Automatic Transaxle System

U760E AUTOMATIC TRANSAXLE: AUTOMATIC TRANSAXLE SYSTEM: U0100: Lost Communication with ECM / PCM "A"
U0100 - Lost Communication with ECM / PCM "A"

DESCRIPTION

The engine control unit communicates with the TCM using the Controller Area Network (CAN).

If there is a problem in this communication, the TCM sets a DTC.





MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS





TYPICAL MALFUNCTION THRESHOLDS





WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
Perform the universal trip to clear permanent DTCs Reading and Clearing Diagnostic Trouble Codes.

HINT
* Refer to inspection procedure for CAN communication system.
* If the CAN communication malfunctions, the TCM cannot receive the current data from the ECM. In this case, the freeze frame data output from the TCM has not been updated, so the data will not be useful for the inspection. However, reading the Data List as the first step in troubleshooting is effective to find malfunctions.
* The malfunction area can be checked using the Bus Check function on the Techstream Diagnosis System.

PROCEDURE

1. CHECK ECU TERMINAL VOLTAGE (+B AND E1 TERMINALS)

(a) Disconnect the TCM connector.





(b) Turn the ignition switch to ON.

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

Standard Voltage:





(d) Turn the ignition switch off.

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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

2. CHECK HARNESS AND CONNECTOR (TCM - ECM)

(a) Disconnect the TCM connector.





(b) Disconnect the ECM connector.

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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

3. CHECK IF DTC OUTPUT RECURS

(a) Connect the Techstream to the DLC3.

(b) Clear the DTCs.

(c) Replace the TCM.

HINT
Replace the TCM with a TCM from a normally functioning vehicle of the same model.

(d) Start the engine.

(e) Read the DTCs.

Result:





B -- REPLACE TCM Removal

A -- REPLACE ECM Removal