Nissan 240SX/Altima 1993-1998 Repair Guide

Reading Codes


See Figure 1

Click image to see an enlarged view

Fig. Fig. 1: The mode adjusting screw (top arrow) and the red LED (bottom arrow) are located on the driver's side of the ECM-Altima shown

  1. Remove the access cover and locate the mode adjusting screw and LED on the ECM.
  3. Turn the ignition switch ON , but do not start the engine. Both the LED and the malfunction indicator lamp on the instrument panel should be illuminated. This is a bulb check.
  5. Start the engine.

Switching modes is not possible while the engine is running.

  1. If the LED or malfunction indicator lamp illuminates, there is a fault in the system.
  3. Turn the mode selector screw fully clockwise. Wait 2 seconds, then turn the screw fully counterclockwise.
  5. The diagnostic trouble codes will now be read from the ECM memory. They will appear as flashes of the malfunction indicator lamp, or the ECM's LED.
  7. After all codes have been read, turn the mode selector screw fully clockwise to erase the codes.

Turn the mode adjusting screw to the fully counterclockwise position whenever the vehicle is in use.

  1. Turn the ignition OFF .

When the ignition switch is turned

OFF during diagnosis, power to the ECM will drop after approximately 5 seconds. The diagnosis will automatically return to Mode 1 at this time.