I had this problem with the triumph light bar. The connector under the seat also connects to the same fuse as the tach light (not sure the amperage, which is surprising given the number of fuses I bought before I found the problem), so that isn't going to solve your problem. I had a short in the light switch that came with the light bar, and once I removed that, I had no more shorting problems. I'm still draining the battery at low RMP, though, so if anyone has a sollution to that (e.g., boosting alternator output) let me know.
