Self-Diagnostic System Nissan Pick-ups and Pathfinder 1970-1988

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The self-diagnostic system is useful to diagnose malfunctions in major sensors and actuators of the ECCS system. The ECU constantly monitors the function of these sensor and actuator circuits, regardless of ignition key position. If a malfunction occurs, information is stored in the ECU and can be retrieved from the memory by turning on the diagnostic mode selector, located on the side of the ECU. When activated the malfunction is indicated by flashing a red and green LED light emitting diode, also located on the ECU. Since all the self-diagnostic results are stored in the ECU memory, even intermittent malfunctions can be diagnosed.

A malfunctioning parts group is indicated by the number of both the red and green LEDs flashing. First, the red flashes, then the green flashes follow. The red LED refers to the number of the tens digit while the green one refers to the number of the units digit. For example, when the red LED flashes three times and then the green on flashes twice, this means the number 32. In this way, all problems are classified by the code numbers.

Perform self-diagnosis with engine sufficiently warmed up. After a malfunctioning component has been corrected, be sure to erase memory. To erase code memory:

1. Turn ignition switch ON.

2. Turn diagnosis mode selector ON.

3. Wait for 2 seconds.

4. Turn diagnosis mode selector OFF.

5. Wait 2 seconds. Memory erasure has been completed.

The stored memory would be lost if battery terminal is disconnected

See Figures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11

Fig. 1: ECU code table-Z24i engine through 1986

Fig. 2: Diagnostic procedures-Z24i engine through 1986

Fig. 3: Diagnostic procedures-Z24i engine through 1986

Fig. 4: Diagnostic procedures-Z24i engine through 1986

Fig. 5: Diagnostic procedures-Z24i engine through 1986

Fig. 6: ECU code table-VG30i engine through 1986

Fig. 7: Diagnostic procedures-VG30i engine through 1986

Fig. 8: Diagnostic procedures-VG30i engine through 1986

Fig. 9: Diagnostic procedures-VG30i engine through 1986

Fig. 10: Diagnostic procedures-VG30i engine through 1986

Fig. 11: ECU code table-1987-88 Z24i and VG30i engines