Diagnosis System [12/2019 - 11/2023]

1. The hybrid vehicle control ECU has a self-diagnosis system. If the computer, Hybrid Control System, or a component is not working properly, the ECU records the conditions that relate to the fault. The ECU also illuminates the master warning in the combination meter assembly and provides other appropriate messages on the multi-information display, such as the HV system warning message, HV battery warning message, or discharge warning message.
   • When troubleshooting OBD II (On-Board Diagnostics) vehicles, the GTS (complying with SAE J1978) must be connected to the DLC3 (Data Link Connector 3) of the vehicle. Various data in the vehicle motor generator control ECU can then be read.
   • OBD II regulations require that the vehicle's on-board computer illuminates the MIL (Malfunction Indicator Lamp) on the instrument panel when the computer detects a malfunction in:

     Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

     1. The emission control system components.
     2. The powertrain control components (which affect vehicle emissions).
     3. The computer itself.

        In addition, the applicable DTCs prescribed by SAE J2012 are recorded in the motor generator control ECU memory. If the malfunction does not recur in 3 consecutive trips, the MIL turns off automatically but the DTCs remain recorded in the motor generator control ECU memory.

   • To check for DTCs, connect the GTS to the DLC3. The GTS displays DTCs, Freeze Frame Data, and a variety of Hybrid Control System data. The DTCs and Freeze Frame Data can be cleared with the GTS. In order to enhance the OBD function on vehicles and develop the off-board diagnosis system, Controller Area Network (CAN) communication is used in this system. CAN is a network which uses a pair of data transmission lines spanning multiple computers and sensors. It allows for high speed communications between the systems and simplification of the wire harness connections.

Following is the description for storage of DTC using "2 trip detection logic". 

1. When a malfunction is first detected, the malfunction is temporarily stored in the hybrid vehicle control ECU memory (1st trip). If the same malfunction is detected during the next drive cycle, the MIL is illuminated (2nd trip).

1. The hybrid vehicle control ECU records vehicle and driving condition information as Freeze Frame Data the moment a DTC is stored. When troubleshooting, Freeze Frame Data can be helpful in determining whether the vehicle was moving or stationary, whether the engine was warmed up or not, as well as other data recorded at the time of a malfunction.

Standard Voltage

1. If voltage is below 11 V, recharge or replace the auxiliary battery.
   NOTE:

   After turning the ignition switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work.

   Refer to INITIALIZATION [12/2019 - 09/2020] , or refer to INITIALIZATION [09/2020 - 10/2021] , or refer to INITIALIZATION [10/2021 - 10/2022] , or refer to INITIALIZATION [10/2022 - 11/2023]

1. The MIL is illuminated when the ignition switch is first turned to ON, before the READY light comes on.
2. When the READY indicator turns on, the MIL should turn off. If the MIL remains illuminated, the diagnosis system has detected a malfunction or abnormality in the system.

   HINT: 

   If the MIL is not illuminated when the ignition switch is first turned to ON, check the MIL circuit.

   for SFI System: Refer to MIL Circuit [12/2019 - 10/2022] , or refer to MIL Circuit [10/2022 - 11/2023]

The inspection areas and outline of the inspection for each circuit are listed below.

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• Each DTC diagnostic procedure for the hybrid control system consists of a combination of the various relevant system (circuit) inspections.
• When multiple DTCs are output, performing each diagnostic procedure in order of priority can lead to a more accurate diagnosis.

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT: 

The "Example of Multiple DTCs being Output" below is only one example of a malfunction condition. Therefore, a determination should not be made based on this alone.

Example of Multiple DTCs being Output: 

1. The power supply of the microcomputer decreases while the vehicle is being driven.
   1. DTCs are detected and the vehicle behavior is as follows.

   Detected DTCs 

   • P060B-1C (Hybrid/EV Powertrain Control Module A/D Processing Voltage Out of Range): Microcomputer malfunction*
   • P0688-1F (ECM/PCM Power Relay Sense Circuit Intermittent): Power source circuit malfunction*
   • P0AA7-49 (Hybrid/EV Battery Voltage Isolation Sensor Circuit Internal Electronic Failure): Sensor and actuator circuit malfunction*
   • P0B23-1C (Hybrid/EV Battery "A" Voltage Sensor Voltage Out of Range): Sensor and actuator circuit malfunction*
   • P1C9E-9F (Hybrid/EV System Reset Stuck Off): System malfunction*
     1. *: Check the priority level in the "DTC Order of Priority" chart above.

   Vehicle Behavior 

   1. System stopped
2. The inspection order of priority is: Microcomputer circuit → power source circuit → communication circuit → sensor and actuator circuit → system circuit. Therefore, check the repair procedure for P060B-1C.
3. Follow the repair procedures and replace the hybrid vehicle control ECU. Finish the repair.

It is possible to check only the specified malfunctioning parts without having to check irrelevant parts.