Sonata V6-3.0L (1991)
Electronic Control Unit: Testing and Inspection
NOTE: When checking or correcting engine component malfunctions, check basic engine components prior to troubleshooting the Electronic
Control Unit (refer to ON-BOARD DIAGNOSTICS).
ECU Location
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.
NOTE: 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.
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.
2.
Does the ECU output a steady 12 vdc at the check connector? If so replacement of the ECU is required.
