U. S. Environmental Protection Agency
Office of Mobile Sources


December 14, 1998              
VPCD-98-14         
LDV)     
     

Subject:  On-Board Diagnostic Guidance - Diagnostic Link Connector Location and Accessibility


Regulatory Requirements

This letter serves to address an apparent misunderstanding by several manufacturers over the required 
location of the on-board diagnostic (OBD) data link connector (DLC). The OBD section of the Code of 
Federal Regulations (CFR) (40 CFR 86.094-17(h) and revisions for subsequent model years) states, "The 
emission control diagnostic system shall provide for standardized access and conform with the following 
Society of Automotive Engineering (SAE) standards."  In particular, 86.094-17(h)(4) states,  "The 
connection interface between the OBD system and testequipment and diagnostic tools shall meet the 
functional requirements of SAE J1962 "Diagnostic Connector," (June 1992)."  This SAE standard contains 
the following requirements:

3.   Vehicle Connector Location/Access

3.1  Consistency of Location - The vehicle connector shall be located in the passenger compartment in 
the area bounded by the driver's end of the instrument panel to 300mm beyond the vehicle centerline, 
attached to the instrument panel, and accessible from the driver's seat.  The preferred location is 
between the steering column and the vehicle centerline.  The vehicle connector shall be mounted to 
facilitate mating and unmating.

3.2  Ease of Access - Access to the vehicle connector shall not require a tool for the removal of an 
instrument panel cover, connector cover, or any barriers.  The vehicle connector should be fastened and 
located as to permit a one-handed/blind insertion of the mating test equipment connector. 

3.3  Visibility - The vehicle connector should be out of the occupant's (front and rear seat) normal 
line of sight but easily visible to a "crouched" technician."

Importance of the Connector Location

EPA has recently promulgated a regulation that requires incorporation of OBD checks into Basic and 
Enhanced Inspection/Maintenance (I/M) programs in calendar year 2001.  In anticipation of this requirement,
 some states have opted to voluntarily conduct OBD checks and participate in test programs to evaluate 
 implementation issues.  From these programs, we have learned that several automotive manufacturers have 
 misunderstood the guidelines set forth in SAE J1962 which is likely to cause
confusion in I/M programs. 




Specifically, DLC locations have deviated from the requirements in the following ways: 

     -    DLCs in rear passenger seat locations;
     -    DLCs with cover panels that require special tools or are not clearly           
	      identified as DLC locations;
     -    DLCs that are in an allowable location but not clearly indicated in the           
	      preferred location, such as:
          +  on center consoles and on instrument panels in "the occupant's normal              
		     line of sight";
          +  on the passenger side of vehicles (i.e. passenger side of the vehicle              
		     centerline); 
          +  and/or located behind ashtrays/coin holders and fuse panels.


Future Model Year Guidance and Certification

We are issuing this letter to provide guidance on DLC location for future model year certification.  
We will expect that 2000 model year and later vehicles have DLCs in the preferred location indicated on 
the attached schematic.  Manufacturers should include information on DLC location and accessibility in 
certification documentation for 2000MY and beyond.  Understanding that this letter may be late for some
2000MY vehicles, I recommend discussion with my staff if a manufacturer is using an alternate DLC location.
Manufacturers must include a justification and full details of the alternate DLC location.  Lack of 
compliance with the data link connector requirements, like any OBD requirement, may impact current and 
future model year certification.  

We will conduct an independent determination of compliance with OBD Regulations regarding DLC location.  
Therefore, optional certification to California Air Resources Board (CARB) OBDII regulations or CARB staff
approval of your connector location does not supersede our determination or the guidance provided in this 
letter.


Past Model Year Vehicles

EPA is currently gathering data regarding possible violations by manufacturers with previous model year 
vehicles. A determination on appropriate action regarding these vehicles will be made based on this data.

Questions or concerns with regard to this guidance may be directed to Arvon L. Mitcham at (734) 214-4522. 

Sincerely,



Jane Armstrong, Director
Vehicle Programs and Compliance Division

Attachment