Toyota Avalon (XX50): Lost Communication between Drive Motor "A" and HV ECU Circuit Intermittent (P31241F,P312487)

DESCRIPTION

The motor generator control ECU, which is built into the inverter with converter assembly, controls the motor (MG2) based on commands from the hybrid vehicle control ECU.

The motor generator control ECU (MG ECU) monitors communication data and detects malfunctions.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Warning Indicate
P31241F	Lost Communication between Drive Motor "A" and HV ECU Circuit Intermittent	Error in reception from hybrid vehicle control ECU via serial communication (out of communication standard) detected when DTC P0C7917, P0D3319, P1C5D19 or P1C5F19 is stored. (1 trip detection logic)	Wire harness or connector Inverter with converter assembly Hybrid vehicle control ECU	Does not come on	Master Warning Light: Does not come on
P312487	Lost Communication between Drive Motor "A" and HV ECU Missing Message	Error in reception from hybrid vehicle control ECU via serial communication (out of communication standard) (1 trip detection logic)	Wire harness or connector Inverter with converter assembly Hybrid vehicle control ECU	Comes on	Master Warning Light: Comes on

MONITOR DESCRIPTION

If the motor generator control ECU detects a communication malfunction between it and the hybrid vehicle control ECU, it will illuminate the MIL and store a DTC.

MONITOR STRATEGY

Related DTCs	P3124 (INF P312487): Lost Communication With Hybrid Control Module (Hybrid Control Module, Drive Motor "A" bus)
Required sensors/components	Motor generator control ECU Hybrid vehicle control ECU
Frequency of operation	Continuous
Duration	TMC's intellectual property
MIL operation	Immediately
Sequence of operation	None

TYPICAL ENABLING CONDITIONS

The monitor will run whenever the following DTCs are not stored	TMC's intellectual property
Other conditions belong to TMC's intellectual property	-

TYPICAL MALFUNCTION THRESHOLDS

TMC's intellectual property

-

COMPONENT OPERATING RANGE

Motor generator control ECU

DTC P3124 (INF 312487) is not detected

CONFIRMATION DRIVING PATTERN

HINT:

• After repair has been completed, clear the DTC and then check that the vehicle has returned to normal by performing the following All Readiness check procedure.

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• When clearing the permanent DTCs, refer to the "CLEAR PERMANENT DTC" procedure.

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1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG) and turn the Techstream on.
3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
4. Turn the power switch off and wait for 2 minutes or more.
5. Turn the power switch on (IG) and turn the Techstream on.
6. With power switch on (IG) and wait for 2 minutes or more. [*1]

   HINT:

   [*1]: Normal judgment procedure.

   The normal judgment procedure is used to complete DTC judgment and also used when clearing permanent DTCs.

7. Enter the following menus: Powertrain / Motor Generator / Utility / All Readiness.
8. Check the DTC judgment result.

   HINT:

   • If the judgment result shows NORMAL, the system is normal.
   • If the judgment result shows ABNORMAL, the system has a malfunction.
   • If the judgment result shows INCOMPLETE or N/A, perform the normal judgment procedure again.

WIRING DIAGRAM

Refer to the wiring diagram for the Inverter Low-voltage Circuit.

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CAUTION / NOTICE / HINT

CAUTION:

• Before the following operations are conducted, take precautions to prevent electric shock by turning the power switch off, wearing insulated gloves, and removing the service plug grip from HV battery.
  • Inspecting the high-voltage system
  • Disconnecting the low voltage connector of the inverter with converter assembly
  • Disconnecting the low voltage connector of the HV battery
• To prevent electric shock, make sure to remove the service plug grip to cut off the high voltage circuit before servicing the vehicle.
• After removing the service plug grip from the HV battery, put it in your pocket to prevent other technicians from accidentally reconnecting it while you are working on the high-voltage system.
• After removing the service plug grip, wait for at least 10 minutes before touching any of the high-voltage connectors or terminals. After waiting for 10 minutes, check the voltage at the terminals in the inspection point in the inverter with converter assembly. The voltage should be 0 V before beginning work.

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  HINT:

  Waiting for at least 10 minutes is required to discharge the high-voltage capacitor inside the inverter with converter assembly.

  

  *a	Without waiting for 10 minutes

NOTICE:

After turning the power 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.

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PROCEDURE

1.

CLEAR DTC

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Motor Generator / Trouble Codes.

