Toyota Avalon (XX50): Lost Communication between Hybrid Powertrain Control Module and Active Grille Air Shutter Missing Message (U129387). VC Output Circuit. Vehicle Control History

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual / Engine / A25a-fxs Engine Control / Sfi System / Lost Communication between Hybrid Powertrain Control Module and Active Grille Air Shutter Missing Message (U129387). VC Output Circuit. Vehicle Control History

Lost Communication between Hybrid Powertrain Control Module and Active Grille Air Shutter Missing Message (U129387)

DESCRIPTION

The swing grille actuator assembly and hybrid vehicle control ECU assembly send and receive signals via CAN communication.

If a communication error occurs between the swing grille actuator assembly and hybrid vehicle control ECU assembly, the ECM stores this DTC.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Memory	Note
U129387	Lost Communication between Hybrid Powertrain Control Module and Active Grille Air Shutter Missing Message	All of the following conditions are met and the ECM receives a malfunction signal 17 times* (1 trip detection logic): Power switch on (IG) The grille shutter is not in winter control mode. No communication between swing grille actuator assembly and hybrid vehicle control ECU assembly	CAN communication system Hybrid vehicle control ECU assembly Swing grille actuator assembly	Comes on	DTC stored	SAE Code: U1293

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

Note

U129387

Lost Communication between Hybrid Powertrain Control Module and Active Grille Air Shutter Missing Message

All of the following conditions are met and the ECM receives a malfunction signal 17 times* (1 trip detection logic):

Power switch on (IG)
The grille shutter is not in winter control mode.
No communication between swing grille actuator assembly and hybrid vehicle control ECU assembly

CAN communication system
Hybrid vehicle control ECU assembly
Swing grille actuator assembly

Comes on

DTC stored

SAE Code: U1293

HINT:

*: For every 65 ms that the ECM receives a grille shutter system malfunction signal from the grille shutter ECU (swing grille actuator assembly) the ECM determines it has received the signal 1 time. If the ECM determines the malfunction signal has been received 17 consecutive times (the signal is received for approximately 1 second continuously), it will store a DTC.

MONITOR STRATEGY

Related DTCs	U1293: Lost communication with hybrid control module
Required Sensors/Components (Main)	Swing grille actuator assembly
Required Sensors/Components (Related)	-
Frequency of Operation	Continuous
Duration	17 times
MIL Operation	Immediate
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever the following DTCs are not stored	None
Both of the following conditions are met	-
Auxiliary battery Voltage	9.5 V or higher
Power switch	On (IG)

TYPICAL MALFUNCTION THRESHOLDS

Communication signal

Lost communication with hybrid control module

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

Connect the Techstream to the DLC3.
Turn the power switch on (IG).
Turn the Techstream on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the power switch off and wait for at least 30 seconds.
Turn the power switch on (IG) [A].
Turn the Techstream on.
Wait 20 seconds or more.
Enter the following menus: Powertrain / Engine / Trouble Codes [B].
Read the pending DTCs.
HINT:
- If a pending DTC is output, the system is malfunctioning.
- If a pending DTC is not output, perform the following procedure.
Enter the following menus: Powertrain / Engine / Utility / All Readiness.
Input the DTC: U129387.

Check the DTC judgment result.

Techstream Display	Description
NORMAL	DTC judgment completed System normal
ABNORMAL	DTC judgment completed System abnormal
INCOMPLETE	DTC judgment not completed Perform driving pattern after confirming DTC enabling conditions

HINT:

If the judgment result shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system is malfunctioning.
[A] to [B]: Normal judgment procedure.
The normal judgment procedure is used to complete DTC judgment and also used when clearing permanent DTCs.
When clearing the permanent DTCs, do not disconnect the cable from the auxiliary battery terminal or attempt to clear the DTCs during this procedure, as doing so will clear the universal trip and normal judgment histories.

CAUTION / NOTICE / HINT

NOTICE:

Vehicle Control History may be stored in the hybrid vehicle control ECU assembly if the engine is malfunctioning. Certain vehicle condition information is recorded when Vehicle Control History is stored. Reading the vehicle conditions recorded in both the Freeze Frame Data and Vehicle Control History can be useful for troubleshooting.
Click here

(Select Powertrain in Health Check and then check the time stamp data.)

Click here
If any "Engine Malfunction" Vehicle Control History item has been stored in the hybrid vehicle control ECU assembly, make sure to clear it. However, as all Vehicle Control History items are cleared simultaneously, if any Vehicle Control History items other than "Engine Malfunction" are stored, make sure to perform any troubleshooting for them before clearing Vehicle Control History.
Click here

HINT:

Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.

PROCEDURE

1.	GO TO CAN COMMUNICATION SYSTEM

(a) Refer to the CAN Communication System.

Click here

END

VC Output Circuit

DESCRIPTION

The ECM constantly generates a 5 V power source voltage from the auxiliary battery voltage supplied to the +B, +B2 (BATT) terminals to operate the microprocessor. The ECM also provides this power to the sensors through the VC output circuit.

