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  • ECU Diagnostics


    How to check the ECU for errors:

    This site has the info for 180sx and CA18DET engines, which is fine for the exa/CA18DE

    Here are some pics for checking on the exa:

    DCP_7296..JPGDCP_7295..JPGDCP_7293..JPG

    The ECU for EXAs sits under the passenger seat, so grab a screwdriver and undo the front 2 screws holding the plastic cover on, and 1 screw on the back of the plastic cover. Next there are two screw on the front of the ECU chassis holding it to the floor of the car, remove them too. Then you need to slip the cover up over the ECU and then slide the ECU forwards a bit and twist it 90 degrees to get it out from under the seat (or just do it how you want , so long as you are carefull and get it out from under there).

    DCP_7287..JPGDCP_7289..JPGDCP_7291..JPG

    Once you have it out, you will be able to see the adjustment screw and the red and green LED's. This is where you grab your printed article from the URL above, and follow the instructions. The main points to follow are (from URL above):

    * Mark the original position of the screw, or just remember where it was.
    * Turn the ignition 'ON' , don't start the engine. - Turn the ECU adjusting screw fully clockwise.
    * The lamps will flash a number of times with a longer break between each string of flashes. E.G. The inspection lamps will flash once, the unit will be in mode I. The inspection lamps will then flash twice, the unit will be in mode II. The inspection lamps will flash 3 times, the unit will be in mode III. The unit will continually cycle through all five modes until the screw is turned back anti clockwise just after the needed mode flashes are done. - Turn the screw back after the lamp has flashed 3 times. - You are now in self diagnostic mode III.
    * 4. Reading the trouble codes.

    The codes are indicated by the number of flashes on both red and green lamps. First the red lamp flashes and then the green one. The red lamp corresponds to units of ten and the green lamp to units of one. For example, when the red lamp flashes once and the green lamp flashes twice, this signifies the number "12". There may be more than one code, there is a long break between each set of red then green flashes to separate them if there is..

    The codes are: Possible cause: Symptoms:

    Code Possible Causes / Solutions Symptoms
    11 - Crank Angle Sensor Wiring fault (connector), CAS is worn or requires cleaning if NG then replace. No or difficult starts, bad idle.
    12 - Mass Air Flow Meter Wiring fault (connector), MAF may need cleaning, if NG then replace. No or difficult start, lack of power.
    13 - Engine Temperature Sensor (or Water Temperature Sensor) Wiring fault (connector). If sensor NG then replace. Engine stalls, lack of power, poor economy.
    14 - Vehicle Speed Sensor Wiring fault (connector). If sensor NG then replace. Lack of power, poor idle.
    21 - Ignition signal missing in primary coil. Wiring fault (the circuit between the power transistor unit and ECU is opened). Power Transistor may be faulty, replace if NG. No or difficult start, bad idle, misfiring.
    31 - E.C.U. (E.C.C.S. control unit faulty) Wiring fault, ECU internals?
    33* - Exhaust Gas O2 Sensor Wiring fault, sensor requires replacement. Lack of power, low economy, possibly running rich.
    34 - Detonation Sensor Wiring fault, detonation sensor itself may be faulty if so replace. (Temporary work-around, at your own risk! - disconnect the plug to the sensor and use a 1mega Ohm resistor to short circuit) There may be other causes for detonation such as boost on a turbo car, poor fuel.. so reset ecu and drive around to ensure that code 34 comes up permanently before replacing it. Lack of power under 3500rpm due to ECU retarding timing to reduce detonation.
    35* - Exhaust Gas Temperature Wiring fault, bad sensor, bad catalytic convertor. Lack of power, low economy, dash lamp.
    43 - Throttle Position Sensor (TPS) Wiring fault, Throttle body may need cleaning?, faulty TPS. Lack of power, low economy, stalling.
    45 - Injector Leak Wiring fault, seal around injector stuffed, injector itself needs replacing. Fuel smell, poor power.
    44 - ECCS normal operation All systems go.
    55 - No malfunction All systems go.

    *unleaded models only.

    There may be some more but I have not finished the list yet. After the diagnostic codes are viewed, turn the ignition 'off' to return to mode I. Then return the screw adjuster to roughly its original position OR half way if you forget where it was. To erase the memory, use mode IV. The codes are automatically erased from memory when the starter is operated fifty times after the last trouble occurred.

    Legal Stuff + Warning: This procedure is pretty safe to do as you do not need to short out any ECU or connector links to get the ecu codes, you only need to turn 1 screw with a screwdriver. However use these instructions at your own peril as usual, if you hurt yourself or the ecu, or the car or anything else the club, it's members and Robert Perkovic cannot be held liable.
    Comments 1 Comment
    1. Carlcamon's Avatar
      I have a huge misfire in my 1988 Nissan pulsar nx se. i replaced all the coils, and spark plugs. i tested the wire connectors to each coil pack and they are reading but when i unplug the 4th coil pack from the engine it does not effect the engine. what is the cause of this?