OTC Genisys OBD-I DB-25 to DIN-8 cable

Stuart Schmitt, 10 October 2021

This is the OTC 3305-72 cable used to connect OTC Genisys, Mac Mentor, and Matco Determinator scan tools to OBD-I vehicles. The pinout/wiring diagram is below.

Image of DIN-8 and DB-25 connectors with pin numbers

DIN-8 DB-25 Function
— 25 Power
1 12 Signal—ECM receive (SCI)
2 14 Relay control (ASD)
3 15 Signal—differential bus negative (CCD)
4 13 Signal—ECM transmit (SCI)
5 16 Signal—differential bus positive (CCD)
6 23 Chassis ground
7 11 Signal—unknown
8 10 Signal—possibly pulldown resistance for adapter identification

Notes

  1. The DIN-8 pin numbering follows IEC 60130-9, not the incorrect numbering commonly found in OTC documentation.
  2. Chrysler applications (SCI, CCD, ASD) are noted in a useful thread on turbododge.com.
  3. The DIN-8 connector and DB-25 connector plus hood are available at Mouser Electronics.
  4. The DIN-8 connector and DB-25 connector plus hood are available at Digi-Key Electronics.