DTC    U0100    Lost Communication with ECM / PCM "A"

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DESCRIPTION


DTC No.
DTC Detection Condition
Trouble Area
U0100
No communication from ECM
  1. Power source circuit of ECM
  2. ECM main wire or connector
  3. ECM

WIRING DIAGRAM


E176027E03


INSPECTION PROCEDURE

NOTICE:
  1. Inspect the fuses for circuit related to this system before performing the following inspection procedure.
  2. Turn the ignition switch off before measuring the resistances of the CAN main wire and the CAN branch wire.
  3. After the ignition switch is turned off, check that the key reminder warning system and light reminder warning system are not in operation.
  4. Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the ignition switch, any other switches or the doors. If doors need to be opened in order to check connectors, open the doors and leave them open.

HINT:
Operating the ignition switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.

1.CHECK FOR OPEN IN CAN BUS WIRE (ECM MAIN WIRE)

  1. Turn the ignition switch off.



    E175986E02

  1. Disconnect the A18 ECM connector.

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    A18-4 (CAN+) - A18-5 (CAN-)
    		Ignition switch off
    		108 to 132 Ω

    Text in Illustration 
    *1
    		Front view of wire harness connector
    (to ECM)

  1. Reconnect the ECM connector.



NG
REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (CAN-H, CAN-L)
OK


2.CHECK HARNESS AND CONNECTOR (ECM - BATTERY AND BODY GROUND)


    E175987E01

  1. Disconnect the A18 and B8 ECM connectors.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    B8-105 (E1) - Body ground
    		Always
    		Below 1 Ω

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

    Standard Voltage:
    Tester Connection
    		Switch Condition
    		Specified Condition
    A18-27 (IGSW) - Body ground
    		Ignition switch ON
    		11 to 14 V
    A18-2 (+B) - Body ground
    		Ignition switch ON
    		11 to 14 V
    A18-1 (+B2) - Body ground
    		Ignition switch ON
    		11 to 14 V

    Text in Illustration 
    *1
    		Front view of wire harness connector
    (to ECM)

Result 
Result
Proceed to
NG
A
OK (for 1KR-FE engine)
B
OK (for 1NR-FE engine)
C

  1. Reconnect the ECM connectors.



B
REPLACE ECM (Click here)

C
REPLACE ECM (Click here)
A

REPAIR OR REPLACE HARNESS OR CONNECTOR