A common issue for car owners is the inability to connect a Data Link Connector Scan Tool, often referred to as an OBD2 scanner. This article explores a specific case involving a 2001 Nissan Altima GLE with 199,800 miles, experiencing connectivity problems with various scan tools. The vehicle owner has attempted multiple scanners without success, indicating a potential power or communication issue at the OBD2 port.
The first step in diagnosing this issue was to eliminate simple solutions. The cigarette lighter fuse, often linked to the OBD2 port’s power supply, was replaced despite the lighter functioning correctly. Thorough inspection and cleaning of the OBD2 connector with electrical contact cleaner were also performed, but the problem persisted.
The owner confirmed possession of a multimeter, a crucial tool for testing electrical circuits. This allows for checking the presence of voltage at the OBD2 connector pins. Specifically, pin 16 should have battery voltage (around 12V), and pin 4 should provide a ground connection. Using the multimeter, one can determine if power and ground are correctly supplied to the port. Pin 2 is for J1850 Bus+ communication and Pin 10 is for J1850 Bus-. Pin 6 is for CAN High (J-2284), Pin 14 is for CAN Low(J-2284). Since there is no communication the J1850 and CAN lines should be tested.
Beyond the immediate connectivity issue, the vehicle exhibits symptoms suggesting underlying engine problems. The engine runs intermittently on 4-6 cylinders, accompanied by a flashing Check Engine Light (CEL). The owner, through individual cylinder coil driver disconnections, suspects the misfire originates in the rear cylinders, potentially requiring intake manifold removal for access. The intermittent nature of the misfire, sometimes clearing under heavy acceleration, adds complexity to the diagnosis. A functioning data link connector scan tool would be crucial for retrieving diagnostic trouble codes (DTCs) stored in the vehicle’s computer, providing valuable insights into the root cause of the misfire and the communication failure.
In conclusion, resolving the data link connector scan tool connection issue is paramount for diagnosing the broader engine problems. Verifying power and ground at the OBD2 connector with a multimeter is the next logical step. This case highlights the importance of a functional scan tool in modern vehicle diagnostics, enabling accurate identification and resolution of complex issues like intermittent misfires and persistent CEL activation.
