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Home >> Nissan-Datsun >> 1988 >> Sentra Sedan L4-1597cc 1.6L SOHC (E16i) >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Testing and Inspection >> Initial Inspection and Diagnostic Overview >> Description of On-Board Diagnostics >> Diagnostic Test Modes >> Mode Description

Mode Description


The self-diagnostic system is used to diagnose malfunctions in major sensors and actuators of the ECCS system. There are five modes in the self-diagnostic system:
1. Mode I (Mixture ratio feedback control monitor A): During a closed loop condition, the green inspection lamp turns On when lean condition is present and goes Off when a rich condition is present. During an open loop condition, the green inspection lamp stays Off.
2. Mode II (Mixture ratio feedback control monitor B): During a closed loop condition, the red inspection lamp turns On and Off simultaneously with the green inspection lamp when mixture ratio is controlled within a predetermined value. During an open loop condition, the red inspection lamp stays Off. The green inspection lamp function is the same as Mode I.
3. Mode III (Self-diagnosis): The ECU constantly monitors the funtion of various sensors and actuators. When a malfunction occurs, a fault code is stored in the ECU. Mode III allows the display of fault codes which have been stored in memory.
4. Mode IV (Switches ON/OFF diagnosis): During this mode, the inspection lamps monitor switch ON/OFF condition of the throttle valve switch, starter switch and vehicle speed sensor.
5. Mode V (Real time diagnosis): If a malfunction is present during a driving test, the inspection lamps will display the malfunction condition immediately.



Fig. 47 Typical ECCS control unit:





SWITCHING MODES

1. Place ignition switch in On position.
2. On all models exc. Pathfinder, Pickup and Van, proceed as follows:
a. Turn diagnostic mode selector on ECU fully clockwise and wait until inspection lamps flash, Fig. 47. Number of flashes displayed indicates corresponding Mode.
b. Note number of flashes, then immediately turn diagnostic mode selector fully counterclockwise.
3. On Pathfinder, Pickup & Van, proceed as follows:
a. Turn diagnostic mode selector on ECU to the ON position and wait until inspection lamps flash.
b. Note number of flashes, then immediately turn diagnostic mode selector to the OFF position.
4. On all models, when ignition switch is turned Off during diagnosis, in each Mode, and then turned back on again after power to the ECU has dropped off completely, diagnosis will automatically return to Mode I.
5. Stored memory will be erased if battery terminal is disconnected or after selecting Mode III or Mode IV. If diagnostic mode selector is kept turned fully clockwise, it will continue to change the Mode in sequential order and memory will not be erased.


Fig. 159 Modes I & II display indications.:




Fig. 160 Modes I & II display indications.:





MODES I & II

In these Modes, the control unit monitors Air/Fuel ratio and Air/Fuel ratio feedback coefficient. Refer to charts, Figs. 159 and 160, for display indications.



