Page 27>28 in the RACETIME2 manual.
The direct connection to the DB15
Ground = 10 <> Pin 5 DB 9
Data transmit = 14 <> Pin 2 DB 9
Data receive = 15 <> Pin 3 DB 9
Pin 10 will also be used for the impulse ground so you need to take care jumping another cable onto the ground pin. Use shrink tubing to isolate it.
Connection to the 6 pin DIN Plug that connects to Serial I/O (display) output on the connection box.
Pin 1 = Data Transmit <> Pin 2 DB9
Pin 5 = Ground <> Pin 5 DB9
Pin 6 = Data Receive <> Pin 3 DB9 (not really needed for TOD transmit to PC)