Several control units are applied to electronically controlled vehicles. These units perform each control with informations from various sensors. Thus, sharing signal information from sensors is needed, so CAN communication type whose communication speed is high and insensitive to electrical noise by spark generation is adopted to controlling power-train(ECM, TCM,ESP ECM, ABS ECM)
As sharing signals of engine speed, APS, gear shifting, torque reduction in ESP and various modules, active control is performed.
DTC DESCRIPTION
Checking CAN communication, under detecting condition, if an error within the detecting condition is detected for more than 1.5 sec., PCM sets U0001. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.
DTC DETECTING CONDITION
Item
Detecting Condition
Possible cause
DTC Strategy
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Detects failures in communication between the PCM and another or modules in the vehicle which are on the CAN serial bus.
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CAN BUS
●
CAN communication module component
EnableConditions
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Engine Run Time ≥ 2sec.
●
Ignition Voltage ≥ 11V
Threshold value
●
CAN communicatin error
DiagnosisTime
●
Continuous
MIL On Condition
●
2 Driving Cycles
SIGNAL WAVEFROM AND DATA
SPECIFICATION
Format
DIGITAL "0"
DIGITAL "1"( BUS IDLE )
CAN Communication Line Resistance
HIGH
LOW
HIGH
LOW
PCM
I/P JUNCTION BOX
CAN 2.0B
3.5V
1.5V
2.5V
2.5V
120Ω (20℃)
120Ω (20℃)
SCHEMATIC DIAGRAM
MONITOR DTC STATUS
1.
Check DTC Status
(1)
Connect scantool to Data Link Connector(DLC).
(2)
IG "ON".
(3)
Select "Diagnostic Trouble Codes(DTCs)" mode, and then Press F4(DTAL) to check DTC's information from the DTCs menu
(4)
Read "DTC Status" parameter.
(5)
Is parameter displayed "Present fault"?
▶ Go to "Terminal and connector inspection" procedure.
▶ Fault is intermittent caused by poor contact in the sensor’s and/or PCM’s connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure
TERMINAL AND CONNECTOR INSPECTION
1.
Many malfunctions in the electrical system are caused by poor harness 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?
▶ Repair as necessary and go to "Verification of Vehicle Repair" procedure
▶ Go to "Signal Circuit Inspection" procedure.
SIGNAL CIRCUIT INSPECTION
1.
Check CAN BUS resistance in Data Link Connector
(1)
Ignition "OFF"
(2)
Measure the resistance between terminals 3 and 11 of data link connector (Test 1)
(3)
Disconnect PCM connector.
(4)
Measure the resistance between terminals 3 and 11 of data link connector (Test 2)
▶ Go to "2.Check short to ground in CAN BUS" as follows.
▶ Below 10Ω for both conditions(disconnected, connected) : Repair short between CAN BUS lines and go to "Verification of Vehicle Repair".
▶ 120Ω for both conditions(disconnected, connected) : Go to "4. Check CAN BUS continuity".
▶ Infinite Ω for both conditions(disconnected, connected) :Repair open in CAN communication circuit between DLC terminal and In-pannel junction box.
2.
Check short to ground in CAN BUS
(1)
Ignition "OFF"
(2)
Disconnect PCM and ESC connector.
(3)
Check continuity between DLC terminal 3 and chassis ground. (CAN HIGH line)
(4)
Check continuity between DLC terminal 11 and chassis ground. (CAN LOW line)
Specification : Discontinuity ( Infinite Ω )
(5)
Is measured resistance within the specification?
▶ Go to "3. Check short to battery in CAN BUS".
▶ Repair short to ground in circuit and go to "Verification of Vehicle Repair".
3.
Check short to battery in CAN BUS
(1)
Ignition "OFF"
(2)
Disconnect PCM and ESC connector.
(3)
Ignition "ON"
(4)
Measure the voltage of DLC terminal 3. (CAN HIGH line)
(5)
Measure the voltage of DLC terminal 11. (CAN LOW line)
Specification : 0.0V~0.1V
(6)
Is measured resistance within the specification with both connector disconnected?
▶ Go to"4. Check CAN BUS continuity" as follows.
▶ Repair short to battery and go to "Verification of Vehicle Repair".
4.
Check CAN BUS continuity
(1)
Ignition "OFF"
(2)
Disconnect PCM and ESC connector.
(3)
Check continuity in CAN HIGH line.
( CAN HIGH : PCM connector terminal 41, and Passenger compartment junction block terminal 15, Data link connector(DLC) terminal 3 )
(4)
Check continuity CAN LOW line.
( CAN LOW : PCM connector terminal 42, and Passenger compartment junction block terminal 16, Data link connector(DLC) terminal 11 )
Specification : Continuity(below 1.0Ω )
(5)
Is the measured resistance within the specification?
▶ Go to "Component Inspection".
▶ Repair open in CAN BUS line and go to "Verification of Vehicle Repair".
COMPONENT INSPECTION
1.
Check CAN communication waveform generation
(1)
Ignition "OFF"
(2)
Connect 2 channel scope to DLC terminal 3(CAN HIGH) and 11(CAN LOW).
(3)
Ignition "ON" after connecting only PCM to CAN BUS.
(4)
Ignition "ON" after connecting only ABS or ESP module to CAN BUS.
Specification : At Ignition "ON", the waveform same as "Signal Waveform ＆ Data" of above signal waveform.
※ Different from "Signal Waveform ＆ Data", if 1) both CAN HIGH and LOW signal are fixed at 2.5 V or
2) HIGH and LOW signal are fixed at 3.5 V and 1.5 V, respectively, it is due to communication error between modules.
(5)
Does correct waveform generate from each module?
▶ Go to "Verification of Vehicle Repair".
▶ Replace the module which generates poor communication waveform, and go to "Verification of Vehicle Repair".
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"?
▶ System performing to specification at this time. Clear the DTC.
