I haven't had much of an opportunity to use my Jaguar over the past few months resulting in a drained battery.

Today I went to use it, the battery wasn't very well charged, but had enough life to start it without any problems.

I noticed selecting gears had a harsh jolt, and driving off it wouldn't change gear, I think it was stuck in 2nd?

I also got the message which says "Gearbox Fault"

I read the fault code and retrieved P1748 which I believe is Pressure Regulator 5.

What exactly is it? Is it electrical or mechanical? Solenoid?
What does this do?
And how much of a job is it to change it?

From what I can gather it lives in the gearbox and going to be a nightmare job.

Thanks in advance.

 

Reset the code, charge the battery fully and see if it comes back. It might just be a low voltage induced glitch.

With a weak battery, the heavy load of the starter motor can drop the system voltage so low that the electronic modules can malfunction.

 

Bad batteries wreck havoc on these cars. Get that issue resolved and your problem may go away. Easier to test battery voltage than changing transmission bits.

 

Thanks for the advice guys.

I charged the battery up over night.
Started it this morning and it had plenty of life.
Cleared the codes.
Selected reverse gear with a harsh jolt, backed out the drive, selected drive (again with a jolt) and drove down the road but would not change gear.

So went into a side road, did a few selections from Reverse to Drive, then turned it off and on again (I find this fixes a lot of problems)
Then pulling away it was changing up gear and all back to normal

So is this a sign that I have a component about to fail or something is on the way out?

I know my battery is about 4 years old and getting tired, so I think I will get that replaced.

Will use it all this week and see how it performs.

Thanks again

 

It was probably just a battery problem. Driving for a week and making sure the battery is charged will be a good test.

 

With low battery it's maybe now relearning settings. Modern cars really hate low batteries.

 

Hello, thought I would add the conclusion to this thread now I know the answer I cant stand threads where there's no conclusion to the problem.

Anyway, regarding the P1748 error code which was causing "Gearbox Fault" message and would not change gear accompanied by a harsh jolt when selecting any gear.

I did try installing a new battery which unfortunately made no difference and checked the oil level which was fine, so I took the car to an independent Jag dealer.

The outcome was my initial suspicion of the Pressure Regulator which is located in the Conductor Plate in the gearbox.

It has now been replaced and everything is back to normal

Thanks for all your pointers.

Lawrence