Hi!!! So Im having an unusual issue getting this 2004 Jaguar XJ8 to start. This is probably some weird electrical/security issue, or possibly something else? Its an no crank no start, when I turn the key to the Start position , I put a volt meter on the starter and turned the key to the start position, and nothing happened at all, no voltage, just silence . However, I can get it to turn over when jumping the starter with a screwdriver and the ignition in the on position (I didn't try it in the off position though I'm not sure what that does...yet?)? I don't get it, there's power there, but the starter doesn't respond with the key on start? Anyway, when jumping the starter it just struggles to start but never makes that sweet combustion sound. Just - turn, turn, turn.... I most likely need to charge up the battery. Its had a lot of in and out movements over a month and no charge, but its also able to move the windows easily and doesn't really seem weak. Also, I would think being a jaguar it wouldn't be that easy, or safe......

My main concern is messing up electrical things. Like.... after jumping the starter with a screwdriver the brake fault warning came up.. oops
I'm really just trying to see if the car even runs before investing anything into it, and to do that I just need to see if the engine can run, and the transmission can move the car around a bit. Without blowing up too much stuff!!
Some fun facts about the car though:
I don't have the factory key.... Its an after market key....and can not unlock the trunk...Which makes me think its only a valet key
Air suspension and most of the supporting suspension is messed up and needs replaced.... Has a Vehicle is way way way to low warning
So I'm basically looking for a way to start this jag up old school style, just for testing it out,
I cant really go out and buy a new starter, or new spark plugs, and stuff to test out, because parts costs for repairing just the suspension, rims, etc already cost more than KBB value. So it may just be scraped at this point, I'm not sure yet.

Any thoughts on:
The guidelines on jumping the starter on a rear wheel car like this? And safety... I have the front on jack stands with the rear wheels blocked off, and its in park of course. Is that safe though, especially with brake fault....??? I don't wanna get mushed!
Whats a brake fault? Did I blow something up Jumping the starter? Should I not be doing that?
Any security features that would prevent the car from starting with the key ( even when I don't have a security fault message)?,
Why the key works fine for locking/opening the doors, but wont get the starter to turn the engine when turning the key is turned to the the start position?
Why the starter has power and can be jumped with a screwdriver in the on position If the key is the issue? Or do starters spin regardless of jumping and key position?
Where is the starter relay? Do they even label in Britain!?
Would jumping the starter even allow the rest of the computerized system to start the engine?
Would the fuel pump even spit out gas, if the starter was jumped without the key moving to the start position, and just staying in the on position?
What would Jesus do?

 

I've moved your question from General Tech Help to X350 forum. This is the place to post technical questions about your model.

Graham

 

I had a similar issue on an 2001 XK8 and it appeared to be a bad ground to the ABS Module. Everything on the car would work but would not turn over. Messed with the ground leads near the ABS module and it has now been working for some time. Caused a CAN BUS problem.

 

thanks for the reply! I checked around for lose or broken grounds, but I didn't see anything. Was the ground bad on the connector to the ABS module, or the ABS board itself? I would think that it would still start with a bad ABS ground if it were jumped from the starter, but then again this is the most difficult no start issue Ive ever had. This car definitely has some issues with over engineering, and expensive broken that could be anywhere and everywhere.

I still cant get it to start. I got a new battery because the old one was bad and wouldn't hold a charge. It has more power and more things work like the alarm, and a humming in the throttle body too. I'm guessing its computer controlled since there is no linkage to the throttle body. I don't know if thats OK or if its not working right? Im hoping its not stuck close or anything, that might explain it, Ill have to open it up and see. I still am stumped on how the starter is good , the battery is good, but the key wont make the starter turn. I cant find the stater relay location, I searched the www but nothing. Also nothing is labeled in the car, so even if I'm looking in the right fuse box, I cant tell. Not cool Jaguar! Jumping the starter doesn't work either to get the engine started - like its not getting fuel, spark, or maybe air in the chamber? Im not sure if its a security issue? I saw a post though where someone claimed jumping the starter worked fine on their 2004 JX8 with no issues.....

https://www.jaguarforums.com/forum/x...t-turn-134530/

I just want to get it started, I'm not sure what approach to take at this though. I think its an ignition issue, blocking the starter, (relay or security fob chip?), but then there might be more preventing it from starting too, engine wise.

