DTC P3124-1F: Lost Communication between Drive Motor "A" and HV ECU Circuit Intermittent; DTC P3124-87: Lost Communication between Drive Motor "A" and HV ECU Missing Message [12/2019 - 11/2023]: Procedure

1. Clear the DTCs.

   Powertrain > Motor Generator > Clear DTCs 

2. Turn the ignition switch off.

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  2

1. Read the diagnosis related information and check for DTCs.

   Powertrain > Motor Generator > Utility 

   Tester Display
   Diagnosis Related Information

   Powertrain > Motor Generator > Trouble Codes 

   Result

   Result	Proceed to
   P3124-1F or P3124-87 is listed in Diagnosis Related Information or P3124-1F or P3124-87 is output.	A
   P3124-1F and P3124-87 are not listed in Diagnosis Information and P3124-1F and P3124-87 are not output.	B

2. Turn the ignition switch off.

Result: 

B 

CHECK FOR INTERMITTENT PROBLEMS 

Refer to CHECK FOR INTERMITTENT PROBLEMS [12/2019 - 11/2023]

Result: 

A 

See step  3

1. Connect an oscilloscope between the hybrid vehicle control ECU terminals specified in the following table.
2. Turn the ignition switch to ON.
3. Measure the waveform.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a

   Component with harness connected (Hybrid Vehicle Control ECU)

   -

   -

   Item	Contents
   Tester Connection	CH1: A31-4 (HMCH) - H67-3 (E1) CH2: A31-14 (HMCL) - H67-3 (E1)
   Condition	Ignition switch ON

   Result

   Result	Proceed to
   The waveform appears as shown in the illustration.	A
   The waveform differs from the one shown in the illustration.	B

   HINT: 

   • Perform this inspection with the connector connected.
   • If pulses are generated, the shape of the waveform can be assumed to be normal.
   • The shape of the waveform may vary according to communication conditions.
4. Turn the ignition switch off.

Result: 

A 

REPLACE INVERTER WITH CONVERTER ASSEMBLY 

Refer to REMOVAL [12/2019 - 10/2022] , or refer to REMOVAL [10/2022 - 11/2023]

Result: 

B 

See step  4

1. Check the connector connections and contact pressure of the relevant terminals for the hybrid vehicle control ECU connectors.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Refer to ELECTRONIC CIRCUIT INSPECTION PROCEDURE [12/2019 - ]

   OK

   The connectors are connected securely and there are no contact pressure problems.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

CONNECT SECURELY 

Result: 

OK 

See step  5

1. Check that the service plug grip is not installed.
   NOTE:

   After removing the service plug grip, do not turn the ignition switch to ON (READY), unless instructed by the repair information because this may cause a malfunction.

2. Check the connection condition of the low voltage connectors of the inverter with converter assembly and the contact pressure of each terminal. Check the terminals for deformation, and the connector for water and foreign matter.

   Refer to ELECTRONIC CIRCUIT INSPECTION PROCEDURE [12/2019 - ]

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   NOTE:

   Before disconnecting the connector, confirm that it is properly connected by checking that the claws of the lock levers are engaged and that the connector cannot be pulled off.

   OK

   - The connector is connected securely.

   - The terminals are not deformed and are connected securely.

   - No water or foreign matter in the connector.

   Result

   Result	Proceed to
   OK	A
   NG (The connector is not connected securely.)	B
   NG (The terminals are not making secure contact or are deformed, or water or foreign matter exists in the connector.)	C

   HINT: 

   When connecting the connector, connect it with the lock levers raised. Rotate each lock lever downward and make sure that the connector is securely connected. When a lock lever is fully lowered, a click will be heard as its claw engages. After the click is heard, pull up on the connector to confirm that it is securely connected.

Result: 

B 

CONNECT SECURELY 

Result: 

C 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

A 

See step  6

1. Check that the service plug grip is not installed.
   NOTE:

   After removing the service plug grip, do not turn the ignition switch to ON (READY), unless instructed by the repair information because this may cause a malfunction.

2. Disconnect the A55 inverter with converter assembly connector.
3. Disconnect the A31 hybrid vehicle control ECU connector.
4. Measure the resistance according to the value(s) in the table below.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to Inverter with Converter Assembly)
   *b	Front view of wire harness connector (to Hybrid Vehicle Control ECU)

   Standard Resistance (Check for Open)

   Tester Connection	Condition	Specified Condition
   A55-3 (HMCH) - A31-4 (HMCH)	Ignition switch off	Below 1 Ω
   A55-4 (HMCL) - A31-14 (HMCL)	Ignition switch off	Below 1 Ω

   Standard Resistance (Check for Short)

   Tester Connection	Condition	Specified Condition
   A55-3 (HMCH) or A31-4 (HMCH) - Body ground and other terminals	Ignition switch off	10 kΩ or higher
   A55-4 (HMCL) or A31-14 (HMCL) - Body ground and other terminals	Ignition switch off	10 kΩ or higher

5. Connect the cable to the negative (-) auxiliary battery terminal.
6. Turn the ignition switch to ON.
7. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A55-3 (HMCH) or A31-4 (HMCH) - Body ground and other terminals	Ignition switch ON	Below 1 V
   A55-4 (HMCL) or A31-14 (HMCL) - Body ground and other terminals	Ignition switch ON	Below 1 V

   NOTE:

   Turning the ignition switch to ON with the hybrid vehicle control ECU and inverter with converter assembly connectors disconnected causes other DTCs to be stored. Clear the DTCs after performing this inspection.

8. Turn the ignition switch off.
9. Reconnect the A31 hybrid vehicle control ECU connector.
10. Reconnect the A55 inverter with converter assembly connector.

    Result

    Proceed to
    OK
    NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  7

1. Disconnect the A31 hybrid vehicle control ECU connector.
2. Measure the resistance according to the value(s) in the table below.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to Hybrid Vehicle Control ECU)

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A31-4 (HMCH) - A31-14 (HMCL)	Ignition switch off	80 to 170 Ω

3. Reconnect the A31 hybrid vehicle control ECU connector.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE HYBRID VEHICLE CONTROL ECU 

Refer to REMOVAL [12/2019 - 10/2022] , or refer to REMOVAL [10/2022 - 11/2023]

Result: 

NG 

REPLACE INVERTER WITH CONVERTER ASSEMBLY 

Refer to REMOVAL [12/2019 - 10/2022] , or refer to REMOVAL [10/2022 - 11/2023]