Does anyone else have a difference in reading between the speedo and cruise display?

My cruise display under reads, but the speedo is correct against GPS. E.g. 50mph on GPS is 50mph on speedo, but cruise thinks it's 53mph

garrycol wrote:

As indicated in the quote, in the later D4 equivalent RRS you can adjust for different size tyres by using something like the IID tool etc.

But what about the earlier RRS? Can it be done with it?

You could send pat an email @ gap diagnostics 👍
I’m sure he can help 

Thanks - I just thought someone on here would know if it is possible.

Cheers

Garry 07MY RRS TDV6
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In the UK if you think you have an error in your speedo then you can easily check it using the verge/ hard shoulder markers on any UK motorway and most major A roads in England.

At the side of the hard shoulder on all UK motorways there are small blue and white position posts used by HA to locate you when you have a breakdown or when they are doing maintenance - these are 100m apart and are on both carriways of all UK motorways and many urban dual carriageways. If counting posts every 100m is too taxing then, in England only, there are blue signs with orange or white text on them every 500m that give the motorway number and the distance to the next junction.............. Both can be used to calibrate your speedo along with a good quality timer, and this is actually more accurate than using a GPS.
As an aside, in the last few weeks there has been a big military exercise going on in UK waters and GPS accuracy has been reduced in many areas because of this, and in some sea areas and coastal districts in the North and West of Scotland GPS has been completely switched off......... it is to stop the Navies of the world cheating in the exercise and forces them to resort to old fashioned eyeball navigation, but the rest of us have to suffer getting lost as a consequence !
https://www.thesun.co.uk/news/6155261/roya...-training/ 2020 Pangea Green 1st Edition D240 New Defender 110 is here and loving it
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that would explain why I ran my kayak aground in the Solent at the weekend (my excuse and I'm sticking to it)! Merc C220 estate Sport AMG
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They can’t just turn off GPS, it doesn’t work like that. They would more likely retain the relevant crypto key from those they don’t want to cheat. Aircraft such as Typhoon and Tornado need valid Crypto to actually work and if it’s not a valid key, the AC won’t fly. 2019 5.0 SC SVA (Current)
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They can and do which is one reason why the EU wants its own system - I’m a day to user commercially and we have received numerous navigation warnings over the last month advising. They only switch it off in set locations, or rather they remove 8 or 12 channels that renders the accuracy so wildly out it is unusable....... USA did the same in the Red Sea a couple of years ago when they were assisting the Saudis with Yemen and further back when they were sending the cruise missiles into Baghdad we had never ending alarms on or ingtegrated bridge systems 24/7 for months when operating in the Middle East. It is one reason why I have GLONASS availability now as well on my ECDIS systems onboard - too many shipboard systems rely on satellite navigation of one nationality or another. China has its own system and India is also developing one for the Indian Coast regions. 2020 Pangea Green 1st Edition D240 New Defender 110 is here and loving it
2018 Melting Silver Mini Countryman PHEV - soon to be replaced
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Also in my garage is a 1996 TDi300 Defender 90 County HT made into a fake CSW

As Tim says, they can - GPS jamming get's advertised when naval exercises are being carried out.

Here is an example - https://www.orcadian.co.uk/orkney-waters-host-military-exercise/ 13MY Range Rover Sport Autobiography SDV6 - mine
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Tim in Scotland wrote:

They only switch it off in set locations, or rather they remove 8 or 12 channels that renders the accuracy so wildly out it is unusable....... .

land rover must have bought a huge batch of sat navs with the channel options permanently removed  

I compared my speedo to several of the 30mph smiley face speed warning signs that flash the speed up and found at 32mph it never triggered them at 33mph it did. Also compared it to the one's that show your speed when approaching them as well and found it spot on, that was after fitting 275/45 x 21" wheels, so figured the speedo was accurate enough not to get a ticket. If you want a more accurate reading you could always try driving through a few fixed speed cameras at a specific speed then when you get the tickets you will know what speed you were actually doing.


Cheers
Col

insiorc wrote:

As Tim says, they can - GPS jamming get's advertised when naval exercises are being carried out.

Here is an example - https://www.orcadian.co.uk/orkney-waters-host-military-exercise/

Stuff that runs in conjunction with it includes mobile phone networks, street lighting, traffic light system timers and a host of embedded bits in equipment that require super accurate timing, that you never thought needed GPS! I have no objection to loss of accuracy provided we are told about it (which mostly professional user are) - after all I was trained and spent a lot of my profession in the time when we had to use a sextant (or Decca Navigation in coastal waters) to find our position and that didn’t always work out error free and someone often switched off the sun by sending clouds over at the critical moment - loss of GPS signals is nothing new, just that it has an effect on far more people than it used to. 2020 Pangea Green 1st Edition D240 New Defender 110 is here and loving it
2018 Melting Silver Mini Countryman PHEV - soon to be replaced
2015MY Corris Grey SDv6 HSE Dynamic, the best car I have ever owned, totally reliable only a cou0le of rattles in 3 years, now no longer in my care
Also in my garage is a 1996 TDi300 Defender 90 County HT made into a fake CSW

garrycol wrote:

garrycol wrote:

As indicated in the quote, in the later D4 equivalent RRS you can adjust for different size tyres by using something like the IID tool etc.

But what about the earlier RRS? Can it be done with it?

Does anyone know?

Cheers

Garry

d-9 wrote:

Does anyone else have a difference in reading between the speedo and cruise display?

My cruise display under reads, but the speedo is correct against GPS. E.g. 50mph on GPS is 50mph on speedo, but cruise thinks it's 53mph