Mirage L4-1597cc 1.6L DOHC (1990)
Engine Control Module: Component Tests and General Diagnostics
Electronic Control Unit (ECU) Location
When checking or correcting engine component malfunctions, check basic engine components prior to troubleshooting the Electronic Control Unit.
See: Testing and Inspection/Reading and Clearing Diagnostic Trouble Codes
To test the Electronic Control Unit (ECU), located on the right side of the passenger compartment below the dash, proceed as follows:
NOTE: Diagnostic memory is erased if the battery or the ECU connector is disconnected. Do not disconnect the battery before the trouble codes
are completely read. If a sensor connector is disconnected with the ignition switch turned on, the diagnosis code is memorized. In this case,
disconnect the battery negative terminal for 15 seconds or more, and all diagnostic memory will be erased.
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. See: Testing and Inspection/Reading
and Clearing Diagnostic Trouble Codes
CAUTION: When battery voltage is low, trouble codes cannot be read. Be sure to check the battery for voltage and other conditions before starting
the test.
On-Board Diagnostics Check Connector Location
2.
Does the ECU output a steady 12 VDC at the diagnostic check connector?
a. If not, and the ECU is suspected to be faulty, check the ECU power and ground circuits.
b. If so replacement of the ECU is required.
ECU Probing Technique