When the VC circuit has a short circuit, the microprocessor in the ECM and sensors that are supplied power through the VC circuit are deactivated because power is not supplied from the VC circuit. When the system is in this condition, it will not start.

WIRING DIAGRAM

For the circuit diagram of the ECM power source refer to the ECM power source circuit.
Click here
VC Output Circuit

CAUTION / NOTICE / HINT

NOTICE:

Check the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE

1.	CHECK CONNECTION BETWEEN TECHSTREAM AND ECM

(a) Connect the Techstream to the DLC3.

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

(d) Check the communication between the Techstream and ECM.

HINT:

It can be checked using the "Engine" item of the Data List.

Result	Proceed to
Communication is not possible	A
Communication is possible	B

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

2.	CHECK EFI NO. 1 FUSE VOLTAGE

*1	No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly
*2	EFI NO. 1 Fuse

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

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
1 (EFI NO. 1 fuse) - Body ground	Power switch on (IG)	11 to 14 V

HINT:

Check the fuse with it installed to the No. 1 engine room relay block and No. 1 junction block assembly.
If the result is not as specified, since current is not flowing to the +B and +B2 terminals of the ECM, the system may not be started.

GO TO ECM POWER SOURCE CIRCUIT

3.	CHECK CONNECTION BETWEEN TECHSTREAM AND ECM (THROTTLE POSITION SENSOR)

(a) Disconnect the throttle body with motor assembly connector.

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

(d) Check the communication between the Techstream and ECM.

HINT:

It can be checked using the "Engine" item of the Data List.

Result	Proceed to
Communication is not possible	A
Communication is possible	B

HINT:

Perform "Inspection After Repair" after replacing the throttle body with motor assembly.

Click here

REPLACE THROTTLE BODY WITH MOTOR ASSEMBLY

4.	CHECK CONNECTION BETWEEN TECHSTREAM AND ECM (CRANKSHAFT POSITION SENSOR)

(a) Disconnect the crankshaft position sensor connector.

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

(d) Check the communication between the Techstream and ECM.

HINT:

It can be checked using the "Engine" item of the Data List.

Result	Proceed to
Communication is not possible	A
Communication is possible	B

REPLACE CRANKSHAFT POSITION SENSOR

5.	CHECK CONNECTION BETWEEN TECHSTREAM AND ECM (CAMSHAFT POSITION SENSOR (FOR INTAKE CAMSHAFT))

(a) Disconnect the camshaft position sensor (for intake camshaft) connector.

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

(d) Check the communication between the Techstream and ECM.

HINT:

It can be checked using the "Engine" item of the Data List.

Result	Proceed to
Communication is not possible	A
Communication is possible	B

REPLACE CAMSHAFT POSITION SENSOR (FOR INTAKE CAMSHAFT)

6.	CHECK CONNECTION BETWEEN TECHSTREAM AND ECM (MANIFOLD ABSOLUTE PRESSURE SENSOR)

(a) Disconnect the manifold absolute pressure sensor connector.

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

(d) Check the communication between the Techstream and ECM.

HINT:

It can be checked using the "Engine" item of the Data List.

Result	Proceed to
Communication is not possible	A
Communication is possible	B

REPLACE MANIFOLD ABSOLUTE PRESSURE SENSOR

7.	CHECK CONNECTION BETWEEN TECHSTREAM AND ECM (CAMSHAFT POSITION SENSOR (FOR EXHAUST CAMSHAFT))

(a) Disconnect the camshaft position sensor (for exhaust camshaft) connector.

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

(d) Check the communication between the Techstream and ECM.

HINT:

It can be checked using the "Engine" item of the Data List.

Result	Proceed to
Communication is not possible	A
Communication is possible	B

REPLACE CAMSHAFT POSITION SENSOR (FOR EXHAUST CAMSHAFT)

8.	CHECK CONNECTION BETWEEN TECHSTREAM AND ECM (OIL PRESSURE SENSOR (OIL PRESSURE SENDER GAUGE ASSEMBLY))

(a) Disconnect the oil pressure sensor (oil pressure sender gauge assembly) connector.

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

(d) Check the communication between the Techstream and ECM.

HINT:

It can be checked using the "Engine" item of the Data List.

Result	Proceed to
Communication is not possible	A
Communication is possible	B

REPLACE OIL PRESSURE SENSOR (OIL PRESSURE SENDER GAUGE ASSEMBLY)

9.	CHECK CONNECTION BETWEEN TECHSTREAM AND ECM (FUEL PRESSURE SENSOR (FOR HIGH PRESSURE SIDE))

(a) Disconnect the fuel pressure sensor (for high pressure side) connector.

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

(d) Check the communication between the Techstream and ECM.

HINT:

It can be checked using the "Engine" item of the Data List.

Result	Proceed to
Communication is not possible	A
Communication is possible	B

HINT:

Perform "Inspection After Repair" after replacing the fuel pressure sensor (for high pressure side).

