astra console display

[duffin]

hi, wonder if anyone can help...after replacing my mk.4 astra stereo with a better one, the temp/ time display does not work. am i right in thinking that the third plug on the stereo loom has anything to do with this? and if so, is there an adaptor or any way i can wire the plug so the display works? can do basic electrics, but chasing this lot is a bit much for me! cheers for any assistance.