Engine Control - SFI System

1AR-FE ENGINE CONTROL: SFI SYSTEM: U0101: Lost Communication with TCM

DTC U0101 - Lost Communication with TCM

DESCRIPTION

The Transmission Control Module (TCM) and ECM perform 2-way communication with each other via the Controller Area Network (CAN). The TCM sends signals to the ECM concerning required engine speed, required engine torque, warning indicators in the combination meter, DTCs and other data. The ECM sends signals to the TCM concerning engine speed, opening angle of the throttle valve, temperature of intake air, temperature of engine coolant, engine torque 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





CONFIRMATION DRIVING PATTERN





1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON and turn the Techstream on.
3. Clear the DTCs (even if no DTCs are stored, perform the Clear DTC procedure) DTC Check / Clear.
4. Turn the ignition switch off.
5. Turn the ignition switch to ON and turn the Techstream on [A].
6. Wait 5 seconds or more.
7. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
8. Input the DTC: U0101.
9. Check the DTC judgment result [B].





HINT: If the judgment result shows ABNORMAL, the system has a malfunction.

10. If the test result is UNKNOWN, enter the following menus: Powertrain / Engine / Trouble Codes / Pending.
11. Read Pending DTCs.
HINT: If a pending DTC is output, the system is malfunctioning.

12. If the test result is INCOMPLETE or UNKNOWN and no pending DTC is output, perform a universal trip and check for permanent DTCs DTC Check / Clear.
HINT:
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.

WIRING DIAGRAM





INSPECTION PROCEDURE
NOTICE: Inspect the fuses for circuits related to this system before performing the following inspection procedure.
HINT: Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.

PROCEDURE

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





HINT: If any DTCs other than U0101 are output, troubleshoot those DTCs first.

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

2. INSPECT ECU POWER SOURCE CIRCUIT (TCM POWER SOURCE)




(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:





Text in Illustration





(d) Reconnect the TCM connector.

NG -- GO TO TCM POWER SOURCE CIRCUIT
OK -- Continue to next step.

3. CHECK HARNESS AND CONNECTOR (ECM - TCM)
(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 (Check for Open):





Standard Resistance (Check for Short):





Text in Illustration





(d) Reconnect the ECM connector.
(e) Reconnect the TCM connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - TCM)
OK -- Continue to next step.

4. REPLACE ECM
(a) Replace the ECM Removal.
NEXT -- Continue to next step.

5. CHECK WHETHER DTC OUTPUT RECURS (DTC U0101)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine / Trouble Codes.
(e) Read the DTCs.
Result:





B -- REPLACE TCM
A -- REPAIR COMPLETED