The Data Link Connector (DLC) is the diagnostic interface port used to communicate with Honda Engine Control Units (ECUs). Depending on the vehicle's model year and On-Board Diagnostics (OBD) generation, Honda utilizes either a proprietary legacy 3-pin connector or the standardized SAE 16-pin J1962 connector.

Proprietary 3-Pin Data Link Connector (OBD0 / OBD1)#

On OBD0 and OBD1 vehicles (roughly 1988–1995), Honda used a proprietary 3-pin DLC port to transmit serial K-Line diagnostic data.

• 2-Wire vs. 3-Wire Configuration: Depending on the specific model and trim, this connector may be populated with either two or three wires:
  • 3-Wire Models: Provide a constant +12V power supply line, Ground, and a Serial Data line. This allows diagnostic scanners (such as the dealer-level Vetronix Mastertech) to power up directly from the port.
  • 2-Wire Models: Only contain the Ground and Serial Data lines. When using a diagnostic tool on these models, the scanner must be plugged into an external 12V power source (such as the cigarette lighter socket or battery clips).
• Service Check Connector (SCS): The 3-pin DLC is always located directly adjacent to a separate 2-pin blue connector. This is the Service Check Connector (SCS) or Service Check Signal port, which is shorted with a jumper or paperclip to read flashing CEL codes on the dashboard.

3-Pin Connector Locations#

• Right Lower Edge of Passenger Dash:
  • 1994–1995 Accord (L4)
  • 1992–1995 Civic
  • 1993–1995 Civic del Sol
• Behind Front of Center Console:
  • 1992–1995 Honda Prelude (Note: Typically a 2-wire setup requiring external tool power).
• Behind Passenger Glove Box:
  • 1995 Honda Odyssey
• Left Driver Kick Panel:
  • 1994–1995.5 Honda Passport

3-Pin DLC Hardware Views#

Proprietary 3-pin blue DLC connector (right) and 2-pin blue SCS connector (left) on a 1992–1995 Civic.

Close-up of the integrated diagnostic port bracket.

Standardized 16-Pin Data Link Connector (OBD2)#

Starting with the V6 Accord in 1995, and standard on all USDM vehicles by 1996, Honda adopted the standardized 16-pin OBD2 DLC (SAE J1962).

• Communication Protocol: Honda uses the ISO 9141-2 protocol for OBD2 communications. Pins 7 (K-Line) and 15 (L-Line) are utilized for communication.
• Pin Configuration: Out of the 16 pins, Honda populates up to 7 pins for standard emissions diagnostics. The remaining pins are used for proprietary Honda systems (ABS, SRS, etc.).

16-Pin OBD2 DLC Locations#

Because OBD2 standardized the connector but not its exact cockpit placement, Honda utilized several locations depending on chassis architecture:

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Location Guide by Model#

• Under Driver Side Dashboard (Pointing Down):
  • 1998–2002 Accord
  • 1996–2000 Civic
  • 1996–1997 Passport
• Behind Center Console Ashtray:
  • 1995–1997 Accord V6
  • 1996–1997 Accord L4
• Behind Center Console Access Cover:
  • 1996–1997 Odyssey
• Behind Front Center Console Trim:
  • 1996–1997 Civic del Sol
  • 1997–2001 CR-V
• Behind Center Console Removable Accent Panel:
  • 1997–2001 Prelude