AA80E Automatic Transmission

AA80E AUTOMATIC TRANSMISSION: AUTOMATIC TRANSMISSION SYSTEM: U0100: Lost Communication with ECM / PCM "A"

DTC U0100 - Lost Communication with ECM / PCM "A"

DESCRIPTION

The ECM communicates with the TCM using the Controller Area Network (CAN).
If there is a problem in this communication, the TCM sets the DTC.






MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS





TYPICAL MALFUNCTION THRESHOLDS





WIRING DIAGRAM





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

PROCEDURE

1. CHECK DTC OUTPUT (IN ADDITION TO DTC U0100)
(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 / ECT / Trouble Codes.
(e) Read the DTCs using the Techstream.
Result:





HINT:
If any other codes besides U0100 are output, perform troubleshooting for those DTCs first.

B -- Go to DTC Chart Diagnostic Trouble Code Descriptions
A -- Continue to next step.
2. INSPECT TCM (POWER SOURCE, BODY GROUND)





(a) Disconnect the TCM connector.
(b) Turn the engine switch on (IG).
(c) Measure the voltage of the wire harness side connectors.
Standard voltage:





(d) Turn the engine switch off.
(e) Measure the resistance of the wire harness side connectors.
Standard resistance:






NG -- CHECK TCM POWER SOURCE CIRCUIT
OK -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (ECM - TCM)





(a) Disconnect the ECM connector.
(b) Disconnect the TCM 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. CHECK IF DTC RECURS
(a) Clear the DTCs DTC Check / Clear.
(b) Replace the TCM Removal.
HINT:
Replace the TCM with a TCM of a normally functioning vehicle of the same model.
(c) Start the engine.
(d) Read the DTCs.
Result:






B -- REPLACE ECM
A -- Continue to next step.
5. REPLACE TCM
(a) Replace the TCM Removal.
NEXT -- PERFORM A/T CODE REGISTRATION