Mirage L4-1597cc 1.6L DOHC Turbo (1989)
Engine Control Module: Component Tests and General Diagnostics
When checking or correcting engine component malfunctions, check basic engine components prior to troubleshooting the Electronic Control Unit (refer
to ON-BOARD DIAGNOSTICS).
To test the Electronic Control Unit (ECU), located on the right side of the passenger compartment below the dash, proceed as follows:
1.
Using the procedures contained in ON-BOARD DIAGNOSTICS extract all malfunction codes. Diagnosis memory is erased if the battery or the
ECU connector is disconnected. Do not disconnect the battery before the trouble codes are completely read. When battery voltage is low, trouble
codes cannot be read. If a sensor connector is disconnected with the ignition switch turned on, the diagnosis code is memorized. Be sure to check
the battery for voltage and other conditions before starting the test.
On-Board Diagnostics Check Terminal Location
2.
Does the ECU output a steady 12 VDC at the diagnostic check connector? If so replacement of the ECU is required.
ECU Probing Technique
To test pins using a multi-meter do not remove the connector from the ECU, instead insert a straight pin or needle from the back side of the connector to
access each pin.
NOTE: Before replacing an ECU that is found to be faulty, insure that no other condition exists that will damage the new unit. This can be best
done by testing the inputs and outputs to the ECU for over voltage/inappropriate power readings or grounds. Use the ECU Terminal Identification
image and the individual component testing procedures to Identify the correct readings for each pin. Check all pins (at the harness with the ECU
removed) that supply a signal to the ECU, for their correct readings and check all other pins to insure that there are no uncalled for voltage readings
or grounds present.
3.
Compare all the remaining codes to the following list and perform the required inspections called for in each of the categories that are affected by a
code.
Check power supply for:
1. Faulty battery.
2. Faulty fusible link.
3. Faulty fuse.
4. Check for faulty body ground.
Check Fuel supply for:
1. Damaged fuel line.
2. Clogged or damaged fuel filter.
3. Faulty fuel pump.
Check ignition system for:
1. Faulty spark plugs.
