Fuel System

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 ABS control module use CAN lines.

DTC Description

The ECM determines CAN communication error and sets DTC U0001 if communication with other control devices (e.g. ABS) via CAN is impossible or ECM detects that communication time via CAN exceeds threshold value.

DTC Detecting Condition






Diagnostic Circuit Diagram






Signal Waveform & Data






Fig.1) Normal waveform with ignition ON

Monitor DTC Status

1. Connect GDS and select "DTC Analysis" mode
2. Click "DTC Status" on the menu bar to see DTC's information.
3. Confirm that "DTC Readiness Flag" indicates "COMPLETED". 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.






Check CAN communication line for open

1. Ignition "OFF"
2. Disconnect ECM harness connector.
3. Measure resistance between High signal terminal and Low signal terminal of ECM harness connector.

Specification :Approx. 110 - 130Ohms

4. Is resistance within the specification?






Check CAN communication line for short to ground

1. Measure resistance between High signal terminal of ECM harness connector and chassis ground.
2. Measure resistance between Low signal terminal of ECM harness connector and chassis ground.

Specification :Infinite(above 10kOhms)

3. Is resistance within the specification?






Check CAN communication line for short to battery

1. Disconnect the connectors related to the CAN communication
2. Ignition "ON" & Engine "OFF"
3. Measure voltage between High signal terminal of ECM harness connector and chassis ground.
4. Measure voltage between Low signal terminal of ECM harness connector and chassis ground.

Specification :Approx. 0V

5. Is voltage within the specification?






Terminal and connection 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?






Component Inspection

1. Ignition "OFF"
2. Measure resistance between High signal terminal and Low signal terminal of ECM connector(ECM side).

Specification :Approx. 110 - 130Ohms

3. Is resistance within the specification?






Verification of Vehicle Repair

After a repair, it is essential to verify that the fault has been corrected.
1. Connect GDS and select "DTC Analysis" mode.
2. Click "DTC Status" 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"?