(e) Clear the DTCs.

Powertrain > Motor Generator > Clear DTCs

(f) Turn the power switch off.

NEXT

2.	CHECK DIAGNOSIS RELATED INFORMATION AND DTC OUTPUT (MOTOR GENERATOR CONTROL)

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Enter the following menus: Powertrain / Motor Generator / Utility / Diagnosis Related Information.

Powertrain > Motor Generator > Utility

Tester Display
Diagnosis Related Information

(d) Enter the following menus: Powertrain / Motor Generator / Trouble Codes.

Powertrain > Motor Generator > Trouble Codes

(e) Check for DTCs.

Result	Proceed to
P31241F or P312487 is listed in Diagnosis Related Information or DTC P31241F or P312487 is output.	A
P31241F and P312487 is not listed in Diagnosis Information and DTC P31241F and P312487 is not output.	B

(f) Turn the power switch off.

B

CHECK FOR INTERMITTENT PROBLEMS

A

3.	CHECK HYBRID VEHICLE CONTROL ECU (CHECK WAVEFORM)

(a) Connect an oscilloscope between the hybrid vehicle control ECU terminals specified in the following table.

(b) Turn the power switch on (IG).

(c) Measure the waveform. Item Contents Tester Connection CH1: A24-31 (HMCH) - G46-6 (E1) CH2: A24-30 (HMCL) - G46-6 (E1) Equipment Setting 1 V/DIV., 200 μs./DIV. Condition Power switch on (IG) 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.

*a Component with harness connected (Hybrid Vehicle Control ECU)

(d) Turn the power switch off.

A

REPLACE INVERTER WITH CONVERTER ASSEMBLY

B

4.	CHECK CONNECTOR CONNECTION CONDITION (HYBRID VEHICLE CONTROL ECU CONNECTOR)

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NG

CONNECT SECURELY

OK

5.	CHECK CONNECTOR CONNECTION CONDITION (INVERTER WITH CONVERTER ASSEMBLY CONNECTOR)

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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

B

CONNECT SECURELY

C

REPAIR OR REPLACE HARNESS OR CONNECTOR

A

6.	CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - INVERTER WITH CONVERTER ASSEMBLY)

CAUTION:

Be sure to wear insulated gloves.

(a) Check that the service plug grip is not installed.

NOTICE:

After removing the service plug grip, do not turn the power switch on (READY), unless instructed by the repair manual because this may cause a malfunction.

(b) Disconnect the A42 inverter with converter assembly connector.

(c) Disconnect the A24 hybrid vehicle control ECU connector.

(d) Measure the resistance according to the value(s) in the table below. Standard Resistance (Check for Open): Tester Connection Condition Specified Condition A42-20 (HMCH) - A24-31 (HMCH) Power switch off Below 1 Ω A42-19 (HMCL) - A24-30 (HMCL) Power switch off Below 1 Ω Standard Resistance (Check for Short): Tester Connection Condition Specified Condition A42-20 (HMCH) or A24-31 (HMCH) - Body ground and other terminals Power switch off 10 kΩ or higher A42-19 (HMCL) or A24-30 (HMCL) - Body ground and other terminals Power switch off 10 kΩ or higher

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

(e) Connect the cable to the negative (-) auxiliary battery terminal.

(f) Turn the power switch on (IG).

(g) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection	Condition	Specified Condition
A42-20 (HMCH) or A24-31 (HMCH) - Body ground and other terminals	Power switch on (IG)	Below 1 V
A42-19 (HMCL) or A24-30 (HMCL) - Body ground and other terminals	Power switch on (IG)	Below 1 V

NOTICE:

Turning the power switch on (IG) 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.

(h) Turn the power switch off.

(i) Reconnect the A24 hybrid vehicle control ECU connector.

(j) Reconnect the A42 inverter with converter assembly connector.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

7.	CHECK INVERTER WITH CONVERTER ASSEMBLY

(a) Disconnect the A24 hybrid vehicle control ECU connector.

(b) Measure the resistance according to the value(s) in the table below. Standard Resistance: Tester Connection Condition Specified Condition A24-31 (HMCH) - A24-30 (HMCL) Power switch off 80 to 170 Ω

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

(c) Reconnect the A24 hybrid vehicle control ECU connector.

OK

REPLACE HYBRID VEHICLE CONTROL ECU

NG

REPLACE INVERTER WITH CONVERTER ASSEMBLY