In 1994, the Nissan Maxima was still using the OBD-I (On Board Diagnostics version one) computer programming. This system featured on-board diagnostic capability with five manually accessed diagnostic modes. By entering diagnostics manually and selecting mode number three, trouble codes related to component or system faults stored in the on-board computer memory could be retrieved. The codes could then be used to identify code-specific diagnostic routines. The Nissan enthusiast can read access codes in a few minutes and be well on his way to diagnosing performance and driveability problems.
Remove the trim panels in front of the center console. Locate the engine computer attached to a floor-mounted bracket on the transmission tunnel between the console and the firewall.
Turn the diagnostic mode selector, located in a round opening on the side of the engine computer, until it stops. Observe the small red and green LED lights on the side of the computer next to the mode selector. They will flash to indicate the modes, with a pause between each mode. One quick flash is mode one, two quick flashes is mode two and so on. When the light flashes indicate mode three, quickly turn the mode selector counterclockwise until it stops. You have entered mode three diagnostics.
Observe the red and green LED lights on the side of the computer. The red light flashes to indicate the "Tens" digit of the code and the green light flashes to indicate the "Ones" digit of the code. For example, if the red light flashes two times and the green light flashes seven times, this would indicate code 27.
Turn the ignition key off for two minutes to exit diagnostics. The computer will automatically return to mode one for normal operation.
