I've got an alarm fitted, which was probably considered quite sophisticated in its day. It's armed by means of a key switch in the door and sets off an alarm consisting of two horns in the engine compartment, if somebody breaks in and opens any of the doors or hatches. It also goes off if you remove the radio, and immobilises the starter. It's a bit temperamental and I've considered pulling it all out, but since I don't understand it I'm likely to cause more problems. Most of the problems so far seem to be due to bad earths. My preference would be to keep it and use it if it was reliable. At the heart of it is a Bosch Alarmrelais 0335 411 033. I've done a drawing with all the 15 terminals and wire colours, but that's as far as I got. It's a bit crowded under the dash. It went into a number of German vehicles in the 80's, but I can't find a circuit diagram for this. Has anybody got anything on this?