[Previous][Next]
Inspection Procedure 7: The 12V starter battery becomes flat frequently.
 
 
cautionBefore replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
 
 
TECHNICAL DESCRIPTION (COMMENT)
When the 12V starter battery becomes flat frequently, the permission conditions for charging the 12V starter battery are not satisfied, the CHOT (EV start signal), the DC/DC converter, the 12V starter battery, the PHEV-ECU or the EV remote-ECU may be defective or deteriorated.
 
 
TROUBLESHOOTING HINTS
  • Permission conditions for charging the 12V starter battery not satisfied
  • The CAN bus line may be defective (The CHOT signal fails)
  • The DC/DC converter may be defective
  • 12V starter battery deteriorated
  • The PHEV-ECU may be defective
  • The EV remote-ECU may be defective
 
 
DIAGNOSIS
STEP 1. 12V starter battery check
Perform the basic checks (loose terminals, corrosion and battery test).
Is the check result normal?
Go to Step 2.
Charge the 12V starter battery, or replace a defective component.
 
STEP 2. 12V starter battery charging condition check
Measure the voltages at the 12V starter battery terminals when the power supply mode of the electric motor switch is turned on and off. Compare the two measured values. When it is turned on, the voltage should rise (reference value: 13.5 volts or more).
Is the check result normal?
Go to Step 3.
Troubleshoot the PHEV-ECU (Refer to GROUP 54Da - Troubleshooting ).
 
STEP 3. Check whether permission conditions for charging the 12V starter battery are satisfied.
Check whether permission conditions for charging the 12V starter battery are satisfied (Refer to ).
Is the check result normal?
Go to Step 4.
Satisfy the conditions (Refer to ).
 
STEP 4. Using scan tool (M.U.T.-IIISE), diagnose the CAN bus line.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn off the power supply mode of the electric motor switch before connecting or disconnecting scan tool (M.U.T.-IIISE).
Connect scan tool (M.U.T.-IIISE). Refer to "How to connect the Scan Tool (M.U.T.-IIISE) ."
(2) Press the electric motor switch to turn on the power supply mode.
(3) Diagnose the CAN bus line.
(4) Press the electric motor switch to turn off the power supply mode.
Is the CAN bus line found to be normal?
Go to Step 5.
Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting ).
 
STEP 5. Using scan tool (M.U.T.-IIISE), check the DTC.
Check if DTC is set in the EV remote-ECU.
Is the DTC set?
Troubleshoot the EV remote-ECU (Refer to ).
Go to Step 6.
 
STEP 6. Using scan tool (M.U.T.-IIISE), read the other system DTC.
Check if DTC is set in the DC/DC converter or PHEV-ECU.
Is the DTC set?
: Troubleshoot the DC/DC converter (Refer to GROUP 54Dd - Troubleshooting ).
: Troubleshoot the PHEV-ECU (Refer to GROUP 54Da - Troubleshooting ).
Go to Step 7.
 
STEP 7. Using scan tool (M.U.T.-IIISE), check the actuator test.
(1) Perform the following actuator tests (Refer to ).
  • Item No.3: Circuit fault detection
(2) Check if DTC is set.
Is the DTC set?
Troubleshoot the EV remote-ECU (Refer to ).
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).