Retrieving Diagnostic Trouble Codes

Turn ignition "OFF". Connect scan tool to Data Link Connector (DLC) located under left side dash panel. See Fig 1 . Turn ignition "ON". An OBD-II scan tool complying with SAE J-1978 has the listed mode functions to choose from:

1. Mode 1: Readiness Test
   
   This mode accesses current emission related data input and output values. In this mode, system status information is also monitored.
2. Mode 2: Freeze Frame Data
   
   This mode gains access to emission-related data value information stored by ECM during the freeze frame portion of self-diagnostic mode during engine operation.
3. Mode 3: Diagnostic Trouble Codes (DTCs)
   
   This mode gains access to emission-related powertrain DTCs stored by ECM. For DTC definitions, see DIAGNOSTIC TROUBLE CODE DEFINITIONS in appropriate SELF-DIAGNOSTICS - SENTRA article in ENGINE PERFORMANCE. For DTC U1000 and U1001: CAN Communication Line, see DIAGNOSTIC TROUBLE CODE DEFINITIONS  .
4. Mode 4: Clearing Codes
   
   This mode can clear all emission related diagnostic information for DTCs. These include:
   • Clear number of DTCs (MODE 1).
   • Clear DTCs (MODE 3).
   • Clear DTC for freeze-frame data (MODE 1).
   • Clear freeze-frame data (MODE 2).
   • Reset status of system monitoring test (MODE 1).
   • Clear on-board monitoring results (MODE 6 and 7).
5. Mode 6: On-Board Tests
   
   This mode accesses the results of on-board diagnostic monitoring tests of specific components and systems that are not continuously monitored.
6. Mode 7: On-Board Tests
   
   This mode enables the on-board test drive to obtain test results for emission-related powertrain components and systems that are continuously monitored during normal driving conditions.
7. Mode 8: EVAP System Testing
   
   This mode can close EVAP system with ignition "ON" (engine "OFF"). The listed components can be opened or closed:
   • EVAP canister vent control valve can be opened.
   • Vacuum cut valve by-pass valve can be closed.
   During the listed conditions, mode 8 cannot function:
   • Low ambient temperature or low fuel temperature.
   • Low battery voltage.
   • Engine running or ignition switch in "OFF" position.
   • Too much pressure applied to EVAP system.
8. Mode 9: Calibration ID
   
   This mode enables external test equipment to request specific vehicle information such as VIN and calibration IDs.

For further information, see appropriate operation manual supplied by scan tool manufacturer.

Fig 1: Locating Data Link Connector

Courtesy of NISSAN MOTOR CO., U.S.A.