I'm going to float a question out there for the truly professional Jag mechanics. Rather that chasing around wiring, fuses, bulbs and replacing instrument clusters as have been suggested in past threads (however for earlier year models) I'm going to pose the question before I state the problem:
Who has the Jag OEM shop manuals as to the protocols to enter the programming mode of the center console touch screen control panel.

There is a hidden menu in the touch screen that can be entered into using a secret on-screen key to touch and hold somewhere.

The problem in the XK's and XF's (mine is an '09), is that the message center is just too damn dim to see in daylight, or slightly better at night-- even with the display light dim-bright pop-up knob on the panel turned all-the-way up, and the touchscreen Vehicle Settings > Cont./Bright adjusted to bright:


In the sunlight, the Message Center LED display illegible... like turning your cellphone screen to almost dark. This has got to be a simple setting to increase the system brightness (below is NOT an example of the display brightness, the phone camera adjusts for low light.


HOWEVER, in the diagnostics mode, the true illumination settings are revealed, which makes me believe that there are probably internal factory default settings that can only be reached through the diagnostic touch-screen programming function.



Perhaps there is a factory default setting that could be reprogrammed to provide a higher illumination... just like going into the settings on a cell phone.

As well, the Touch-screen Vehicle control of the Contrast/Brightness... may apply only to the touch screen, whereas the Message Center illumination may only be adjustable from the knob.

Would there be anyone in Jag world would possess keen insight into this conundrum?

 

So your max brightness is turned all the way up? I have 09xf premium luxury and it is bright as all hell during day and at night I have to turn it down. I can't really see a hidden menu option being able to increase brightness beyond what the factory settings are.

 

Also there is a walk through on the fourm that guides you how to get into the exact option your looking for.

 

The "Hidden Menu" is the gateway to programming by Jaguar techs.
Yes, I'm quite sure the illumination level is set to a factory default, and as LED screens age and become dimmer with age, I'm sure the factory defaults can be changed or adjusted.

The "hidden menu" is accessed bu holding something on the screen for 5 seconds. I just don't know what that is, but it's got to be in the service manual somewhere. As you can see, my LCD reads "48". That sounds low to me-- less than half the maximum brightness (assumed to be 100).

 

Depending on the year, there are slight differences as to the access of either the engineered or diagnostic modes utilizing the dash, center or both screens. The options are also slightly different. As such, I would recommend using the SDD software with more control and explanation than the On-Board system. If you feel brave enough to play around with the on-board system with the high chance of unintentional changes to your configuration without recourse and with my final warning as there is a chance of royally screwing things up and then you are on your own, here is the directions from the 2010 manual.

Navigation Diagnostic Screen Access

1. With the vehicle at rest, place the ignition switch in either "ACC", "ON", or start the engine.

2.On the "Menu" screen, press the top center of the screen for more than three seconds.

3. Enter the PIN code and then touch "OK".
660: Diagnosis Menu screen
661: System Check screen (DTC code verification screen)
662: GPS Information screen.

4. The diagnostics screen will be displayed.

Alternative method is to go into navigation, navigation menu, then destination entry. At the top where it says Destination Entry, hold screen right after title print for 5 seconds.

 

Hold the phone; so we can read and clear DTCs without use of a scan tool?

 

If and when you try it and depending on year, it is a general code display you need to reference from the Jaguar dtc list. And no, it just is a display, there is no clearing that I am aware of.