DTC    U0100    Lost Communication with ECM / PCM "A"

DTC    U0121    Lost Communication with Anti-lock Brake System (ABS) Control Module

DTC    U0131    Lost Communication with Electric Power Steering ECU

DTC    U0140    Lost Communication with Main Body ECU

DTC    U0151    Lost Communication with Airbag ECU

DTC    U0155    Lost Communication with Instrument Panel Cluster Control Module (Combination Meter)

DTC    U0164    Lost Communication with HVAC Control Module


DESCRIPTION

The engine stop and start ECU communicates with the SFI system, ABS/VSC system, EPS, combination meter system, and air conditioning system via CAN. If any of these CAN communication malfunctions occurs, the respective DTC will be stored.

HINT:
If the backup boost converter detects overcurrent in a power source circuit, power supply to the circuit is shut off. Therefore a DTC indicating a CAN communication error with the applicable system will be stored in addition to DTC P323B.

Example: If the backup boost converter detects overcurrent in the power source circuit for EPS and the power supply is shut off, DTC U0131 and P323B (Backup Boost Converter) will be stored.
The Controller Area Network (CAN) is a serial data communication system for real time applications. This is a vehicle multiplex communication system which has a high communication speed (500 kbps) and a high level of ability to detect malfunctions. By pairing CANH and CANL bus wires, CAN communication is performed using the voltage differential between the wires.

HINT:
  1. Malfunctions in the CAN bus wires can be confirmed using the DLC3. However, if there is an open in the branch wire to the DLC3, malfunctions in the CAN bus wires cannot be detected.
  2. Using the intelligent tester makes it possible to check for CAN communication system DTCs.


DTC No.
DTC Detection Condition
Trouble Area
U0100
No communication between the engine stop and start ECU and the ECM for 0.76 seconds.
  1. Harness or connector
  2. Engine stop and start ECU
  3. ECM
U0121
No communication between the engine stop and start ECU and the skid control ECU for 2.4 seconds.
  1. Harness or connector
  2. Engine stop and start ECU
  3. Skid control ECU (brake actuator assembly)
U0131
No communication between the engine stop and start ECU and the power steering ECU for 0.8 seconds.
  1. Harness or connector
  2. Engine stop and start ECU
  3. Power steering ECU
U0140
No communication between the engine stop and start ECU and the main body ECU for 3.6 seconds.
  1. Harness or connector
  2. Engine stop and start ECU
  3. Main body ECU
U0151
No communication between the engine stop and start ECU and the center airbag sensor for 10.6 seconds.
  1. Harness or connector
  2. Engine stop and start ECU
  3. Center airbag sensor
U0155
No communication between the engine stop and start ECU and the combination meter for 10.6 seconds.
  1. Harness or connector
  2. Engine stop and start ECU
  3. Combination meter
U0164
No communication between the engine stop and start ECU and the A/C amplifier for 10.6 seconds.
  1. Harness or connector
  2. Engine stop and start ECU
  3. A/C amplifier

INSPECTION PROCEDURE

Proceed to CAN Communication System (Click here).

HINT:
When any DTCs indicating a CAN communication system malfunction are output, troubleshoot the CAN communication system before repairing each corresponding component.