Consult plug showing pins to connect for diagnostics

Used on Nissans from 1989 until around 1998. (Note USA changed much earlier than this) 14 pin grey plastic plug in fuse box area below & to the right of the steering wheel.

• Turn the ignition key to the ON position but do not start. Orange “Check engine” light will illuminate along with oil pressure light etc.
• To access error code retrieval mode use a small piece of wire, e.g. paperclip, to connect the bottom left two pins for approximately 2 seconds.
• Disconnect wire.
• After approximately 2 seconds “Check engine” light will start flashing fault codes. Long flashes are tens, short flashes are ones, e.g. 5 long flashes followed by 5 short flashes is code 55 = normal.
• To check O2 sensor, start engine. Light ON=rich, OFF=lean.
• Check that the check engine light blinks more than 5 times every 10 seconds at 2000 rpm in neutral when warm.

• Take the kick panel off the centre tunnel beside your clutch foot & on the other side. You'll see your computer in the middle.
• Unbolt the computer from the car, there'll be enough cable to get it out the passenger side.
• Take the top off so you can see the 'diagnostic mode selector' trimpot rather than trying to turn it through the access hole.
• Turn the ignition switch on, but do not start the engine.
• Turn the pot fully clockwise. Wait at least 2 seconds, then turn pot fully counter clock-wise. The ECU is now in Diagnostics MODE II
• Read the codes flashing from the check engine light. Long flash is first digit, short flash is 2nd digit, see the codes below.
• To exit MODE II, turn pot fully clock-wise. Wait at least 2 seconds, then turn the potentiometer fully counter clock-wise, or…
• Start engine with the ECU in MODE II to enter MODE II - Heated Oxygen Sensor (O2) Monitor . The ECU is now monitoring the O2 sensor. Warm the engine to normal operating temperature, then run at 2000 rpm for 2 minutes. Check that the check engine light blinks more than 5 times every 10 seconds at 2000 rpm. NOTE: Light indicates signal from sensor to ecu. ON=rich, Off=lean. Blinking light means system is constantly adjusting between lean and rich which is normal. Any other indication would be abnormal and require further investigation. The switched on/off is 'closed loop', while a constant on or off is 'open loop' 11. To exit MODE II - Heated Oxygen Sensor Monitor, turn the potentiometer fully counter clock-wise and stop the engine.

• Take the kick panel off the centre tunnel on the driver's side (This was on a right hand drive model, not sure about left hand drive). The ECU will be visible in the middle. There is a little circular window on the ECU, with a red LED visible inside.
• As in the first method, turn the ignition key but do not start the engine, and using a piece of wire/paper clip, short the bottom left two pins (on the plug located beneath the fuse box), for about 2 seconds, and then remove.
• The LED within the ECU should begin flashing the fault codes.

• 11: crank angle sensor circuit
• 12: air flow meter circuit 13: engine coolant temp. sensor circuit 14: vehicle speed sensor circuit 21: ignition signal circuit
• 26: boost pressure sensor 31: ECU 32: EGR function 33: exhaust gas sensor circuit (left) 34: detonation sensor circuit
• 35: exhaust gas temp. sensor circuit 42: fuel temp. sensor circuit
• 43: throttle position sensor circuit 45: injector leak 51: injector circuit 53: exhaust gas sensor circuit (right) 54: signal circuit from A/T control to ECU
• 55: NO malfunctions in the above Trouble Code: Detected Items: Malfunction Caused By: Check::
• 11* Camshaft Angle Sensor circuit (CAS) Either 1° or 120° signal is not entered for the first few seconds of engine cranking. Either 1° or 120° signal is not input often enough while the engine speed is higher then the specified RPM. Harness and connector (if harness and connector are OK, CAS might be bad)
• 12 Mass Air-Flow Sensor circuit (MAS) The MAS sensor circuit is open or shorted (abnormally high or low voltage is registered). Harness and connector (if harness and connector are OK, MAS might be bad)
• 13 Engine Coolant Temp. Sensor The Engine Coolant Temp. Sensor circuit is open or shorted (abnormally high or low voltage is registered). Harness and connector Engine Coolant Temp. Sensor
• 14 Speed Sensor circuit The Speed Sensor circuit is open or shorted. Harness and connector Speed Sensor switch (reed switch)
• 21* Ignition signal circuit The ignition signal in the primary circuit is not entered during engine cranking or running. Harness and connector Power Transistor Unit
• 26 Boost Pressure sensor (Turbo models) The boost pressure sensor is open or shorted (abnormally high or low voltage is registered). Harness and connector Boost pressure leaks Boost pressure sensor
• 31 ECU ECU calculation function is failing Replace ECU
• 32 EGR function EGR valve does not operate (valve spring does not lift) EGR valve EGRC-solenoid valve
• 33 O2 Sensor (left side) The O2 Sensor is open or shorted (abnormally high or low voltage is registered). Harness and connector O2 sensor Fuel pressure Injectors Intake air leaks
• 34 Detonation Sensor circuit The detonation sensor circuit is open or shorted (abnormally high or low voltage is registered). Harness and connector Detonation sensor
• 35 EGR Temp. Sensor The EGR Temp. Sensor circuit is open or shorted (abnormally high or low voltage is registered). Harness and connector EGR temp. sensor
• 42 Fuel Temp Sensor circuit The Fuel Temp. Sensor circuit is open or shorted (abnormally high or low voltage is registered). Harness and connector Fuel temp. sensor
• 43 Throttle Position Sensor circuit The Throttle Position Sensor circuit is open or shorted (abnormally high or low voltage is registered). Harness and connector Throttle position sensor
• 45 Injector leak Fuel leaks from the injectors Injectors
• 51 Injector circuit The injector circuit is open Harness and connector Injectors
• 53 O2 Sensor (right side) The O2 Sensor is open or shorted (abnormally high or low voltage is registered). Harness and connector O2 sensor Fuel pressure Injectors Intake air leaks
• 54 Signal circuit from the automatic transmission (A/T) (A/T models only)

