C1616

C1616

Component Location:

General Description
The HECU sends requirement data, such as Torque reduction, the number of fuel cut cylinders, and TCS control requests, to the Engine PCM (ECM & TCM) through CAN bus line.
The Engine PCM (ECM) performs fuel cut functions according to requests from the HECU and retards ignition timing by torque reduction requests.
The PCM (TCM) maintains current gear positions during TCS control time, in order not to increase power which causes a Kickdown shift.

DTC Description
The HECU checks the CAN communication lines for normal TCS control, and sets this code if CAN BUS OFF status is detected for more than 100 ms.

DTC Detecting Condition:

Schematic Diagram:

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
a. Repair as necessary and then go to "Verification of Vehicle Repair" procedure.

NO
a. Go to "Signal Circuit Inspection" procedure.

Signal Circuit Inspection
1. Ignition "OFF".
2. Measure resistance between terminal "10" of the HECU harness connector and terminal "11" of the HECU harness connector.

a. Specification : Approx. 60 ohms






3. Is the measured resistance within specifications?

YES
a. Fault is intermittent caused by open or short in CAN signal harness or was repaired and HECU memory was not cleared. Go to "CAN Bus Short (to ground) Inspection" procedure.

NO
a. Check for open or short in CAN signal harness between terminal "10" of the HECU harness connector and terminal "11" of the HECU harness connector. Repair as necessary and then go to "Verification of vehicle Repair" procedure.

CAN Bus Short (to ground) Inspection
4. Ignition "OFF".
5. Disconnect the HECU harness connector.
6. Measure resistance between terminal "11,15" of the HECU harness connector and chassis ground.

a. Specification : Approx. Infinite ohms






7. Is the measured resistance within specifications?

YES
a. Go to "CAN Bus Short (between HIGH and LOW) Inspection" procedure.

NO
a. Check for short to ground in CAN HIGH signal harness in case of abnormal resistance measured between terminal "11" of the HECU harness connector and chassis ground. Repair as necessary and then go to "Verification of vehicle Repair" procedure.
b. Check for short to ground in CAN LOW signal harness in case of abnormal resistance measured between terminal "10" of the HECU harness connector and chassis ground. Repair as necessary and then go to "Verification of vehicle Repair" procedure.

CAN Bus Short (between HIGH and LOW) Inspection
8. Ignition "OFF".
9. Disconnect all the connector related to CAN such as HECU, ECM, EPS, ECS harness connector.
10. Measure resistance between terminal "10,11" of the HECU harness.

a. Specification : Approx. Infinite ohms







11. Is the measured resistance within specifications?

YES
a. Go to "Component Inspection" procedure.

NO
a. Check for short in CAN signal harness between terminal "10" of the HECU harness connector and terminal "11" of the HECU harness connector. Repair as necessary and then go to "Verification of vehicle Repair" procedure.

Component Inspection
1. Ignition "OFF".
2. Ignition "ON".
3. Connect scantool and select "Diagnostic Trouble Codes (DTCs)" mode
4. Using a scantool, Clear DTC.
5. Select "Diagnostic Trouble Codes (DTCs)" mode again.
6. Are any DTCs present?

YES
a. Substitute with a known-good HECU and check for proper operation. If problem is corrected, replace HECU and then go to "Verification of Vehicle Repair" procedure.

NO
a. Fault is intermittent caused by faulty HECU or was repaired and HECU memory was not cleared. 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 scantool and select "Diagnostic Trouble Codes (DTCs)" mode
2. Using a Scantool, Clear DTC.
3. Operate the vehicle within DTC Detecting Condition in General Information.
4. Are any DTCs present?

YES
a. Go to the applicable troubleshooting procedure.

NO
a. System performing to specification at this time.