E30 Zone

There is a lead that goes through the bulkhead in front of the passenger's feet then along the left side of the engine bay. One wire goes to the air temp sensor which plugs into the left-hand air tunnel that leads from the air intake in the spoiler. The other wire goes to the horn (sounds if immobilser is tripped). The horn is covered by a largish plastic cover. I need to know the location of the OBC horn, does anyone have a picture?

It should be a steel cover, not plastic, and the horn locates immediately below the ABS pump, but underneath the panel.