To pull the fault codes from the ECU memory, perform the following:
1 Using a jumper lead with a on-off switch, ground the single pin test socket on the driver's side under the hood. The test socket consists of three test attaching plugs - round, square w/4 plugs, and L-shaped w/4 plugs. The grounding pin is attached to the toe plug of the L-shaped w/4 plugs.
2. Switch on the ignition. The CHECK ENGINE light will now come on.
3. Set the switch to ON which provides ground to ECU pin 16 signaling the ECU to send the fault codes. The CHECK ENGINE light will now turn off.
4. Watch the CHECK ENGINE light carefully. After about 2.5 seconds, it will flash briefly, signifying that the first code will now be displayed. As soon as the light has flashed, move the grounding switch that you have set-up immediately to the OFF position.
5. The first of three possible error codes will now be displayed by a series of short flashes of the CHECK ENGINE light. Note that the error code series starts and finishes with a long flash of the CHECK ENGINE light. These long flashes are not part of the code itself, but serve to indicate the beginning and end of the code.
6. Each short flash of the CHECK ENGINE light is counted as a "1". The sum of the short flashes indicates the digits number. When the switch is set to OFF, the error code will be flashed repeatedly. The next error code cannot be displayed until the switch has been set to the ON position. Note that if the test is run with the engine not running, the first code displayed will be 12231 (no rpm signal).
7. To retrieve the next error code, set the switch to ON. After a short flash of the CHECK ENGINE light, set the switch back to the OFF position. The next error code will now be displayed in a series of flashes.
8. Follow the same procedure to display the error code for the third fault, if any. If no third fault has been detected or all the faults have been fixed, the system will indicate this by a continuous series of five long flashes (00000).
9. To delete the memory contents, set the switch to ON. After three short flashes, set the switch to OFF. Note that the memory contents cannot be deleted until all codes have been read and code 00000 has been displayed.