U0101
DTC U0101 SERIAL COMMUNICATION PROBLEM WITH TCU (TIME-OUT)GENERAL DESCRIPTION
A communication line exists between the Engine Control Module(ECM) and the Transaxle Control Module(TCM). The communication is through a Control Area Network(CAN). Without CAN communication, an independent pin and wiring is needed to receive a sensor information from a ECM. The more information to be communicated, the more wirings is required. In case of CAN communication type, all the information need to be communicated among control modules such as ECM and TCM use CAN lines.
DTC DESCRIPTION
The ECM sets DTC U0101 if ECM detects that communication time via CAN exceeds threshold value.
DTC Detecting Condition:
Signal Waveform:
MONITOR DTC STATUS
1. Connect scan tool and select "Diagnostic Trouble Cod es(DTCs)" mode.
2. Press F4(DTAL) to select DTC information from the DTCs menu.
3. Confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions.
4. Read "DTC Status" parameter.
5. Is parameter displayed "History(Not Present) fault"?
NOTE:
- History (Not Present) fault: DTC occurred but has been cleared.
- Present fault: DTC is occurring at present time.
YES: Fault is intermittent caused by poor contact in the sensor(s) and/or the ECM's connector was repaired and ECM memory was not cleared. Thoroughly check connectors for loose or poor connections, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure
NO: Go to next step as below.
TERMINAL AND CONNECTOR INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness(es) and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?
YES: Repair as necessary and go to "Verification of Vehicle Repair" procedure
NO: Go to "CAN High line Inspection" procedure.
CAN HIGH LINE INSPECTION
1. Check for Open in harness
1. Ignition "OFF".
2. Disconnect ECM and TCM connectors.
3. Measure resistance between terminals 36 of the ECM harness connector and 3 of the TCM harness connector.
Specification: Approx. 0 Ohm
4. Is resistance within the specification?
YES: Go to next step as below.
NO: Repair as necessary and go to "Verification of Vehicle Repair" procedure.
2. Check for short to ground in harness.
1. Measure resistance between terminal 36 of the ECM harness connector and chassis ground.
Specification: Infinite
2. Is resistance within the specification?
YES: Go to next step as below
NO: Repair as necessary and go to "Verification of Vehicle Repair" procedure.
3. Check for short to battery in harness.
1. Reconnect the ECM connector.
2. Ignition "ON" & Engine "OFF".
3. Measure voltage between terminal 36 of the ECM harness connector and chassis ground.
Specification: Approx. 0V
4. Is voltage within the specification?
YES: Go to "CAN Low Line Inspection" procedure
NO: Repair as necessary and go to "Verification of Vehicle Repair" procedure.
CAN LOW LINE INSPECTION
1. Check for Open in harness.
1. Ignition "OFF"
2. Disconnect ECM and TCM connectors.
3. Measure resistance between terminals 37 of the ECM harness connector and 4 of the TCM harness connector.
Specification: Approx. 0 Ohm
4. Is resistance within the specification?
YES: Go to next step as below.
NO: Repair as necessary and go to "Verification of Vehicle Repair" procedure.
2. Check for short to ground in harness.
1. Measure resistance between terminal; 37 of the ECM harness connector and chassis ground.
Specification: Infinite
2. Is resistance within the specification?
YES: Go to next step as below
NO: Repair as necessary and go to "Verification of Vehicle Repair" procedure.
3. Check for short to battery in harness.
1. Reconnect the ECM connector.
2. Ignition "ON" & Engine "OFF".
3. Measure voltage between terminal 37 of the ECM harness connector and chassis ground.
Specification: Approx. 0V
4. Is voltage within the specification?
YES: Check for poor connection between ECM and component: backed out terminal, improper mating, broken locks or poor terminal to wire connection. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
NO: Repair as necessary and go to "Verification of Vehicle Repair" procedure.
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode.
2. Press F4(DTAL) and confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions.
3. Read "DTC Status" parameter.
4. Is parameter displayed "History(Not Present) fault"?
YES: System performing to specification at this time. Clear the DTC.
NO: Go to the applicable troubleshooting procedure.