Common issue with 20 year old hot hatches.... So many alarms fitted by "Stevie Wonder" over so many years it one of those things you find...
Only car I've ever seen without a butchered loom was a GL I had last year.... every single part of the loom had been untouched since it left the factory inc the stereo...
but no good for a GTI as it didn't have the MFA loom..
Sold it to a guy in Japan, who was doing a rebuild...