Reading Diagnostic Trouble Codes

PRE-TEST CONDITIONS:

Prior to performing any type of diagnosis or testing of this system, ensure that all other related systems that can affect the operation of the MPI system have been checked and determined to be functioning properly.
Ensure battery is fully charged, as detection of an abnormality cannot be made if battery voltage is low. Diagnosis item is erased if power supply from battery or ECU connector is disconnected. Do not disconnect power supply before diagnosis result is completely read.
Before the oxygen sensor can be diagnosed, engine must be at normal operating temperature. Also, do not place ignition switch in Off position after warming up engine. If ignition switch is turned to Off position, the result detected by diagnosis of sensor is erased.

Fig. 3 MPI diagnosis test connection.:

EXTRACTING CODES:

1. Turn ignition switch to Off position, then open glove compartment and locate the diagnostic connector.
2. Connect suitable voltmeter between ``MPI'' and ground terminal, Fig. 3.
3. Turn ignition switch to On position. An indication of ECU memory will immediately begin. If system is in a normal condition, pointer of voltmeter will indicate a steady 12 volts. If an abnormal condition is stored in the memory, the pointer of the voltmeter will deflect between 0 and 12 volts.
4. Record the number of deflections of the voltmeter and compare the results with the diagnostic codes chart.
5. Turn ignition switch to Off position, then clear trouble code(s) from memory as described in ``Clearing Diagnostic Codes'' procedure.