM energises the coil, which in turn starts a data transfer with the transponder key. If the code received matches a codestored in the KTM EEPROM, the KTM will perform a challenge / response routine with the key to determine its authenticity. Once the KTM has authenticated the key code received, it will send a “Key Valid” message to the BPM via the dedicated ISO Data link. If the key code does not match one stored in the KTM memory a "Key Invalid" message will be sent to the BPM. The BPM will transmit the SCP – key valid message containing a unique 3 byte number to the instrument cluster, the cluster upon receipt of this message will compare the data received against the unique number stored in its memory. If the comparison matches the instrument cluster will set a flag to confirm valid key received. If the comparison does not match the instrument cluster will set this flag to Invalid. If the key is turned to the ignition Run position, the instrument cluster will start the CAN data exchange and start transmitting the idle status. If the key status is valid, and the subsequent challenge / response is verified by the ECM, the ECM will allow the engine to start. Otherwise, starting of the engine is disabled. The ECM controls the following outputs: starter relay, fuel injectors, ignition coils and fuel pump.

IMMOBILIZER SYSTEM (Cont.)
XK IMMOBILIZER SYSTEM FUNCTIONALITY
The ECM will disable the fuel injectors, ignition coils, fuel pump drive and starter if any of the following conditions apply:
•A theft signal has been received from the IC, i.e. the key code has not beenreceived/code does not match.
•A challenge code has been transmitted to the IC but no response code has beenreceived.
•A challenge code has been transmitted to the IC and an incorrect response received.If any of the above cases apply, the ECM will log DTC P1260. This DTC is further defined by sub-codes. The sub codes are accessed through freeze frame data. Additionally, the IC will log DTCs if the failure was a result of the key transponder exchange.

IMMOBILIZER SYSTEM (Cont.)System Diagnostics
Engine Fails To Crank
•The most regular occurrence for failing to crank is due to the Park & Neutral startswitches, that is, gearshift not in Park or Neutral. The starter relay configuration is asfollows: low side of relay coil - switched directly from ECM (if conditions correct) highside of relay coil - direct from transmission P/N position.
•Other likely causes maybe that the CAN / SCP network is malfunctioning, i.e., the CAN circuit is open/short. This would mean that the IC/ECM or IC/BPM would be unable to communicate resulting in no authentication being performed to enable the ECM.
•Transponder key may not be programmed, or the KTM has not been taken out of build mode etc

Engine Cranks but will not Start
•If the Engine is cranking it means that the ECM is enabled with respect to the immobilizer function. If the immobilizer had failed validation the ECM would not engage the starter. This could be confirmed by reading DTC from the IC and ECM.
•In this case, the fuel pump circuit should be verified. A fuel pump module, which is controlled by the ECM, supplies the fuel pump.
•In all cases of suspected immobilizer non-start issues, the most logical failure modes should be eliminated first.
•Check all relevant supplies and grounds to the KTM, BPM, IC and ECM, check that the starter relay has a permanent 12V supply, check that the relay has a 12V supply and ground across the coil while the ignition is in the crank position.

 

From that it looks like the 'security' side of things is irrelevant since it cranks + pumps.
No fault can hide from JaguarForums !!

 

I just ordered the ignition exciter from Jaguar, about $40, it should be here Monday. I will try that.

If I don't find anything this weekend, and exciter doesn't do the trick, I have scheduled a tentative Jaguar diagnostic appointment on Wednesday.

I will keep posting updates of what is found. I am excited about the "exciter" prospects!

 

I admire your enthusiasm ! Some people might just get a little frustrated. The exciter sounds like a good possibility though. Best of luck.

 

It's nice to be surrounded by a group of Jaguar enthusiasts to encourage me along the process. Owning a Jaguar is definitely more of a relationship than just owning a car. I have never been one to back down from a fight with a car, and the Jaguar has definitely inflicted some strong punches. My technical experience is average, but I am learning a lot along the way. I'm 32 years old now, but maybe when I get old, I will look back and laugh at how easy it used to be to work on these cars.

 

Ok, another update. I have also determined that I have no injector pulse. So, I am down to the following issues:
No Spark.
No Injector Pulse.

 

I used justanswer.com and was connected with Richard, a Jaguar mechanic. He provided some additional diagnostics for me to check and got me to the point where I could exclude many other variables. Primarily, that the shifter solenoid was not an issue and that fuel injector pulse is not present.
Here is the link to the discussion:
Jaguar XJ8: I have just purchased a 1999 XJ8 at auction as - JustAnswer

I also removed the steering column trim, and checked resistance on the exciter ring, it is 34.1 ohms, in line with what I have read on another post. I have an exciter ring on order, and it should be here on Monday, just to try it out.

So, it looks like the immobilizer issue is still hovering as a possible issue, even though starter will engage.

 

Well I sure wish you the best of luck, I bought the exact same car (if yours is a Vanden Plas) on Saturday at an auction, but I drove mine home. If I could help, I sure would....

 

Good taste in cars, Corvette and Jag owner here too.

 

This
https://www.jaguarforums.com/forum/x...r-pulse-56922/
might help, post #2 has a useful link - maybe you've already found it.
I know you've replaced the crank sensor but can you check to see if it is working ?
It seems to me that would account for no spark/no injector pulse.
It may be that getting an rpm reading on cranking means the sensor is working.
Here's a troubleshooting guide
http://www.permoveo.ltd.uk/tabid/122...r/Default.aspx

 

Thanks, I had not seen that post. I will look into it tonight. The comment about "input signals to the ECM" seems to support the possible cause of the issues my car is experiencing.

 

FWIW (and I do go on about this) Don't use the Forum search engine.
Do use a very carefully worded Google search - it often points to hidden gems in our forum.
We all want to hear your engine roar into life so there's a lot of good will on your side.