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Jaguar XK8 turns and won't start - no spark - Solved... kinda

XK8 / XKR ( X100 ) 1996 - 2006

Jaguar XK8 turns and won't start - no spark - Solved... kinda

 
  #41  
Old 02-02-2019, 05:20 PM
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The Body Control Module is behind the glovebox.

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  #42  
Old 02-02-2019, 08:47 PM
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I didn't see where the battery capacity was tested, but if it has not been load tested, I would do it. A fully charged battery should read 15.6 volts. Use a load tester with a 1000 amp capacity. If it's just a little low, the low voltage circuits in the ECU will get below threshold and not work. Keep in mind that some of the voltages in the ECU circuits run below 6 volts. If the battery is low, low voltage circuits will drop exponentially.
 
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  #43  
Old 02-03-2019, 04:25 AM
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Personally I think you have spotted what is wrong already. I think its where you insert the key. Give it a good spray of electrical or MAF cleaner. Id guess the key system still thinks the key is out and therefore the system is still disabled.
 
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Old 02-03-2019, 08:05 AM
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The first thing I tried was to put a brand new and fully charged battery in. No change. The car starts up fine as soon as it gets a bit wormer inside a garage.

The current theory about the key being the issue (transponder, or just the barrel) is hopefully the right one. I did try before giving the car to the dealership to warm up the ignition lock and everything around it to no effect, so my guess will be with the transponder in which I didn’t look into initially because I was told the car doesn’t have one...
 
  #45  
Old 02-03-2019, 08:28 AM
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It is my understanding that the gate for the key has nothing to do with starting the car. What it may do is not allow the car to go to sleep and in my experience cause the tone that the key is still in the cylinder.
 
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  #46  
Old 02-03-2019, 11:20 AM
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Originally Posted by oldmots View Post
I didn't see where the battery capacity was tested, but if it has not been load tested, I would do it. A fully charged battery should read 15.6 volts.
Typo for 12.6V?

And I'd say at least 12.6V (as it could be a bit higher than 12.6V), though you'll get away with a little less most of the time.
 
  #47  
Old 02-03-2019, 12:05 PM
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Exciter ring/KTM or not can be determined by looking at the key. If you have them, there will be an insert in the key as shown here in this post by DevonDavid:
https://www.jaguarforums.com/forum/x...7/#post1682276
edit: apparently not necessarily true if the car was originally from NA as some keys may still not have the transponder even if they look similar to the one in David's link. KTM is tucked behind fascia fusebox.

IMO if the car cranks, then the security system is not the issue.
 

Last edited by michaelh; 02-03-2019 at 12:40 PM. Reason: correction
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  #48  
Old 02-03-2019, 12:36 PM
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Originally Posted by michaelh View Post
Exciter ring/KTM or not can be determined by looking at the key. If you have them, there will be an insert in the key as shown here in this post by DevonDavid:
https://www.jaguarforums.com/forum/x...7/#post1682276

IMO if the car cranks, then the security system is not the issue.
Both keys are with the dealer. I only have the ones from my UK donor car and will check them later tonight. It doesn't make sense to me too for the car to crank but not to deliver spark and fuel... But at the same time if the mechanic is right, if the car does not have a KTM, then the "security" check is done using the starter motor. If I understood correctly, once the starter motor starts turning, it sends a signal through a ground wire to the body module, which then gives an all OK for starting the car. Or something like that. He didn't have much time to check into this, but has only measured the starter motor and got on that wire once 9V and once 0V. In both case the car won't start.

As always the temperature thing is killing me... what will be working above 10C and not when under It is neither too cold or hot for a cold solder to be the issue, or for a ground wire not to have good contact with a nut somewhere. Super weird...
 
  #49  
Old 02-03-2019, 01:02 PM
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I do feel for you:- intermittents can be a royal PITA.

My gut feel would tend towards the ECM (particularly as it's a 97) or the inputs it receives from the cam & crank sensors- but you say you have tried substitutions with the same result?
I guess it's possible thermal expansion might case an intermittent connection. Catching this while it is in fault mode is the only way forward unless you are able to substitute everything implicated.

I disagree with the tech's assertion about the starter motor. There are no outputs from it other than the torque to the starter pinion.

Note I've corrected my earlier post (should have read more deeply), although that only applies to early NA cars, AFAICS.
 
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  #50  
Old 02-03-2019, 01:30 PM
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Yes, I tried substituting the ECM, and the crankshaft sensor. I told the mechanic to try and change the camshaft sensor too. I have a whole working UK car (well... was working before I took the engine out ) as a donor, so in a worst case scenario I can change everything as it is almost an identical match aside from the wrongly placed steering wheel
 
  #51  
Old 02-03-2019, 01:39 PM
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The KTM is mounted above the fuse box and not easy to access.

Originally Posted by michaelh View Post
Exciter ring/KTM or not can be determined by looking at the key. If you have them, there will be an insert in the key as shown here in this post by DevonDavid:
https://www.jaguarforums.com/forum/x...7/#post1682276
edit: apparently not necessarily true if the car was originally from NA as some keys may still not have the transponder even if they look similar to the one in David's link. KTM is tucked behind fascia fusebox.

IMO if the car cranks, then the security system is not the issue.
 
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  #52  
Old 02-04-2019, 02:10 PM
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Hey, I've had a similar problem, now sorted.
ignition coil relay, LHS in engine bay was loose.
(2001 XK8).
Hth.
 
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  #53  
Old 02-04-2019, 02:15 PM
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Thank you, but in my case the ignition coil relay is just a symptom of another issue.

