[Previous][Next]
DTC P1A4C: OR Line Voltage
 
 
cautionWhenever ECU is replaced, ensure that the CAN bus lines are normal.
 
 
TROUBLE JUDGMENT
Check Condition
  • The power supply mode of the electric motor switch is ON, or the main drive lithium-ion battery starts to be charged.
Judgment Criterion
  • The abnormal battery management unit (BMU) control power supply voltage is detected.
 
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • Not available
 
 
PROBABLE CAUSES
  • The 12V starter battery is failed.
    noteWhen using the higher voltage from the outside of the vehicle than the voltage of the 12V starter battery
  • The installation of the 12V starter battery terminal is failed.
  • Open circuits of battery management unit (BMU) control power supply circuit, short circuits to ground or damage; poor contact of connector
  • The battery management unit (BMU) is failed.
 
 
 
 
DIAGNOSIS
Required Special Tools
  • MB991658: Test harness
STEP 1. Using scan tool (M.U.T.-IIISE), check whether the other DTC is set.
Is the DTC P0A09 related to PHEV-ECU system set?
Check PHEV-ECU system (Refer to GROUP 54Da - PHEV-ECU - Diagnostic Trouble Code Chart ).
Go to Step 2.
 
STEP 2. 12V starter battery condition check
Is the installation status of the 12V starter battery terminal normal?
Go to Step 3.
Repair.
 
STEP 3. Check 12V starter battery
Check 12V starter battery (Refer to GROUP 54A - 12V Starter Battery, On-vehicle Service, Battery Test ).
Is the check result normal?
Go to Step 4.
Replace the 12V starter battery.
 
STEP 4. Measure the voltage at battery management unit (BMU) connector
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Check the voltage between the battery management unit (BMU) connector (BAT terminal) and body ground.
OK: Battery voltage
Is the check result normal?
Go to Step 5.
  • Repair BAT line between 12V starter battery and BMU connector.
 
STEP 5. Measure the voltage at battery management unit (BMU) connector (IGCT terminal).
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Turn on the power supply mode of the electric motor switch.
(3) Check the voltage between the battery management unit (BMU) connector (IGCT terminal) and body ground.
OK: Battery voltage
(4) Turn off the power supply mode of the electric motor switch.
Is the check result normal?
Go to Step 6.
Repair IGCT line between relay box 3 (engine compartment) and BMU connector.
 
STEP 6. Measure the resistance at battery management unit (BMU) connector (GND terminal).
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Check the resistance between the battery management unit (BMU) connector (GND terminal) and body ground.
OK: Continuity exists (2 Ω or less)
Is the check result normal?
Go to Step 7.
Repair IGCT line between relay box 3 (engine compartment) and BMU connector.
 
STEP 7. Using scan tool (M.U.T.-IIISE), check whether the DTC is set again.
Recheck the DTC.
(1) Erase the DTC.
(2) Turn off the power supply mode of the electric motor switch.
(3) Turn on the power supply mode of the electric motor switch.
(4) Check the DTC.
Is the DTC set?
Replace the battery management unit (BMU) (Refer to ).
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).