 

Rather than risk damage to the throttle body maybe find a competent tech to figure out what's wrong elsewhere.

 

Thanks JagV8, But this car will end up at a Junk Yard before the Jaguar dealer, or a mechanic. Frankly they would charge more than I paid for the car to even look at it. Also a throttle body is simple to inspect, remove, replace, etc. It doesn't even have to be removed from the vehicle to see if its opening or closing, It would be highly unlikely I could do anything that could damage it.

 

What I really need help with is specifics on this vehicle. I really need the starter relay location, schematics of starting system.

The issues i've found so far is:
What appears to be a pinched metal hose line underneath drivers side of car (probably a fuel line)
slightly bent radiator (still holds fluid, don't think its related to no start though)
humming in the throttle body (Possibly stuck wide open or closed?)

Other concerns:
Spark? How to even test that without the ignition working properly I don't know ( pull some coil packs and jump the starter? I'm not sure if that would even work?)
Compression - who knows.... Probably good?
Fuel pumps.... I think there are two? How to test that they are working? I'm not sure

I can rent a fuel pressure tester, compression tester, get the starter tested, but the ignition issue is what is making some tests more difficult if not impossible . Someone out there has gotta have some info on the ignition system. This is the first car I have come across which has absolutely no information on something so simple.

 

You will find the electrical guides here JagRepair.com - Jaguar Repair Information Resource

 

And the whole workshop manual is a free download.

 

Brilliant! Thanks for the link Norri! That's just the kind of info I needed! I'll have to do some more research on this one, but based on the schematic I'm already thinking its a PATS (Passive Anti-Theft System) Issue not sending the signal to the ECM (Engine Control Module) then to the starter relay, or that the ECM isn't sending out a signal for another reason I'm not yet aware of. I don't know of anything else that would prevent the ECM from not sending the signal either. If anyone knows of other issues that could cause that please let me know. I was able to find the starter relay location (R10) in the engine bay fuse box from the diagrams as well, but its integrated into the PCB somehow. Any advice on the electrical system testing would be appreciated! This should be interesting though. I'll report back with what my multi-meter finds.

 

If PATS is unhappy (e.g. fails to see the key as OK) it flashes a code. Watch the PATS light as you try to start the engine and if it flashes keep watching and counting the flashes for an age till you see the pattern.

If you turn the key and PATS goes out then it's happy.

 

It's not like the old days when the starter would turn no matter what, on modern cars it all runs through the ECU, so if the ECU doesn't get all the expected indicators it won't turn the starter, but if all the wires and earths are still intact, etc, you can, as you did, bridge the starter and it will turn, but the ECU will not be involved in this and so the start, fuel and security systems will still be inactive, meaning it will not start. I had a similar fault on a Rover75 where it just wouldn't go, and that turned out to be loose connections at the ECU. try the old wiggle test with the ECU plugs.
The brake fault could just be the low battery level throwing up codes when the voltage drops below a certain level, the suspension will not raise until the compressor runs, and as long as the gearbox is in park, the car will not move.
If you are just mucking about, then get the battery up to a good charge level, hook it up to a computer/code reader, read all the codes, note them all down and go over every last one to see if there is anything that might be causing a no start, then clear everything, try it again, power down, then read codes again, the main problem is that most fault codes will not show up until the system it relates to is active. but for the time being, your main focus will be on any "P" codes.
The key you have is the only real unknown here, not done it for years, but it used to be possible to change over the security module and keys with a donor car, and that would fix things, but today...?
Of course there is a possibility, it's just a good old fashioned faulty ignition switch, or a gearbox inhibitor switch, try wiggling the gear lever as you turn the key, and wiggle the key as you turn it. been there, done that, and had favorable results.

 

Now it's multiple modules for immo - change them wrongly and car will go into anti-theft.

Don't add more pain!

