ZFHP6 Not going above 3rd gear in Drive - ok in Sports mode

I'm working on a 2005 Range Rover Vogue 4.2 petrol supercharged at the moment and have an issue we cannot get to the bottom of. It has the ZFHP6 automatic transmission.

When driving in Drive, at higher speeds a error message 'Transmission Fault' comes up on the dash and the gearbox will not go above 3rd gear.

If you turn the engine off and restart, it resets it until it happens again.

If you put it into the Sports / Manual mode, you can drive normally selecting all gears for hours with no trouble at all, it is only when it Drive mode that the problem occurs.

Error code P0783 3-4 Shift is logged on the ECU as a current error.

We've done a transmission fluid & filter change with no impact, but I don't believe it's related to the operation of the gearbox itself as it is working fine in manual mode.

I've read that there are potentially other issues on the car that can prevent the automatic box going above 3rd gear, such as wheel speed mismatches, voltage issues, steering angle sensor etc.

If anyone has any experience of the same issue or a list of the things that have nothing directly to do with the gearbox that can prevent it going above 3rd gear in auto mode I'd be very keen to hear.

thank you
Ash

Bad batteries are always a thrower of faults, then dodgey connections. Best place to start.

I can only find this which is not really good. This is from my 2011 files so may not be applicable to your box.

J

Thanks J. The battery is not holding its charge, though the alternator seems to kick out 14.4v pretty steadily.
Sounds like a decent thing to try next, thank you. I'm sure we have a few decent batteries around that aren't being used.

The solution of 'replacing transmission' that the PDF suggested seems a bit defeatist!!
cheers

ash1303 said:

The solution of 'replacing transmission' that the PDF suggested seems a bit defeatist!!

Click to expand...

I would agree. but JLR are mostly "fitters" now not mechanics. Plus, the choice of some major components was not the best at some times.

Good luck with it. Let us know how you get on.

J

I would remove the Mechatronic unit and check the E-clutch feed port with air pressure to determine if the rear stator bush is worn & leaking. It’s also an opportunity to check the bridge seal & the 4 rubber jump tubes.

https://www.landyzone.co.uk/land-rover/help-please-gearbox-issue.330768/#post-4269229

Phil