Just had my 2011 4.4 TDV8 fail the MOT as the DSC switch on the HEVAC panel didn't work. I've changed the panel for a brand new one off ebay and it still doesn't work!
I've tried diagnosing it with my carsoft and it flags up a DSC Buttton Fault (permanent) , but if I clear it, it comes back. Has anyone any clues as to what it might be???

Ironically the system works fine and there are no warning lights on, but its a MOT fail if you can't switch the system off. Why you would want to ?

The switch gets its power from fuse 35 in the passenger compartment.

Switching DSC off can sometimes be useful in off-road situations.

Is there a warning light or message displayed? It works with ABS so perhaps an ABS system fault is showing and the reason for the MOT fail.

Thanks Graeme, what is baffling is there are no warning lights on at all and the DSC syatem seems to work, not that I have tested it in action!

For the annual MOT test, the DSC system, if fitted, must work and the system switch must be serviceable, ie capable of switching it on and off. My system seems to work, the switch doesn't! I've changed the switch panel (£750+ VAT list) thankfully a lot less on ebay and it still doesnt work. Any ideas anyone?

Can you just explain to the tester that DSC is always on every time the ignition is switched on and will switch back automatically on if CC is enabled while the switch is off?

Have you checked the fuse?

i didn't even know what the switch did until it was pointed out. Ironically it works fine, but the Government website states " (d) ESC switch damaged or not functioning correctly Major" . A major fault is a fail.

I have tried to point out that it does work, only you can't switch it off as required.

I'm going to disconnect the battery later and then see if an old fashioned reboot does anything.

Just had it fixed. A broken wire between the switch and the abs module. Wire replaced and parralled the original, far too complicated to dig out the loom and find the break. All fixed and mot passed.