 

Thanks for all of the responses, I really appreciate it! I think this whole thing was a huge oversight on my part, trying to thing of everything that could be wrong, and getting scatter brained. I should have mentioned that when I got the car the security light blinked once then 5 times, and repeated. I thought the blinking was normal and the battery wasn't that bad since the electronics worked fine. Also I watched videos on jaguars with security faults that showed a rapid blinking light while the dash specifically said security fault. However, when I changed the battery recently and didn't look at the light again after. I was focused on the dash lights. Anyway, the security light blinks rapidly now, and still no security fault warning on the dash. So I didn't even get to break out the multi-meter. I don't know if the battery swap made it lose security or if it as already lost but was just acting weird because of low voltage? Because now the "Vehicle to low warning" is not on (I do have the front wheels on jack stands though, but the rear is really low and still has sensors???). Also the brake fault warning is gone. A new warning is up though, It says "car light is off" ?????? Whatever that means?? I know all the lights are off, Jaguar! Anyway, I checked for engine codes with the cheapest code reader out there, but didn't find any codes. I'm not sure if the computer got reset and all the warnings were lost but are still there waiting to be re-scanned and pop up? Anyway I guess the immobilizer is now apparently the issue regardless, with possible hidden mysteries. The cheapest solution I can find is a bypass unit by Fortin that will work with this model for about $33 USD with shipping. Unless anyone knows a cool trick with a simple paperclip or something, I think ill have to try that out and see what happens since 3rd party repairs are out of the question.

 

Sounds like PATS is not happy so it will refuse to try to start.

An attempt to bypass is unlikely to do anything but add pain.

You will have PATS code(s). Probably others. You can either go back and do things properly (make sure battery is good and charged!) or you may need a tow to a competent tech.

 

Unfortunately the cheapest of code readers is just that, cheap, these normally only cover engine codes, I picked up a Foxwell NT644, so from Machine Mart for £330, which covers pretty much all modules on my X350, It also covers over 50 other makes. They do cheaper ones that cover specific manufacturers. I Have not looked at security module, mainly because I have no problems with it, I can't remember whether it covers it or not, and as the car is under a foot of snow just now, it will be a little while before i can plug it in and have a look. I thought about going for the Jaguar specific model, but as I do work on other cars, I went the extra couple of hundred on that one.

 

Even a cheap $5 one will show things like anti-theft / key not recognised.

 

B-rad, Any updates on your starting issue? I have been wondering if the problem was/is PATS related.

 

Sorry no update yet. I have been working on another car redoing the front suspension. I'll be taking a crack at it again this week, though. From what I can tell it is PATS. The security light is blinking rapidly. I did get ahold of a Fortin bypass but, It's still unclear if I can program the bypass with just one key, when the directions says it needs two for programing, but some cars can just use the same key twice while programing? Also unclear If it will store the immobilizer password so i can just completely go around it with the aftermarket valet key? I also know nothing about the key, It is possible that the key was only cut to get into the car by the insurance company without really doing anything with the PATS chip inside the key? This is a Copart insurance auction car after all. Finally Its also not clear how to wire it for the Jaguar. The instructions aren't that useful.

If I do need two keys to program the fortin unit....I heard that the aftermarket wireless key/keyfob combo can be bought reasonably cheap on ebay and cut by the dealer, then the fob can be wirelessly programed by some sequence. That method can be done with just the one newly cut key from the videos Ive seen online. I might just have to get the key made and it will at least turn the engine? maybe?

The other option would be to get a donor car. I have my eye on a cheap 2003 XJ v6 right now. It doesnt have air ride but I could use some things like the bumper, rims, radiator (maybe), switches, and things. I'm not sure but I read somewhere that it might be possible to swap out the dash cluster (where pats is located), ignition lock cylinder, and the driver door lock, all with the key from the donor car, and it might work? That really seems like the most work, and questionable on how the mileage will read after doing something like that, and who knows what else could go wrong with that?

Is the car just really stubborn? Or is it just me? I wish this issue was talked about more or that there was more info on repairing the issue from home. If anyone has gone through this before though, I'd love to hear the story on how to fix it. Thanks