I have a 2011 supercharged with 114,000 miles. Occasionally when I start it up and either go into reverse or drive the car will give me a 3 errors: Gearbox fault, HDC not available, And adaptive dynamics fault.
The car will drive in limp mode...if I shift back to park, I cannot
Reshift the is locked.
If I turn the car off, I can reshift, and the error is not
Always reproducible. I find that if I let the car warm up, and the Rpms Combe down, and shift quickly, the error rarely occurs.
When the car drive, it shifts fine, never has an error...only when choosing from reverse or
Drive.
The code I get is: p0850
Attached are pics

Range Rover dealer wants 9500 to replace the transmission. To me I’ve alway thought this was an issue with a switch, based on the way it reacts...

Batteries have been replaced, and car has correct voltages and battery is charging properly

I don’t want to drop almost 10 thousand USD to fix this...
I know rrphil has retired, but anyone know
If he takes side consulting jobs?? If I can get someone to help me get this fixed, I’ll generously donate!!

Any advice?

I think it is acting like a neutral sensor switch, but may be mechatronic unit, but the tranny shifts perfectly as
Long as initially it doesn’t get the fault code, and if it does it’s easy to reset but turning the car off and reshifting.

Wish I could find a good range transmission shop here in the Us (there is a shop in California the has a lot of experience wit these).

In in the Atlanta area, and everyone wants to replace the whole
Transmission

Maybe the gearbox shift cable is out of adjustment. Can the fault be triggered by moving the shift lever backwards or forwards a little?

No..it requires a full shift

There should also be fault codes stored for the adaptive dynamics and HDC faults. If your tool can't find them then you may need access to a LR-specific diagnostic tool.
Is the first fault message always the same fault? That might provide a clue to the fault as the others are likely only due to the primary one.

Specific fault codes stored are:


P0915-01 and P1706-9a


I think HDC and adaptive dynamics auto when the gearbox faults...

Seems like a switch issue, wire
Issue, or mechatronic issue

If it’s a shifter issue then do a bit of Lubrication on the shifter Bowden cable.

It’s the same gearbox as on the 3.6, which suffered from a sticky cable....

Worth a try and costs nothing.... There is nothing that can't be fixed with a hammer😜😜
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Did you get this solved? Did you end up replacing the transmission? I have the same fault issue happening intermittently.

I have the following codes.

P0716-21
Turbine/Input Shaft Speed Sensor Circuit
Range/Performance - Signal Amplitude < Minimum

P0850-8F
Park/Neutral Switch Input Circuit - Erratic

P0700-02
Transmission Control System (Mil Request): General Signal Failure

The Turbine/Input shaft speed sensor and the Park/Neutral switch are mounted on the same plastic component which is a separate part of the electronic module of the Mechatronic unit. The six connections I’ve labelled A to F in the photo are for the -ve, L1, L2, L3 & L4 and +ve connections for the Park/Neutral switch. F & G are the +ve & speed data terminals for the speed sensor. The positive feed F is shared by the two. I suspect this is where your fault lies.

Thanks for the tip Phil. I am due for a transmission filter and fluid swap so I will pull the valve body and mechatronics unit while I am in there.

How do I remove the plastic housing to get at Pin F?

I see you have a 2011 5.0 SC, so you have the 6HP28X transmission. The connection between the position switch/speed sensor assembly and the rest of the electronic module does not involve any wires. All the circuits between the ECU and the sensors are on metal bars which are spot welded together.

Click image to enlarge