Series 4 decoders like the SDH164k1's will conform to the 10-pin wiring diagram
Function pads for F1 and F2 are located on the SDH164K1 boards on opposite sides by the front headlight. Functions 3 and 4 are located on the 10-pin wire harness, with the Brown wire being the F3 negative and the Yellow wire being the F4 negative. F3 and F4 functions have a common positive connection to the solder point labeled in the middle of the board.
The common LED sizes used are 3 mm and 5 mm.