The message box displays "transmission fault limited gears available and then it selects a lower ratio gear"
After switching off normal service is resumed but if i accelerate whilst in top gear the fault reoccurs.
How do I determine if this is an actual transmission fault or an electrical issue.
The car has only done 55000 miles.
Any suggestions for a garage to look at it and advise.
If it needs a new transmission any suggestions for who would be best to get it from and fit it.
I am in Bolton.

Any advice welcome.

Lack Of Use, maybe the XYZ switch, as shown here.

Edited.

Last edited by JavaBlack on 9th Mar 2023 10:05pm. Edited 1 time in total

Thank you for responding, the fault has only occurred after the vehicle has warmed up.
Regards
Rob

The transmission controller will have stored an error code for whatever is causing the fault. You need to get the codes read and then report back. We can then have a stab at identifying the cause.

Phil

Hi Phil,
Thank you for responding.
Can you recommend anyone in my area (Westhoughton)
I have a Fox reader but little competence.
Regards
Rob

Lack of use can cause one of the valves to stick. I would do a filter and oil change before looking at new gearboxes. The gearbox valveblock is very complex, and wear can cause problems, but at your low mileage i would change the oil As long as you have not been diving through Rufford Ford!

Hi thank you for responding to my request for help. I have done that job on my previous Disco 2 before so I expect it will be a similar task.
Sounds like good advice thank you.
Rob

Yes its basically the same process. Set the oil level at a set temperature, after changing the sump filter assembly. I would clear the fault codes and see how it goes.

Sorry for not responding to Phil on the codes sooner but I have been tied up sorting a non starting problem on my VW LT Motorhome finally with the help of the AA (turned out to be a failed fuel solenoid which I had to order from Auto Doc in Germany).

I have also been reviewing other ideas form the web to get abetter understanding of the transmission and the debate on power flushing, filters and oil types.

I cleared all of the error codes and set out to reproduce the problem. I didn't get the error message on the dash but did experience a jolt on one kickdown.

These are the error codes recorded after todays extended run out about 50 miles

PCM ( power train control) P0196-26 ?* / Intermittent / engine oil temperature sensor circuit - range
/ performance

TCM (transmission control module) P0730-00 / permanent / incorrect gear ratio

IPC (instrument control module) U024887 ?* / / lost communication with remote driver utility module

VIM (vehicle immobiliser control module) B1 B0 * 1-87 / intermittent / key transponder

If this throws any light on the issue please let me know.
Meanwhile if there are any recommendations for some one or garage who could sort this problem that would be useful. I am not back to full physical fitness yet but I am sure I could manage a fluid change.
Would you advise removing the mechatronic valve body unit at the same time ?

The P0730 code indicates that you have clutches slipping/mechanical failure, which is clearly fairly serious. The Land Rover recommended fix for this DTC is ‘renew the transmission’ but your ZF 6HP26X transmission has a well known weak point, caused by wear in a phosphor bronze bush at the rear of the stator shaft. This bush also acts as a seal for the E-clutch hydraulic circuit, so when it wears it allows pressure to escape, causing the E-clutch to slip. The E-clutch is used in 4th, 5th and 6th gears so when the transmission tries to upshift from 3rd to 4th the controller immediately detects clutch slip and drops the transmission back down to 3rd gear, to protect it. Knowing this, might it be possible to establish if your transmission is going into failsafe immediately following a 3-4 upshift?

Phil

Hi Phil,
thank you for your reply.
As far as I can tell the transmission changes gears smoothly and through the full range without any issue.
Obviously with the exception of the two incidents where the message was displayed and the transmission selected a lower gear.
I have used the vehicle locally without any apparent issue and today I took an extended journey involving driving 40 - 50 miles today slowing to 50 in top gear and accelerating to 70 then easing of in each instance the box changed down then back up normally. A mix of motorway and urban driving.
I have been unable to reproduce the problem.

From your explanation it appears that the next step is to source either a reconditioned box or a box repair and and someone to do the work.

I could probably have managed to remove the valve block myself if that had been the problem but anything involving removal of the gear box or transfer box is beyond both my physical capabilities and my equipment hence my request for advice on a suitable establishment.

I do appreciate your help and advice.
Regards Rob

I found this website, might help you. https://go4trans.com/transmission/6hp26/

My bet is life expired seals. I used to life aircraft parts, and seals were always a headache. Certain rubber compounds, over time either go hard, or with certain fluids, go soft, and fail under pressure. The commom rubber compounds have a shelf life of seven years, so under stress might fail at eight years old, for instance. Not a problem where the service interval is one year, but on road vehicles, one expects them to last for ever. I once calculated the expected life of a Triumph motorcycle frame as fiteen years, according to aircraft fatique calculations. The motorcycle was still on the road at sixty years old! five years ago.

Thanks again for your responses, the site is very informative and I will enjoy digesting the info.
From what Phil as said it looks as though the gearbox is toast so I am looking for the right outfit to sort it out for me and the best option to go for.
There is an outfit in Huddersfield which is reasonably near. Do you have any suggestions.?
Regards Rob

HI, Huddersfield Auto Transmissions advertise Landrover gearbox repairs and exchange units. I know nothing about them, but their website makes the right noises.

Thanks for that, reasonably local I think I will drop in and see what they quote. I found Turners who are in Hemel Hempstead not as convenient as Huddersfield.

Not sure what mine is worth and the other option is to sell it.

It is truly immaculate had very light use 56000 miles (spare wheel and tyre unused, rear seats never sat on etc) which makes the gearbox fault very hard to bear.

I wonder if any other forum members have used them?

Regards
Rob