Used on Nissans from around 1999 on (earlier in USA)

16 pin plug, each side of plug has a taper making the bottom longer than the top.

• Turn ignition key to the ON position & do not start the car.
• Connect bottom left & bottom right pins of plug with a short piece of wire, e.g. paperclip
• Disconnect after about 2 seconds.

This is how you reset the check engine light. No tools required!

In car ECM Diagnostics/ECM Reset procedure:

1) Sit in the driver's seat.

2) Turn the ignition key to the ON position and wait three seconds. (Do not start the car.)

3) Fully depress and release the accelerator pedal five times in less than five seconds.

4) Wait exactly seven seconds. Fully depress the accelerator pedal for ten seconds until the MIL light flashes.

5) Release the accelerator pedal and start counting flashes to obtain the four-digit trouble code.

Long flashes (0.6 seconds) indicate the first digit of the code; count the blinks one through nine and write down the first digit. (Ten blinks indicates a zero.) The next three digits follow in turn in the same fashion except with faster blinks (0.3 second) and a 1.0-second pause between digits.

The ECM code repeats intself until you turn the ignition key to the OFF position, at which point the ECM resets itself to standard get-in-and-drive-the-car mode. You can look up the trouble codes in the ESM/FSM; there's a bunch of them. In the ESM, refer to page EC-639. Additionally, if you get four blinks of ten (0000), the ECM is indicating no malfunction.

You can clear the code (and the annoying MIL) by holding down the accelerator pedal for more than 10 seconds while in Diagnostic Test Mode II. When you release the pedal, the ECM erases the trouble code(s).

• 0000 NO SELF DIAGNOSTIC FAILURE INDICATED
• 0100 MAF SEN/CIRCUIT
• 0110 AIR TEMP SEN/CIRC
• 0115 COOLANT T SEN/CIRC
• 0120 THRTL POS SEN/CIRC
• 0130 FRONT O2 SENSOR
• 0131 FRONT O2 SENSOR
• 0132 FRONT O2 SENSOR
• 0133 FRONT O2 SENSOR
• 0134 FRONT O2 SENSOR
• 0135 FR O2 SE HEATER
• 0137 REAR O2 SENSOR
• 0138 REAR O2 SENSOR
• 0139 REAR O2 SENSOR
• 0140 REAR O2 SENSOR
• 0141 RR O2 SE HEATER
• 0171 FUEL SYS-LEAN/BK1
• 0172 FUEL SYS-RICH/BK1
• 0180 FUEL TEMP SEN/CIRC
• 0300 MULTI CYL MISFIRE
• 0301 CYL 1 MISFIRE
• 0302 CYL 2 MISFIRE
• 0303 CYL 3 MISFIRE
• 0304 CYL 4 MISFIRE
• 0325 KNOCK SEN/CIRC
• 0335 CPS/CIRCUIT (POS)
• 0340 CAM POS SEN/CIRC
• 0400 EGR SYSTEM
• 0403 EGR VOL CON/V CIR
• 0420 TW CATALYST SYS
• 0443 PURG VOLUME CONT
• 0500 VEH SPEED SEN/CIRC
• 0505 IACV/AAC VLV/CIRC
• 0510 CLOSED TP SW/CIRC
• 0605 ECM
• 1111 INT/V TIM V/CIR
• 1131 SWIRL CONT SOL/V
• 1217 ENG OVER TEMP
• 1401 EGR TEMP SEN/CIRC
• 1402 EGR SYSTEM
• 1610-1615 NATS MALFUNCTION
• 1706 P-N POS SW/CIRCUIT