Lexus ES: Control Module Communication Bus Off (U0073,U0100,U0126,U0129)
DESCRIPTION
The 4WD ECU assembly inputs the signals sent from the ECM, skid control ECU (brake actuator assembly) and steering sensor via CAN communication.
When DTCs indicating a CAN communication system malfunction are output, repair the CAN communication system before repairing each corresponding sensor.
| DTC No. | Detection Item | DTC Detection Condition | Trouble Area |
| U0073 | Control Module Communication Bus Off | -
When the following continues for 5 seconds or more:
-
Signals from the 4WD ECU assembly are not received.
-
When the following occurs 10 times consecutively:
-
A communication malfunction (bus off) occurs one or more times within 0.1 seconds.
| -
CAN communication system
-
4WD ECU assembly
|
| U0100 | Lost Communication with ECM / PCM "A" | -
When both of the following continue for 2 seconds or more:
-
The voltage of the IG1 terminal is 10 V or more.
-
At a vehicle speed of 60 km/h (38 mph) or more, communication with the ECM cannot be performed.
| -
CAN communication system
-
4WD ECU assembly
-
ECM
|
| U0126 | Lost Communication with Steering Angle Sensor Module | -
When both of the following continue for 1 second or more:
-
The voltage of the IG1 terminal is 10 V or more.
-
Communication with the steering sensor cannot be performed.
-
When all of the following occur 10 times or more within 60 seconds:
-
The voltage of the IG1 terminal is 10 V or more.
-
The condition that communication with the steering sensor cannot be performed occurs once within 5 seconds.
| -
CAN communication system
-
4WD ECU assembly
-
Steering sensor
|
| U0129 | Lost Communication with Brake System Control Module | -
When both of the following continue for 3 seconds or more:
-
The voltage of the IG1 terminal is 10 V or more.
-
Communication with the skid control ECU (brake actuator assembly) cannot be performed.
| -
CAN communication system
-
4WD ECU assembly
-
Skid control ECU (brake actuator assembly)
|
DTC Detection Conditions: U0073
| | Vehicle Condition |
| Pattern 1 | Pattern 2 |
| Diagnosis Condition | One or more times within 0.1 seconds. | - | ○ |
| Malfunction Status | Signals from the 4WD ECU assembly are not received. | ○ | - |
| A communication malfunction (bus off) occurs. | - | ○ |
| Detection Time | 5 seconds or more | 10 times consecutively |
| Number of Trips | 1 trip | 1 trip |
DTC Detection Conditions: U0126
| | Vehicle Condition |
| Pattern 1 | Pattern 2 |
| Diagnosis Condition | The voltage of the IG1 terminal is 10 V or more. | ○ | ○ |
| Malfunction Status | Communication with the steering sensor cannot be performed. | ○ | - |
| The condition that communication with the steering sensor cannot be performed occurs once within 5 seconds. | - | ○ |
| Detection Time | 1 second or more | 10 times or more within 60 seconds |
| Number of Trips | 1 trip | 1 trip |
PROCEDURE
(a) Check for DTCs.
Chassis > Four Wheel Drive > Trouble Codes
(b) Record the output DTCs (dynamic torque control AWD system).
HINT:
When DTCs indicating a CAN communication system malfunction are output, repair the CAN communication system before repairing each corresponding sensor.
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