INTRODUCTIONOnly a screw driver is required to read the trouble codes stored in the ECU (Electronic Control Unit). The following instructions allow you to easily read and erase the Self-diagnostic Malfunction Code on your beloved's ECU.Reading the codes requires accessing the ECU and placing the unit in one of two self diagnostic modes using a small flat head screw driver. The codes are displayed by a single RED L.E.D. in the ECU and the Check Engine Light.

1. Accessing to the ECU

The ECU is located at the right of the right side footwell. The "side" is determined as you sit in the car facing forward. (For cars in North America, the right side would be the passenger side)

You need to remove 2- "rivet" type fasteners of the right doorstep in order to get the kick panel out. To remove the plastic fasteners, unscrew the center part and pull out the other part. 2- metal screws and another "rivet" type fastener hold the kick panel.

Under the panel, is the ECU with its connector. Unfortunately, you have to access to the side of the ECU that is against the firewall. Remove the two screws at the top and bottom of the ECU and gently turn it to get to the Model Selector and RED L.E.D. Don't unplug the ECU to do this!

BE CAREFUL!

There should be a small sticker by the Mode Selector that tells you to turn it clockwise to set the Modes and to be sure to return it all the way counter-clockwise to the original position when the car is in use. You will also see the RED L.E.D. inside the ECU.

IF YOUR STICKER IS GONE:

Mark the original position of the Mode Selector. This is a VERY IMPORTANT position for the Mode Selector! (This should be fully counter-clockwise).

2.The Diagnostic Modes

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There are 2- Modes and 2- Conditions for the Engine to be in for running diagnostics:

(NOTE: Mode 1 is a default mode. Your car is always in mode 1 when you are driving(unless you put it into mode2). Mode 1 basically just means computer is on.)

All Modes are with the Ignition Switch in the ON positionMode I (Engine OFF)- Bulb Check- ie checking to see if bulb is burnt out. Mode I (Engine ON) - Malfunction Warning-this is just normal driving.Computer automatically stores any fault codes that occur.Mode II (Engine OFF)- reading Stored Self Diagnostic Results-turning screw to retrieve coesMode II (Engine ON)- Exhaust Gas Sensor Monitor(Exhaust gas sensor is the oygen sensor)

Note: The ECU will automatically return to Mode I when the ignition is switched OFF. When the ECU is changed from Mode II back to Mode I by using the Mode Selector, the malfunction code(s) stored for Mode II will be erased. More on this later.

3. Changing Modes

Note: Switching Modes is not possible when the engine is running.

* Turn the Ignition Switch ON.* The ECU is now in Mode I.* To switch to Mode II:

Turn the ECU Mode Selector fully CLOCKWISE, hold for at least 2-seconds and then return the Mode Selector to it's original position. You are now in Mode II. * Return to Mode I by turning the Mode Selector fully CLOCKWISE again, holding for another 2-seconds and turning it back to the original position.

Note: Doing this will ERASE any Malfunction Codes that are stored in the ECU for Mode II.

Example: If you found a Malfunction Code of 34 when you very first switched to Mode II and then cycled back to Mode I, then again to Mode II, you'll get a 55 (everything's OK) code. This is assuming that you didn't start the car between changing modes. When you start the engine, any current malfunction codes will be store by the ECU until you erase them or they get dumped.

Malfunction Codes are stored by the ECU for 50 times of cranking the starter. Then they are erased. If the same conditions are present, the Malfunction Code will be stored again for 50 cranks of the starter. And so on...

4. Reading the Malfunction Codes:

The Malfunction Codes are indicated by the number of flashes by the RED L.E.D. and the Check Engine Light. You can read either one. They flash the same information. For example, when the RED L.E.D. flashes once and after a short pause flashes twice, this signifies the number "12".

Note: If you find that your looking at a RED L.E.D. and a GREEN L.E.D., you've got a different ECU than is described here. See the FAQ on this same page that was written by Richard Lestage for the SOHC ECU!

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ALL TESTS ARE PERFORMED W/ THE IGNITION SWITCH "ON"

Mode I (Engine OFF)- Bulb Check:

In this Mode, the RED L.E.D. in the ECU and the Check Engine Light stay ON. If either remain OFF, check the bulb. Again, this is just checking to see if warning bulb is burnt out.

Mode I (Engine ON)

RED L.E.D. ON = The ECU's CPU or the Crank Angle sensor is malfunctioning.

(NOTE: Red light does not come on for any of the codes other than crank angle sensor)

**California is different. The light will be on for several of the codes in mode 1.

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Mode II (Engine OFF)- Stored Self Diagnostic Results

Code # Description

11 + Crank angle sensor circuit12 Air flow meter circuit13 Engine temperature sensor circuit14 Vehicle speed sensor circuit21 + Ignition signal circuit31 E.C.U. (E.C.C.S. control unit)32 * EGR function33 Exhaust gas O2 sensor circuit34 Detonation sensor circuit35 * Exhaust gas temperature circuit43 Throttle position sensor circuit45 Injector leak( or a rich condition that cant be corrected)54 Signal circuit from A/T control unit to ECU (A/T only)55 No malfunction in the above circuits

* = California models only

+ = Check items causing a malfunction of the crank angle sensor 1st, if both #11 and #21 are displayed at the same time. Mode II (Engine ON)- Exhaust Gas Sensor Monitor

* Warm up the engine and see that the Temperature Gauge is in it's usual position.(important to get it completely warmed up)

* Run the engine at about 2,000 RPM for about 2- minutes under no-load conditions.

* Make sure the RED L.E.D. or the Check Engine Light goes ON and OFF more than 5- times every 10- seconds; measured at 2,000 RPM under no-load. (This is easiest to do while sitting in the driver's seat and watching the Check Engine Light.)

After the diagnostic, Turn the ignition 'off' to return to mode I.

Modified by vancouverbc at 7:30 PM 2/12/2008
Modified by vancouverbc at 7:48 PM 2/12/2008

hey i have a question? i have a 91 hatch and i keep getting a code of 12 one long and 2 shorts. well here is the prblem with the ignition on i checked for codes and thats what i pulled but when i go to erase them they do not erase just the same codes over and over again. and no i did not start the car in between and yes the car runs like **** like a horrible misfire.

Very informative! Sticky?

are the codes the same for a single cam?????

negative

would anyone happen to have a link to single cam codes?

look up codes in tutorial link in my signature

very useful but it only has 1 of my 3 codes i have

just a heads up information. if your car is japanese like mine. it was on the passenger side.. which would be the left side. might wanna re edit and add that in.

it says its on the left side if your car is rhd