Many malfunctions in the electrical system are caused by poor harness(es) and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
Has a problem been found?
YES
Repair as necessary and then go to "Verification of Vehicle Repair" procedure.
NO
Verify presence of battery voltage codes in other ECUs (SRS, etc).
If battery voltage codes are not present in other ECUs, go to "Power Circuit Inspection" procedure.
If battery voltage codes are present in other ECUs, go to "Alternator Output Voltage Inspection" procedure.
Ignition "ON" & Engine "ON".
Measure voltage between the battery terminal(+) and the battery terminal(-) with maintaining ENG RPM 2,500RPM over 2 minutes.
Specification : Below. 18 ± 1.0V
Is the measured voltage within specifications?
YES
Go to "Power Circuit Inspection" procedure.
NO
Check that the tension of driving velt, ENG RPM, fuse, terminal of battery, all terminals of alternator are in good condition and Check for damaged harness and poor connection between alternator and battery.
If OK repair or replace alternator and then go to "Verification of vehicle Repair" procedure.
Ignition "ON" & Engine "OFF".
Measure voltage between the battery terminal(+) and terminal "28(ESP), 18(ABS)" of the HECU harness connector.
Specification : Approx. below 0.2V
Is the measured voltage within specifications?
YES
Go to "Ground Circuit Inspection" procedure.
NO
Check for damaged harness and poor connection between the battery terminal(+) and terminal "28(ESP), 18(ABS)" of the HECU harness connector. Repair as necessary and then go to "Verification of vehicle Repair" procedure.
Ignition "OFF".
Disconnect HECU connector.
Measure resistance between terminal "4" of the HECU harness connector and chassis ground.
Specification : Approx. below 1Ω
Is the measured resistance within specifications?
YES
Substitute with a known-good HECU and check for proper operation. If problem is corrected, replace HECU and then go to "Verification of Vehicle Repair" procedure.
NO
Check for damaged harness and poor connection between terminal "4" of the HECU harness connector and chassis ground. Repair as necessary and then go to "Verification of vehicle Repair" procedure.
