As an ex mechanic, the problem is a simple one. Like most of you I originally wired my spotlights via a 4 point relay with the switching wire to the main beam wire of the headlamp connector with the same results as most of you.
O.K. The answer This is a simple solution really. Firstly wire up your relay as per the instructions ( make sure the wire carrying the in line fuse holder is of a sufficient amperage for the current 30 amp wire should do it )then run the switching wire( the one you are told in the relay instructions to connect to the main beam on your headlamps ) through the bulkhead on the nearside, where under the dash, bolted onto the side of the car you will find the headlamp dim dip relay. This is a black oblong box some 3"X 4" in size with 2 rows of terminal connectors going to it. It does actually say dim dip relay on it ( it does on my 4 track anyway ) Here you need a voltmeter, and with the ignition turned on set the voltmeter to 12 volts d.c.Run the negative line from the volt meter to earth and with the other wire check the current fluctuation as each terminal as the headlamps are switched to dip and main beam. The wire on my 1994 4 track is red with a white tracer and is slightly thicker than the other wires. I simply scotchlocked my switching wire to that and I now have spotlights on with my main beam. In all it took me about 1 hour to do it.