I've suspected mine under reads the temp for a while now and this weekend I'm going to test it against a known good thermometer. 2012 TDV8 Vogue (L322)

The outside temperature sensors are not exactly scientific instruments and are rarely completely accurate . Ok when moving in clear airflow . Not accurate in slow traffic or stop start driving due to heat soak from a hot engine or even hot brakes . Might need a clean if it’s under reading .

Had a quick look at the external temp sensor behind the grill but there's nothing much to see, I think its working fine as it shows a fairly accurate temperature on the dash and in diagnostics.

Thanks for the suggestion all the same though!

I'm waiting on a replacement BCM to try (it bugs me that it's output to the servotronic is not shown in SDD/Autel)

It was posted on Wednesday by tracked 24 but still no sign of it, as is to be expected with RM at this time of year.

The new BCM finally arrived yesterday, I've quickly fitted it this morning on my way out.

Sadly it's not the smoking gun I was hoping it could have been.

Even with the replacement BCM diagnostics still states the output to the servotronic is 0v and 0% PWM even though I know this isn't true as both the original and replacement BCMs read 7v output on the servotronic wires so they do at least do something.

Click image to enlarge

Sorry that last line should have said:

Does anyone know how to measure the speed signal coming in to the BCM? (From the ABS/instrument cluster?)

Just drained off some power steering fluid into a clear tub out of interest...

Looks like there's Black particles in the fluid?

Could it genuinely be a mechanical issue I.e. a hose breaking down causing all my troubles?

Click image to enlarge

Click image to enlarge

Well without much more direction I've ordered a replacement high pressure hose (pump to rack)

I've checked over all the hoses and this is the only one which i could call 'suspect' as it is very rusty and crusty around the crimped on fittings and the 'U' bend part.

According to the WSM it contains 'bullet shaped restrictors/attenuators'

Perhaps one of these is sticking reducing flow? Or it could be this hose that's breaking down internally and restricting flow to the rack?

(Going back to my previous post about the Black bits I've seen in the new fluid I drained out)

Fitted the new genuine high pressure hose from pump to rack and also double triple checked the security, routing and integrity of the feed hose from res to pump.

Absolutely no difference, not any worse not any better.

I still have the faint whining sound when turning the steering wheel, it then increases in volume once the lock is reached and the pump goes into bypass.

I think next I need to get the wheels off, disconnect the track rods and manually check for binding in the hub/strut assemblies.

Perhaps the faint whine is the sound of the pump working against resistance somewhere.

I feel your pain. I wish I could add something and I hope you fix it soon. At least it starts and runs! 2012 Vogue TDV8 in Aintree green

Some things are a real headscratcher Toby, it should work but doesn't (or in my case it works but not as it should)

Running out of options now as to what could be effecting the steering.

I had an elusive issue on one my other (non RR) cars. Took me 2 years but I did eventually get to the bottom of it and fixed it.

Just recalled I had the steering wheel off not long after buying the car. I didn't torque the retaining bolt to spec when putting it back on.

Just been out and removed the wheel, loosened the bolt and torqued to spec.

Still no different but the thought came to my mind so I just had to check.

I could not find one in the 2006 WM but there is a troubleshooting guide in the facelift WM, though I suspect you would have already seen it. I can't imagine that they're much different in principle.

Thanks Toby,

I do indeed have that troubleshooting guide.

Was hoping to manually check for mechanical binding in ball joints, upper strut bearings, track rod ends and steering intermediate shaft today but the weather is poor where I am.

Decided I best wrap some gifts instead