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Put the battery on a minder. Np troubles since but I have been watching the voltage. Is there a threshold where the system will power the rest of the car (like the roof) but not the starter
Put the battery on a minder. Np troubles since but I have been watching the voltage. Is there a threshold where the system will power the rest of the car (like the roof) but not the starter
Not really, but usually window memory loss and/or ABS faults are first indications of a failing battery.
I'm having a no start (no crank) problem so am trying to learn about the security system in case that is why it does not crank.
What was the final solution to this problem, please?
And if security system does not like key because transponder chip or other circuitry is bad, does dash message area not wake up or does it simply not crank or cranks but won't start because there is no gas or spark?
Thanks,
John
So all indications point to the KTM, the key itself, or maybe the exciter coil. I checked continuity on that and got some 27-30 ohm so it may be ok, but I'll swap it with a known good piece from another car and see for sure. Seems like that's a problem area....
***ALL IN THE NAME OF SECURITY****
Hi all... I'm in a very similar situation here... I have power to both hot spots on my starter relay (I need to check the relay control pin for grounding at key turn)... My question is about the exciter... IF the exciter DOES recognize the key,,, is it's signal to the KTM generic OR does it send a specific programmed signal to the KTM? If it is a matter of exciter recognizing key,,, generic message to KTM,,, KTM sends a specific message to BPM, SCLM and ECU and all,,, well shoot - I have an exciter, matching key and barrel I can swap into my flood rescue car, for now...
XJsc,,,, when you say "I checked continuity on "that" and got some 27-30 ohm" ----- what do you mean when you say "that"? Which component? And, is there a sure fire test for the exciter or the KTM?
Also, I've been looking over the electrical guide (ain't my strong point) and I cannot find the "rotory switch" mentioned... What and where?
Thank you guys so much,,,,
This is making me crazy, lol
Last edited by JayJagJay; Dec 13, 2019 at 08:22 AM.
If you REALLY want to know, there is a paper out there. The whole scheme was reverse-engineered by some academics a few years back. It was in a VW context, but the tech is the same. It made some noise back then, with the courts being involved.
The idea is to have the chip/transponder in the key "compute" a number resulting from the scrambling of an input number provided by the ECU and a secret key downloaded in the chip during pairing with the car. That same secret key is also known by the ECU so the ECU can compute that same scrambling. If the 2 separate scamblings match, then the key was paired to the car and the security check passes. The exact implementation is a bit more complex, but it is the idea. My sense is that the ECU controls everything, and sends messages to the KTM to activate the coil and transmit or receive data from the transponder. The coil is just an antenna that can power and read/write the key transponder. The KTM works the coil. The ECU "talks" to the KTM and has all the smarts.
To my knowledge, there are Jaguar/proprietary messages when this validation fails. Maybe you can wrap the key head in foil to make this fail on purpose and see if it does anything different. Are you even sure this key works? Pairing to the car needs to be done on all keys you have (including valet) because a new secret needs to be downloaded. All keys not updated stop working.
So the exciter is passive, only amplifies, and sends the keys code to the transponder...?
The transponder is also passive, and sends that info to the BPM to give the green light...? Or does the transponder give the green light? From this,,, it looks like the transponder sends the message to fuel and the security acknowledgement to the BCM which sends it elsewhere...?
If that is the case COULD a matching key, exciter (maybe the exciter isn't so important here) and importantly the KTM from a donor give the green light to the BCM which will then send the signal to other components...?
If I put foil on the end of the key and push it into the barrel, I'm afraid it will get stuck in the barrel... That wouldn't be good...
Looks like fueling and security green light happens in the transponder?
If you REALLY want to know, there is a paper out there. The whole scheme was reverse-engineered by some academics a few years back. It was in a VW context, but the tech is the same. It made some noise back then, with the courts being involved.
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Fmertz, appreciate the reference to this, often wondered about this.
The value of the immo setup is approximately a large negative number to me since my playtoys are inexpensive compared with the latest kia sedan, the parts are not particularly valuable unless you get them from the dealer (and they certainly would not accept them back from my stolen car...), and, if driven, would stand out like a 'please arrest me' sore thumb around here owing to their comparative rarity..
The XK8 appears to have a Megamos 13 from 97 to 99, then a Megamos crypto 48 from 2000 to 2006. The crypto is the chip that is the subject of the hack as noted by fmertz. Building the multiple terabyte tables necessary is now child's play and the computational requirements appear to be accessible to the crappiest laptops around.
The legality of defeating the encryption on your own car is probably certain in the US (it's likely okay, but I''m not an attorney and do not play one on TV either, so this does not constitute legal advice, just ill-informed opinion under the First Amendment to the US Constitution, no deposit, no return, shake well before using, contents may have settled...). Unclear outside the US.
Has anyone found out what causes this? My 1998 xk8 has had a no crank/no start for months now. My original problem was the alternator was bad swapped it out and it said that alternator was bad. My mechanic the unhooked the battery to the car while running to see if the car would run off the alternator and it die. Before i turned the key to off the battery was hooked back up and the car started 2 more times. Then when you insert the key and turn it to the on position, all lights carry checks come on there's no codes and no security light on when turning the key to crank you hear a click in the dash that sounds like it's coming from the bpm area. If you jump the starter relay the engine will turn but never fire. I have sent the car to the dealer to see if pairing the key to the car will work and it did not they where able to pair the key to the car but it still would not start. I sent the ecm to a specialist and there's nothing wrong with it at all. I have a brand new battery in the vehicle. Any advice would help!
Maybe this excerpt from Electrical Guide might help
Drdude21,
Sorry to hear about your long standing starting troubles. Maybe this figure from the Electrical Guide might help you track down your fault.
You seem have done a lot of things. But I have a few thoughts - have you checked the inertia kill switch in the fuse box at the dash/door? Do you get a spark when trying to start? Plus fuel delivery - fuses, relays, pump primes, pressure at the fuel rail?
DavidYau,
I have checked the inertia switch it's perfect I've checked my grounds my relays my fuses and I've checked my fuel pump, my spark, and fuel delivery and everything has checked out perfectly I will take a look at this diagram and see what else I can look for
If the key is NOT recognized, you will get a P1260 DTC in the ECM.
bob
When this happened to me, I checked for ECM codes using my DTC scanner and did not see any recorded. My car had been parked for a couple of weeks in the driveway outside while I was on a trip. There were no issues with the battery, i.e. battery OK. When I returned, it would not crank or start. I had it towed to a shop and all that was done was to reprogram the key. We had some storms while I was gone, and I always was suspicious that perhaps a lightning strike had occurred nearby and somehow upset the ECM. Lightning strikes happen sometimes in my neighborhood, but I had no evidence that one had actually occurred.
Any update on these other no crank cases that cars were sitting?
My 98 sat while I ordered timing chains and got time to do it. Got it back together and the battery was a brick.
New battery and it wouldn't crank. Immobilizer communication faults in BPM and ECM. Engine spins over beautifully if I jump the starter relay.
I have power and ground at the KTM, and continuity to both ECM and BPM, which both have power and ground. Neutral safety switch is in the correct position, and input confirmed using the JLR diag software.
It seems like a dead KTM.
Does anyone know if I can install a used KTM and get the keys programmed to it?
Our local dealer does not work on cars this old.
Last edited by Offroader1006; Apr 15, 2021 at 03:09 PM.