Click here

REPLACE FUEL PRESSURE SENSOR (FOR HIGH PRESSURE SIDE)

10.	CHECK CONNECTION BETWEEN TECHSTREAM AND ECM (FUEL PRESSURE SENSOR (FOR LOW PRESSURE SIDE))

(a) Disconnect the fuel pressure sensor (for low pressure side) connector.

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

(d) Check the communication between the Techstream and ECM.

HINT:

It can be checked using the "Engine" item of the Data List.

Result	Proceed to
Communication is not possible	A
Communication is possible	B

HINT:

Perform "Inspection After Repair" after replacing the fuel pressure sensor (for low pressure side).

Click here

REPLACE FUEL PRESSURE SENSOR (FOR LOW PRESSURE SIDE)

11.	CHECK CONNECTION BETWEEN TECHSTREAM AND ECM (MASS AIR FLOW METER SUB-ASSEMBLY)

(a) Disconnect the mass air flow meter sub-assembly connector.

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

(d) Check the communication between the Techstream and ECM.

HINT:

It can be checked using the "Engine" item of the Data List.

Result	Proceed to
Communication is not possible	A
Communication is possible	B

HINT:

Perform "Inspection After Repair" after replacing the mass air flow meter sub-assembly.

Click here

REPLACE MASS AIR FLOW METER SUB-ASSEMBLY

12.	CHECK CONNECTION BETWEEN TECHSTREAM AND ECM (CANISTER PUMP MODULE)

(a) Disconnect the canister pump module connector.

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

(d) Check the communication between the Techstream and ECM.

HINT:

It can be checked using the "Engine" item of the Data List.

Result	Proceed to
Communication is not possible	A
Communication is possible	B

REPLACE CANISTER PUMP MODULE

13.	CHECK CONNECTION BETWEEN TECHSTREAM AND ECM (FUEL TANK PRESSURE SENSOR)

(a) Disconnect the fuel tank pressure sensor connector.

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

(d) Check the communication between the Techstream and ECM.

HINT:

It can be checked using the "Engine" item of the Data List.

Result	Proceed to
Communication is not possible	A
Communication is possible	B

REPLACE FUEL TANK PRESSURE SENSOR

14.	CHECK HARNESS AND CONNECTOR

(a) Disconnect the throttle body with motor assembly connector.

(b) Disconnect the crankshaft position sensor connector.

(d) Disconnect the manifold absolute pressure sensor connector.

(e) Disconnect the camshaft position sensor (for exhaust camshaft) connector.

(f) Disconnect the oil pressure sensor (oil pressure sender gauge assembly) connector.

(g) Disconnect the fuel pressure sensor (for high pressure side) connector.

(h) Disconnect the fuel pressure sensor (for low pressure side) connector.

(i) Disconnect the mass air flow meter sub-assembly connector.

(j) Disconnect the canister pump module connector.

(k) Disconnect the fuel tank pressure sensor connector.

(l) Disconnect the ECM connectors.

(m) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
C55-109 (VCTA) - Body ground	Always	10 kΩ or higher
C55-116 (VCNE) - Body ground	Always	10 kΩ or higher
C55-88 (VCV1) - Body ground	Always	10 kΩ or higher
C55-113 (VCE1) - Body ground	Always	10 kΩ or higher
C55-121 (VCPM) - Body ground	Always	10 kΩ or higher
C55-99 (VCPE) - Body ground	Always	10 kΩ or higher
C55-78 (VCVG) - Body ground	Always	10 kΩ or higher
C55-98 (VCPR) - Body ground	Always	10 kΩ or higher
C55-84 (VCPF) - Body ground	Always	10 kΩ or higher
A19-48 (VCPP) - Body ground	Always	10 kΩ or higher
A19-57 (VPTK) - Body ground	Always	10 kΩ or higher

(n) Remove the VVT, EFI-MAIN NO. 2 and EFI-MAIN NO. 3 relays from the No. 1 engine room relay block and No. 1 junction block assembly.

HINT:

Remove the VVT, EFI-MAIN NO. 2 and EFI-MAIN NO. 3 relays connected between the checked terminals as the coil inside the relay influences the measurement value.

(o) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
A19-9 (+B) - 1 (EFI NO. 1 fuse)	Always	Below 1 Ω
A19-35 (+B2) - 1 (EFI NO. 1 fuse)	Always	Below 1 Ω
A19-9 (+B) - Body ground	Always	10 kΩ or higher
A19-35 (+B2) - Body ground	Always	10 kΩ or higher

REPLACE ECM

REPAIR OR REPLACE HARNESS OR CONNECTOR

Vehicle Control History

VEHICLE CONTROL HISTORY

VEHICLE CONTROL HISTORY (AIRBAG SYSTEM)

HINT:

A part of the control history can be confirmed using the vehicle control history.

Click here

VEHICLE CONTROL HISTORY (HYBRID CONTROL SYSTEM)

HINT:

A part of the control history can be confirmed using the vehicle control history.

Click here

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