U0101

2GR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: U0101: Lost Communication with TCM

DTC U0101 - Lost Communication with TCM

DESCRIPTION

The Transmission Control Module (TCM) and ECM perform 2-way communications with each other via the Controller Area Network (CAN). The TCM sends signals to the ECM concerning required engine rpm, required engine torques, warning indicators in the combination meter, DTCs and other data. The ECM sends signals to the TCM concerning engine rpm, opening angles of the throttle valve, temperature of intake air, temperature of engine coolant, engine torques and other data. If the TCM cannot communicate with the ECM, the TCM will conclude that there is a malfunction in the CAN system, illuminate the MIL and set a DTC.





MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS





TYPICAL MALFUNCTION THRESHOLDS





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC U0101)
(a) Connect Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the tester on.
(d) Enter the following menus: Powertrain / Engine / Trouble Codes.
(e) Read the DTCs.
Result:





B -- GO TO DTC CHART
A -- Continue to next step.

2. CHECK TCM TERMINAL VOLTAGE (+B AND E1 TERMINALS)





(a) Disconnect the TCM connector.
(b) Turn the ignition switch to ON.
(c) Measure the voltage of the TCM connectors.
Standard voltage:





(d) Turn the ignition switch off.
(e) Measure the resistance of the TCM connector.
Standard resistance:






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

3. CHECK HARNESS AND CONNECTOR





(a) Disconnect the TCM connector.
(b) Disconnect the ECM connector.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:






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

4. REPLACE ECM
(a) Replace the ECM Components.

NOTE: Replace the ECM with a ECM from a normally functioning vehicle of the same model.

NEXT -- Continue to next step.

5. CHECK IF DTC RECURS
(a) Connect Techstream to the DLC3.
(b) Clear the DTCs.
(c) Start the engine.
(d) Read the DTCs.
Result:





B -- REPLACE ECM
A -- REPLACE TCM