Unsolvable engine stalling/no cranking/immobiliser problem - in depth description
 

Hey, folks. It`s me again and now I just would like to go in depth detail with my Jaguar X300 3.2 European model problem. I would like to warn the readers, that this will be an in depth description to my problem and following steps i`ve taken to solve it (unsuccessfully) an there will be a plenty of text, so be warned and read carefully. Thanks in advance.

So, my car sometimes stalls when driving and sometimes, when I shut the engine off and then trying to start the car, nothing happens. Now, in detail.

The car ALWAYS starts when left overnight, with first try. Ignition on, all the lights go off in my dash, CHECK ENGINE stays, and the car starts. When i`m driving it for a bit, shutting off the engine and then trying to start it (for example, stopping for gas), often I have no crank. Ignition on, all the lights in the dash go off, and CHECK ENGINE also goes off. Then I just can`t start the car, I can flick the key million times, nothing happens, no crank. When I wait for some 30minutes or something and try it again, mostly I got the CHECK ENGINE light illumintated before the crank, turning the key, car starts and cranks. So - CHECK ENGINE light stays on, i`m always getting the crank and go. No CHECK ENGINE light - no crank. And i`m finding it strange, that the car always starts when left after night, just always. Thats the first problem.
The second one is that sometimes car shuts down when driving it. It just shuts down at pure random. Sometimes under acceleration, sometimes when im rolling with revs to idle. Often, when it shuts down in the middle of the road, it`s difficult to start it again. Sometimes it just cranks and there`s no movement on the tachometer (suspect Crankshaft sensor), sometimes its the same thing as described above. Check engine light goes off and I can flick the igniton all day, no crank.
What I`ve noticed, that sometimes the car sputters and drops the revs when driving, and the Check Engine light is flickering, while the engine is still on. When I slam the accelerator, mostly the light goes off and the car is going again normally.

What i`ve done to solve the problem:
first, I plugged my OBD2 Delphi reader and got the code "P1621", 'P1621 is ECM immobiliser circuit malfunction-out of range voltage for diagnostic line.
I checked the ECU connectors, security module connectors, and the connectors behind the right front headlamp, next to the window washer tank, the connectors are in good condition, no corrosion, i`ve sprayed them with the contact cleaner just to be sure.
I`ve replaced the body processor module with a checked and working one. No changes, just the same thing.
I`ve cleared the car battery ground strap, cleaned it where it connects to the car, i`ve cleaned the firewall bulkhead ground strap (next to the wacuum booster on LHD car), i`ve cleared the engine ground strap under the car. Nothing.
I`ve replaced my crankshaft sensor with a brand new from Britishparts.co.uk in hope to resolve "crank but no start" problem. Nothing changed, it`s all just the same.

Guys, i`m really desperate now. The car is driving me mad, I just don`t know what to do next. It seems to get worse, when I just bought the car it stalled maybe once in a day but now, after 4-5 months its almost undriveable, I just don`t know what to do.
As far as I know, the Check Engine light before crank signalizes that the car is mobile and, when the Check Engine light goes off before start it means that the car is immobilised? What to do in this situation?

Big thanks in advance, I know that this forum is very helpful and trust me, before writing this topic, I`ve browsed this forum a lot in search of answers.
Reinis

Where did you find the meaning of P1621 for your specific (1995 X300 3.) car?

Also, what voltage do you measure
(a) at the battery, when cranking
(b) at the starter motor, when trying to crank (sadly this may be awkward to measure)

How new is the battery and is it definitely the correct kind for the car?

If it happens mostly when engine is hot, it can be your Crankshaft Position Sensor (CKPS), Purge Valve or the ECU, in that order. Mine happened to be the ECU which was corroded at the connectors and hence compromised. Others may chime in.

Certainly worth taking the PCM out and checking its pins / the mating connector and if the PCM can readily be opened having a look inside. Older PCMs can be wet or have capacitor(s) dying.

The sputtering while driving might indicate a fuel problem - which could be a relay, pump, or partly blocked filter. The relay should be easy to swap.

I don't know how many relays & pumps this model has but later ones have more than one - check with care :)

Post #25 https://www.jaguarforums.com/forum/x...ge2/#post45734
may apply.

I'd also suspect the ignition circuitry starting at the switch you put the key in. A loose wire/dodgy connection might really confuse things.

(I guess you'd have to take the steering column apart but see the workshop manual.)

I`ve inspected the ECU, the connectors are in splendid condition, looking like brand new. Haven`t opened it up, though. As i`ve heard, there`s some wiring connectors behind the splash guard in the front right hand wheelarch, will try to look there.
As i`ve described, the crankshaft position sensor is brand new and the problem still persists. It was pretty cheap, though - maybe its a crappy chinese alternative to original that i`ve bought?

by PCM you mean ECU? If so, i`ve already checked it`s connectors and pins. Looking like brand new.

PCM is its standard name. Jaguar are gradually becoming standard :)

Looking at it in how the engine gets it's electrical power for regulation other then a sensor gone bad . The ignition key switch provides a ground through pin # 5 that commands the king relays to close enabling power to the sensors and such .

Just by removing the lower half of the steering column cover you can see the connector and the ignition switch sticking on the key barrel . Mine had some corrosion on this # 5 pin . Check also that that pin # 5 has a good car frame ground as the ground terminal is close by .

