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The transmission has it;s own speed sensor other then the engine having it's own CKPS ( crankshaft position sensor which obtains both the crankshaft angle position and speed ) [snip]
The transmission ECU is a Bosch and the engine UCU is a X
In the early design days of OBD 2 and it's shortfalls this may be one of the things not nailed down as accurate ( just an opinion not based on fact )
The engine CKPS does have it's problems before it completely fails
The transmission speed sensor can be easily read from the transmission ECU connector at pin 2 and 38 while you read the 3 shift solenoids and you might as well read the pressure regulator as this may have a fluid open / close function along with the pressure regulation so things don't slam together
Hi Parker,
As far as the schematics show, the 5HP24 transmission either does not have an input shaft speed sensor, or it is not used in the Jaguar implementation. The only sensor shown on the schematics is for the output shaft speed, which is not the engine speed signal that triggers the P0727 code. And since Tim has verified that the transmission output shaft is not turning, the output shaft sensor signal should be flat.
Your thinking about the pressure control solenoid is valid and its coil can be easily tested for plausible DC resistance at the TCM connector.
To complete your thought about the ECM, if I recall correctly, the X300 unit was made by Lucas/Sagem GEMS.
Water leaking from the gaps in the air conditioning ducts ( foam filler seals degraded ) getting into the transmission ECU connector most notably effecting or corrupting the engine CKPS signal ?.
This could account for a P0727 fault code
Thinking in terms of how the transmission should work , the engine speed by the engine CKPS is needed to determain the upshifting points of 4000 ( 5000 for sport mode )
Downshifting would be different in needing the TPS signal going low if it is available in a failure mode default with a loss of signal or loo low of range too low of a expected voltage
The transmission output speed as it directly relates to wheel speed determains which gear the shift solenoids to sequence into ( they are not directly related ( as MV1 open does not = 1st speed ) and not 1st then 3rd
The P0727 code may be a second problem with the transmission just enough to give a nuscence code and not effect it's function just yet
But the observed problem with his transmission being locked up from maybe the pressure regulator dual function of open / closed shutoff and the pressure regulation
Just thinking out laud without knowing that's factual like my speeling
Last edited by Parker 2; Jun 27, 2020 at 02:22 AM.
Cut a slot in the screw with an angle grinder or Dremel to undo them.
Re transmission fault, start the car, put it in gear and have someone push it from behind or front if it's in reverse. See if it gets gearbox to engage, I had this happen three or four times on my previous x300 although normally just reverse would disappear, think only once it lost both drive and reverse.
Normally, I just opened the front door, push the car with my leg for a few meters and it goes fine.
Thank you for all your replies. Sorry for taking so long to reply.
Having gone through all your suggestions I was no further forward, nothing was coming up as bad. I then had some personal stuff happen that meant I couldn't work on the car.
Long story short, gearbox was replaced and is now working.
Hi everyone.
My X300 4.0 has lost drive, forward and reverse. I pulled away from junction with a bit of gusto and there was a funny sort of slipping belt noise and stopped moving. There are no warning lights on dash, have so far checked that the gear selector actually selects gears, both ends of cable are moving, reverse lights are working. The revs do change when selecting gear but nothing happens when try to drive away. Oil level is OK, oil is clean, no funny smells.
My question is, do I need a new gearbox? I'm OK with replacing it myself, just want to know if it's box or anything electrical.
Thanks
Tim
Hi Tim,
I was doing some research on some of my dad's old cars and stumbled across this thread. He purchased this car new in October 1995 and had lots of lovely memories of it. I would love to know more about its history after it left our ownership and would also able to add missing bits of history.
I can see from this picture that it has several modifications from when we had it.
I was doing some research on some of my dad's old cars and stumbled across this thread. He purchased this car new in October 1995 and had lots of lovely memories of it. I would love to know more about its history after it left our ownership and would also able to add missing bits of history.
I can see from this picture that it has several modifications from when we had it.
Kind regards,
John
Welcome to the forums John,
Your post was automatically locked for moderation. I've resolved the problem and approved it.
The OP xj300spartan has not been on the forum since August 2020. However, if he has "notifications" set to ON he will receive a forum message about your new post in his thread.
