Hi Jonathan, I've checked my blatmail/email and not seen any diagrams from you, but many thanks anyway. I was using a copy of the build manual that I scanned way back nearer the time that I built the car. The electrical schematic doesn't mention the brake switch. It never occurred to me that it would be on the engine harness schematic - and quite frankly still doesn't make sense! The reason that I mentioned the separate fuse is that 2 of my 3 owners handbooks (it was an early sigma after all, so documents were scarce) show that Fuse A = Brake Lights 7.5A and Fuse B = Reverse Light 5A. Thanks all and hopefully out in the car this week Hi Martin, I think you're right. I will get a replacement and add the original to my radiator collection.