A few weeks ago having been on a 25 mile run in my 2011 TDV8, I stopped and shut down the engine. On re-starting the "Transmission Fault" icon came on with subsequent loss of winter/off-road modes.

I have GAP tool. These are the fault codes;

TCCM-Transfer Case

P181D-00 (2F) Clutch actuator changeover solenoid - range/performance

P215B-62 (2 Vehicle speed/output shaft speed correlation - Algorithm based failure - signal compare failure

P279D-02 (2F) Four wheel drive range signal circuit - General failure information - general signal failure

I have cleared the fault codes a number of times but P181D and P279D always return.

I have checked the electrical connections at the Transfer Case and the ECU by the brake master cylinder. No corrosion or damaged wires. I have just replaced the battery.

I selected low range which engaged but then couldn't deselect High range. Using GAP tool and running Transfer case clutch calibration routine reselected High Range. It appears therefore that the High/low range solenoid is working.

I have no real idea what to do next. I have the diagnostic codes. The car drives normally and the transmission shifts normally. No erratic changes, no limp mode ......... all normal except no terrain modes.

Has anybody seen this before and managed to fix? I have trawled posts and there are many variations causing "Transmission Fault". The obvious culprit is the battery or alternator. The alternator appears to work fine and the battery is new (AGM 019).

I can only think to run the two Transfer Case Callibration routines? The transmission is shifting fine.

Any guidance / help would be welcome. I live near Aberdeen in Scotland and therefore Dartford Transmissions would be a bit of a trek. RR L322 TDV8 4.4 SE 2019 to present
RR L322 TDV8 4.4 - 2016 to present
Discovery 2 TD5 - 2010 to 2016
Discovery 1 - 2000 to 2010

Just to clarify, what you appear to be calling the High/Low range solenoid is actually a ‘mode selector’ solenoid, which selects whether the shift motor works in either:

1) range change mode

or

2) clutch actuation mode



The range change itself is accomplished by the shift motor (also called the actuator)



For the P181D-00 DTC, Land Rover seem to be saying it could be caused by the mode solenoid or by the shift motor/actuator.

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Hi Phil, what an amazingly detailed response. Thank you so much for taking the time to do this. I have my work cut out doing some testing.
The transmission has done over 180,000 miles with a mega flush at about 120,000 miles. As I say it continues to drive and shift perfectly fine. Is it not odd that it functions normally other than the loss of offroad/winter modes and that if low range is selected, high range cannot be re-selected?

Thanks again for your guidance, it's what this forum is all about! RR L322 TDV8 4.4 SE 2019 to present
RR L322 TDV8 4.4 - 2016 to present
Discovery 2 TD5 - 2010 to 2016
Discovery 1 - 2000 to 2010

Happy New year Phil.

And thanks again for still imparting your fathomless knowledge on this forum.

@RRPhil, good afternoon. Tell me the voltage to the solenoid should be constant 12V. Should I turn off when changing bands?

I have a problem, the transfer case calibration is not going through. Calibration fails during the clutch calibration phase and a loud clicking noise is heard. Get into the high range.
Replaced the transfer case with a known good one. Everything remains the same, error p2789. From memory, earlier, when measuring SDD parameters, there was a constant 12V on the solenoid, everything worked. Now it constantly shows 6.4V. All current resistance and ground fault tests are normal and operational.
I would greatly appreciate any advice or help.