You can also swap the king relay on the RH engine fuse box with the one on the LH as it may be intermittent and failing when warmed up .

The ECU controlled relay provides the 2nd source of power for many engine sensors and such and you can swap this relay with the Fog light relay .

All of this you can do youself for free . What an amazing deal .
https://cimg0.ibsrv.net/gimg/www.jag...c03c2f02f9.jpg
https://cimg2.ibsrv.net/gimg/www.jag...601ee091e9.png




Editing with Pics

Hi, Lady P.
Yes, i`ve tried to swap horn and ignition relays, no good, unfortunately. Will try the fog relay/ecu relay swap.
Do you have some additional thoughts about the check engine light and immobilisation problem? Is there any way to disable/override the factory immobiliser?

The immobilizer signal to the ECU is a digital signal from what I understand so it would be difficult to inject one to be able to override . This is not on US models . It may be a nuisance code in your case anyway or could be real . There is the large BT4 connector above the fuel tank that the SLCU and ECU communicate through that may have come loose , but is a pain to reconnect and don't try too hard and bust the hold over locking pin . Mine came with a tywrap to hold the locking bar from migrating loose

The fuel inhibit from the inertia switch can be overridden . You can jumper the 2 white wires with a paper clip as the switch has a history of being intermittent .

While you have the ignition switch in hand you can verify the contacts are good as they sometimes go bad . A quick test would be to rotate the key and wiggle the key to verify the switch stays closed through pins 5 to 1 , 2 , and 3 . Pin 1 and 2 enable the king relays to close and should be close to 0 resistance . The pin 3 is starter rotation enable . Pin 5 to 4 is the key in and out command to the SLCU for the car shutdown / go to sleep mode not related to engine regulation ( ? )

The ECU controlled relay enables power to go back into the ECU as the 2nd independent and separate power source . As you can see it provides power to the fuel injectors . Yours being a European model you may not have the EGR valve and not the second fuel pump for the SC engine , otherwise the print is the same

There is the phenomena of cheap replacement fuses limiting the current into a system without blowing causing problems . Covering fuse # x , Y , and Z

Have you inspected the Papa indy 1 connector pin 4 ( White / Pink wire ) as this is where your 1st power to the ECU goes through from that RH engine fuse box king relay

https://cimg3.ibsrv.net/gimg/www.jag...292a4daa93.jpg



https://cimg9.ibsrv.net/gimg/www.jag...46751c6a9b.png

I think that you may have more than one fault given the no crank when hot condition and the engine stopping when running. The fact that the check engine light goes out and engine won't even crank when hot are significant. You wrote that you have already changed the body processor model but did not mention the security and locking control module (SLCM), which I think is responsible for "reading" the ignition key and sending the signal to the engine ECU to disable the immobiliser software and allow fuel injection. The SLCM also plays a part in turning off the check engine light because this signal is controlled by the engine ECU. You may have a problem with the SLCM or the transponder in the steering column that "reads" the key and sends the signal to the SLCM

There is also an interlock that stops the engine being cranked in drive or reverse. I have heard of the micro-switch in the J-gate failing and the symptom is a fail to crank condition. It is possible that this switch is failing when it gets warm after the cabin has warmed up or with heat from the transmission. When the interlock fails, I don't know whether it affects the check engine light with just the ignition on before cranking is attempted. Maybe someone else who has had this specific problem can advise,

The Microswitch in a gear lever is in operating condition, that I know, because it clicks, if I wiggle the gear lever a little bit out of the P position. Ok, what shoud I do about the security and locking control module? Are there some repair kits or DIY, or I just need to buy complete set with security module and key from another, working car? Is there a possible way to override and just get rid of it? I really don`t need the original immobiliser, so I could live without it, if the override or amputation is possible.

Lady Penelope, thanks for another in depth description, i`ll get to that in the next week when i`ll have a bit of free evenings to tinker with the car. For now I removed the ECU and will open it to see if there`s any corrosion inside. But I highly doubt it, since the connectors are like brand new. Super shiny and clean.

Do you experience intermittent no starter rotation or no light off .
During no rotations are you missing the red " P " light .
If you remove the plastic chrome surround on the shift lever be careful for it is brittle and breaks .
There is a solenoid in the area of the shift lever that will give you a click .

Editing / had a pic somewherehttps://cimg7.ibsrv.net/gimg/www.jag...c0c193bbf6.png

Party solved the problem.

I`ve opened up the ECU for a search of some corrosion, but the ECU was in sterile condition. Like brand new.
Then I`ve swapped Engine Management System Control relay with my fog light relay (nr. 5 and nr. 1 in Lady Penelope`s pic) and i`m driving my trashcan flawlessly for some 3 days or so.
If it stays like that - Lady Penelope, I will mary you.:icon_bowrofl:

I'm a dude , M'Lady P is my car and she has a boyfriend , me , :icon_couchhide:

If you listen to the video you can hear her beautiful British voice .

I know but who cares, you fixed my car. :icon_crackup: :icon_mrgreen:

Anyway, really - thanks. Been driving it around every day now, runs flawless!
Just need to order a couple of new relays to replace old ones.