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 CAN Communication 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
A -- Continue to next step.
2. INSPECT TCM (POWER SOURCE, BODY GROUND)





(a) Disconnect the A12 and E5 TCM connectors.
(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 -- REPAIR OR REPLACE HARNESS OR CONNECTOR (TCM - BATTERY, BODY GROUND)
OK -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (ECM - TCM)





(a) Disconnect the A13 ECM connector.
(b) Disconnect the A12 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