MODE III

The ECU constantly monitors the function of various sensors and actuators, regardless of ignition key position. If a malfunction is present, it is stored in the ECU and can be retrieved from memory by turning on diagnostic mode selector, located on the side of the ECU. When activated, the malfunction is indicated by a series of flashing red and green light emitting diodes, also located on the ECU. When displaying malfunction codes, the code number can be determined by counting the number of light pulses. The red light represents the first digit of the code, while the green light represents the second digit of the code. For example, a Code 12 would be displayed as one flash of the red light, followed by two flashes of the green light. Malfunction codes can be translated using the following decoding chart:
1. Code 11 -- Crank angle sensor circuit malfunction.
2. Code 12 -- Air flow meter circuit malfunction.
3. Code 13 -- 200SX w/VG30E engine, Pathfinder & Pickup w/VG30i engine, Maxima & 300ZX. Cylinder head temperature sensor circuit malfunction.
4. Code 13 -- 200SX w/CA20E engine, Pathfinder & Pickup w/Z24i engine, Pulsar, Sentra, Stanza, Stanza Wagon & Van. Water temperature sensor circuit malfunction.
5. Code 14 -- Vehicle speed sensor circuit malfunction.
6. Code 15 -- Pulsar & Sentra w/E16i Engine. Mixture ratio feedback system slips out.
7. Code 21 -- Ignition signal missing in primary coil.
8. Code 22 -- Maxima, Stanza, Stanza Wagon, 200SX & 300ZX. Fuel pump circuit malfunction.
9. Code 23 -- Maxima, Pulsar, Sentra, Stanza, Stanza Wagon, 200SX & 300ZX. Idle switch circuit malfunction.
10. Code 24 -- 200SX w/CA20E Engine, Stanza & Stanza Wagon. Full switch circuit malfunction.
11. Code 25 -- Pulsar & Sentra w/E16i Engine. Idle speed control slips out.
12. Code 31 -- ECU (E.C.C.S control unit) malfunction.
13. Code 32 -- Pathfinder, Pickup, Stanza, Van & 300ZX Calif. models & Pulsar Calif. models w/CA18DE Engine. EGR malfunction.
14. Code 33 -- Exhaust gas sensor circuit malfunction.
15. Code 34 -- Pulsar w/CA18DE Engine & 300ZX Turbo. Detonation sensor circuit malfunction.
16. Code 35 -- Pathfinder, Pickup, Stanza, Van & 300ZX Calif. models & Pulsar Calif. models w/CA18DE Engine. Exhaust gas temperature circuit malfunction.
17. Code 41 -- 200SX w/CA20E Engine, Stanza & Stanza Wagon. Air temperature sensor circuit malfunction.
18. Code 42 -- 200SX w/VG30E Engine, Maxima & 300ZX. Fuel temperature sensor circuit malfunction.
19. Code 43 -- Pathfinder, Pickup, Pulsar, Sentra, Van & 300ZX. Throttle sensor circuit malfunction.
20. Code 45 -- Pathfinder, Pickup, Stanza, Van & 300ZX Calif. models & Pulsar Calif. models w/CA18DE Engine. Injector leak.
21. Code 51 -- Pathfinder, Pickup & Van. Injector circuit malfunction.
22. Code 55 -- All monitored systems satisfactory.
The diagnostic code retained in the ECU will automatically be erased after starter is operated for 50 times.

MODE IV

In the switches ON/OFF diagnosis system mode on 1987 200SX w/VG30E engine, Maxima and 300ZX, ON/OFF operation of the throttle valve switch, starter switch and vehicle speed sensor can be detected continuously.
In the switches ON/OFF diagnosis system mode on 1987 200SX w/CA20E engine, 1987---88 Pulsar, Sentra, Stanza, Stanza Wagon, Pathfinder, Pickup, Van and 1988 Maxima, 200SX and 300ZX, ON/OFF operation of the idle switch, starter switch and vehicle speed sensor can be detected continuously.
The throttle valve and starter switch on 1987 200SX w/VG30E engine, Maxima and 300ZX or idle and starter switch on 1987 200SX w/CA20E engine, 1987---88 Pulsar, Sentra, Stanza, Stanza Wagon, Pathfinder, Pickup, Van and 1988 Maxima, 200SX and 300ZX, ON/OFF position at the point when Mode IV is selected is stored in the ECU memory. When either switch is turned from On to Off or Off to On position, the red light on ECU alternately comes on and goes off each time switching is detected.
The vehicle speed sensor ON/OFF position at the point when Mode IV is selected is stored in the ECU memory. When vehicle speed is 12 m.p.h. or slower, the green light on ECU is off. When vehicle speed exceed 12 m.p.h., the green light on the ECU comes on.

Mode V

In this Mode, if crank angle sensor, ignition signal, air flow meter output signal or fuel pump (1987-88 Maxima, Stanza, Stanza Wagon, 200SX & 300ZX) are judged to be defective, a malfunction is indicated immediately.



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