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









INSPECTION PROCEDURE

PROCEDURE

1. CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC U0101)
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine / Trouble Code.
(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 engine switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:





(d) Turn the engine switch off.
(e) Measure the resistance according to the value(s) in the table below.
Standard resistance (check foe open):





(f) Reconnect the TCM connector.
NG -- GO TO TCM POWER SOURCE CIRCUIT
OK -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR




(a) Disconnect the B40 TCM connector.
(b) Disconnect the B12 ECM connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:





(d) Reconnect the TCM connector.
(e) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
4. REPLACE ECM
(a) Replace the ECM Removal.
NOTE:
Replace the ECM with an ECM from a normally functioning vehicle of the same model.

NEXT -- Continue to next step.
5. CHECK IF DTC RECURS
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the Techstream on.
(d) Clear the DTC.
(e) Start the engine.
(f) Enter the following menus: Powertrain / Engine / Trouble Code.
(g) Read the DTCs.
Result:






B -- REPLACE ECM
A -- REPLACE TCM