Been having a heap of electrical problems recently so bear with me. 1998 UK spec terzo

Just got the car about a month ago, it had an aftermarket stereo that kept overheating and switching itself off, narrowed that down to either a bad wire or bad speaker to the drivers door. Disconnected the one speaker and the stereo runs fine on the other 3.

While I had the stereo out I noticed that the aftermarket gauges had a wire run off the stereo harness which made the illumination and battery power come on, I thought it was a live and moved it to the cigarette lighter live, but it was a ground and blew the fuse. Replaced the fuse, and grounded this wire to the chassis directly, and now have working gauges and radio. The radio is wired using an aftermarket harness, all seems to match up and the problem happens even when I removed the radio

The problem is all of my external lights (Front and back) and cluster lights are really dim (couldnt drive at night)and the bright switch on the dash does nothing. Fog lights not coming on at all, but the switch is lighting up. Reading that it could be the illumination control module, bought one, but I cant locate one in any of the three places that they seem to be (behind glove box, behind radio, near steering column)

The only wiring diagram I can find for 1997-1998 is the sti which shows no illuminatuon control unit so now not sure its even there.ELECTRICAL HELP PLEASE😞 Been having a heap of electrical problems recently so bear with me. 1998 UK spec terzo Just got the car about a month ago, it had an aftermarket stereo that kept overheating and switching itself off, narrowed that down to either a bad wire or bad speaker to the drivers door. Disconnected the one speaker and the stereo runs fine on the other 3. While I had the stereo out I noticed that the aftermarket gauges had a wire run off the brown wire in the stereo harness which made the illumination and battery power come on, I thought it was a live (too used to house wiring) and moved it to the cigarette lighter live, but it was a ground and blew the fuse. Replaced the fuse, and grounded this wire to the chassis directly, and now have working gauges and radio. The radio is wired using an aftermarket harness, all seems to match up and the problem happens even when I removed the radio The problem is all of my external lights (Front and back) and cluster lights are really dim (couldnt drive at night)and the bright switch on the dash does nothing. Fog lights not coming on at all, but the switch is lighting up. Reading that it could be the illumination control module, bought one, but I cant locate one in any of the three places that they seem to be (behind glove box, behind radio, near steering column) The only wiring diagram I can fund for 1997-1998 is the sti and where it shows the clusters they are different so not even sure if its the same, with mines being a uk2000 Im running out of things to check and starting to lose the will with it. I've checked all fuses and tried swapping relays around. Also don't know if this is related or not but today ive noticed none of my electric windows are working, but im pretty sure they have done since the issues began🙈 i did swap the relays around in the car under the fuse box


Any help much appreciated as im rapidly losing the plot🤦‍♂️

 

Check al the earth straps / ground wires.

 

Id also give every fuse a check again, have you tested at the lights and fog light for 12v or what voltage you actually have?
Whats the Battery voltage with engine on and off?