Tomorrow I am going to take the KTM from the donor car and give it to the mechanic. It is actually not that hard to get to, and as the instrument cluster is coming off, it would be a perfect opportunity to replace its bulbs

Am I correct to assume that it is enough to replace the KTM and the mechanical key barrel, so that the key from the donor car be recognised in my car? Do I need to replace the transponder ring, too? Is the BCM needed too?
 
  #54  
Old 02-04-2019, 04:38 PM
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The KTM reads the key that is in the cylinder that it is programmed for. So if you take the KTM from another car the key you have for the car you are installing it for will not be correct. In order to fix the problem you will need to reprogram the KTM with the key for that car. The exciter ring only reads the key chip.

Also along with removing the instrument cluster you will need to remove the vent cover. Once that is done you will need to remove 2 mounting screws for the KTM. The one in front is easy access but the one in the back is not so easy to get to.

 

Last edited by Gus; 02-04-2019 at 04:42 PM.
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  #55  
Old 02-04-2019, 11:34 PM
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I do have the keys from the other car and was planing to use them instead of reprograming my keys. I already have the lock barrel from the donor car disassembled. I was just wondering if the key’s key is stored anywhere else as in more modern cars, but I guess not
 
  #56  
Old 02-05-2019, 12:27 PM
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Might work.

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  #57  
Old 02-05-2019, 12:29 PM
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I hope so! I did shed some blood removing the KTM an hour ago I do not believe it is meant to be removed without removing the dashboard, too... Will share pictures later tonight
 
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Old 02-05-2019, 02:11 PM
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Hi kainy,
I knew I'd seen this somewhere but couldn't remember. It's from the "SERVICE TRAINING COURSE 682 ADVANCED JAGUAR ELECTRICAL SYSTEMS"
I'm sure it's available from Gus' site: JagRepair.com - Jaguar Repair Information Resource

It explains the sequence of events for starting the car:

"
Passive Arming: Vehicles with Key Transponder Module (KTM)
Engine cranking and starting are controlled by the ignition switch, ECM, BPM, P / N signal, key transponder module,
ignition key reader exciter in the ignition switch, ignition key transponder and the gear selector not-in-park switch.

Cranking and starting are accomplished in the following manner:

Ignition key switched from the OFF position
• KTM receives a signal from the ignition switch position I as the key is turned
• KTM energizes the reader / exciter, which causes the key transponder to broadcast its security code
• If the key transponder code matches the programmed KTM code, the KTM outputs an OK TO START signal to
the ECM via a serial data link
• ECM receives OK TO START signal and transmission P / N signal (hard wired from transmission), and enables
fueling and ignition
• ECM outputs a SECURITY ACKNOWLEDGE signal to the BPM via a serial data link
• BPM receives a park signal from the gear selector not-in-park switch and enables cranking if the security system has been disarmed

Ignition switch to position III (CRANK)
• Ignition position III crank signal is received by the BPM
• BPM grounds starter relay coil to energized starter motor
• ECM receives starter relay coil signal and sets engine starting values

"
I'm afraid it pretty much rules out the KTM
 
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  #59  
Old 02-05-2019, 05:03 PM
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Like I said before, I do find it weird it cranks but does not give fuel and spark. Still after what I went through to get the KTM out of the donor car I told the mechanic to first try heating it up before disassembling anything.

But he did told me that today he tried again the spare ECM. To be honest I have never tried it when the car was able to start. But the last couple of days it was pretty warm so naturally the car was working. However, with the donor ECM the car wouldn’t start. It will try, will put fuel and spark, but would cut off irregularly. So tomorrow the mechanic will try to register the ECM to the car and see if it will start. He still hopes it might be the ECM. I did remove the BPM too, just in case, so that he has everything


And now about the KTM. That peace of s**t is a pain in the a** to remove The guide I had found through my documents wasn’t very helpful



everything is fine until “remove driver side duct”. I couldn’t find a guide how to do this. I did find it had only 1 screw on its back, just behind the KTM. Have in mind that I am 6f7” getting under the dash and putting my hands inside it is practically impossible... so the duct cannot get out and it is blocking 1 screw of the KTM. The big wiring loom is in the way. It can probably budge if the two nuts seen on the pic are unbolted, where the screws are on the other side. With a lot of swearing one of them can be unscrewed, but the other one has a steel pipe in front of it (this dashboard has waaaay to much iron in it ). May be removing the whole steering column may help, but it was already 9pm, 4C temp and the car is in the middle of a muddy yard with no lighting... so I butchered the duct

 

Last edited by kainy; 02-05-2019 at 05:05 PM.
  #60  
Old 02-05-2019, 06:30 PM
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As before - I feel your pain!
You are at least fortunate that you have some spare parts to hand.

Do I understand correctly that when it's cold enough for the fault to be present, swopping the ECM makes no difference? if so, it likely excludes it as a suspect, especially if the donor module was fine in the other vehicle.

The fact that the car cranks means that the ECM is happy that all is good on the security front. I wonder if it's seeing the 'crank the motor' signal that the BPM generates? This fires the starter motor relay so we know it's getting out somewhere and could be what your tech was referring to. If it can't, then it's not going to tell the coils & injectors to do their jobs:- it won't know the motor is turning.

Another possibility is the ECM isn't receiving the signal from the crank position sensor so doesn't know when to fire the coils or injectors. I believe you've tried swopping this:- are the wiring & connectors definitely OK? As per Gus' note, you need to confirm that the signals are getting to the ECM - checking at the sensor end doesn't do that.

Are there no codes thrown at all? Even a cheap ELM327 and Torque should be able to give you any Pnnnn codes.

I hope my KTM never goes bad...
 
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