The ECM provides ground to one side of the coil of the main relay and the other side is connected to the battery. The ECM monitors battery voltage and the voltage after the main relay.
During engine running, if system voltage is above 16V, PCM sets P0563. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.
Item | Detecting Condition | Possible cause | |
DTC Strategy | ● Voltage too high | ● Poor connection ● Short in circuit ● Faulty charging system ● Faulty main relay ● Faulty PCM | |
Enable Conditions | ● Engine works | ||
Thresh old value | ● System voltage 〉16V | ||
Diagnosis Time | ● Continuous | ||
MIL On Condition | ● 2 driving cycles |
Coil Resistance | 70Ω ~ 120Ω |
Check DTC Status
Connect scantool to Data Link Connector(DLC).
IG "ON".
Select "Diagnostic Trouble Codes(DTCs)" mode, and then Press F4(DTAL) to check DTC's information from the DTCs menu
Read "DTC Status" parameter.
Is parameter displayed "Present fault"?
▶ Go to "Terminal and connector inspection" procedure.
▶ Fault is intermittent caused by poor contact in the sensor’s and/or PCM’s connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
Many malfunctions in the electrical system are caused by poor harness 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?
▶ Repair as necessary and go to "Verification of Vehicle Repair" procedure
▶ Go to " Power Circuit Inspection " procedure.
Check voltage
IG "OFF".
Disconnect the main relay.
IG "ON" and ENG "OFF"
Measure the voltage between terminal 30 of main relay harness connector and chassis ground.
Measure the voltage between terminal 85 of main relay harness connector and chassis ground.
Specification : B+
Is the measured voltage within specification ?
▶ Go to "Check short in harness" procedure.
▶ Repair Short in power harness and go to "Verification of Vehicle Repair" procedure.
Check short in harness
IG "ON".
Measure the voltage between terminal 38, 39, 40 of PCM harness terminal and chassis ground.
Specification : B+
Is the measured voltage within specification ?
▶ Go to "System inspection" procedure.
▶ Repair short in power harness and go to "Verification of Vehicle Repair" procedure .
Check Alternator circuit
IG "OFF".
Disconnect alternator connector.
IG "ON" and ENG "OFF"
Measure the voltage between terminal 2 of alternator and chassis gound.
Measure the voltage between terminal 3 of alternator and chassis gound.
Specification : B+
Is the measured voltage within specification?
▶ Go to "Component inspection" procedure.
▶ Repair short in sensing circuit or MIL circuit and go to "Verification of Vehicle Repair" procedure.
Check Main relay
IG "OFF".
Disconnect the main relay.
Measure the resistance between terminal 30 and 87 of main relay.
Measure the resistance between terminal 85 and 86 of main relay.
Specification : 70 ~ 120Ω
Terminal | Power approval |
30~87 | NO |
85~86 | YES (Approx. 70Ω ~ 120Ω) |
Is the measured resistance within specification ?
▶ Substitute with a known - good PCM and check for proper operation. If the problem is corrected, replace PCM and go to "Verification of Vehicle Repair" procedure.
▶ Substitute with a known - good Main relay and check for proper operation. If the problem is corrected, replace Main relay and go to "Verification of Vehicle Repair" procedure.
There is a memory reset function on scantool that can erase optional parts automatically detected and memorized by PCM. After testing PCM on the vehicle, use this function to reuse the PCM on the others
Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode
Press F4(DTAL) and confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions
Read "DTC Status" parameter
Is parameter displayed "History(Not Present) fault"?
▶ System performing to specification at this time. Clear the DTC.
▶ Go to the applicable troubleshooting procedure.