Instrument lighting relay

[Inky]

Hello everyone - new here, so sorry in advance for any rookie mistakes!

I did take a quick look around the forum but couldn't find what I needed; if someone has already covered this a nudge in the right direction would be good :)

I have an lighting fault - driving along at night and the instrument lighting will go off, and the cluster brightness will jump to day time levels (digital dash). It seems like a relay fault to me - but it can't be a fault in the main high load relay because the headlights don't fail, just the instrument lighting. I'm not sure whether there is a secondary relay, and if so where to find it - or whether all the functions are on the one main headlight relay unit which I couldn't locate anyway (wasn't where the wiring diagram said - must be differen on the Aussie models. That or I'm blind).

Any advise would be appreciated, particularly just in regards to where the relays are hidden!