You can retrieve the trouble codes from your '94 Nissan pickup right from your home garage, saving yourself both time and money. 1994 Nissan pickups come equipped with an on-board diagnostics I computer (OBD I) that retrieves and stores all trouble codes sent to it from various sensors within the pickup. When these sensors detect a problem in the Nissan, they send the code to the computer. The computer illuminates service and warning lights on the instrument cluster. You can retrieve these codes using a handheld device called an OBD I code reader. This can be purchased online or at any auto parts retailer.
Locate the diagnostic port near the steering column on the underside of the driver's side dashboard. It will be the same size and shape as the connector on the OBD I code reader.
Plug the code reader into this diagnostic port.
Put the key into the ignition and turn it to the "II" position, taking care not to start the engine.
Wait for the code reader to turn on. Select the "Read Codes" command (or a similar command) on the face of the reader. Wait for the code reader to display the codes. Write down the codes it displays.
Look up the meaning of the alphanumeric codes in the manual. Unplug the reader and perform the servicing or repairs the vehicle needs based on the information obtained from the codes.
