5A
DTC P1774 (No.76): Control Module Communication Bus Off (M13A Model with VVT)
Wiring Diagram
1. ECM [A]: Terminal arrangement of TCM connector (M13 engine model with VVT) (viewed from harness side)
2. TCM [B]: Terminal arrangement of ECM connector (M13 engine model without VVT) (viewed from harness side)
DTC Detecting Condition and Trouble Area
DTC detecting condition Trouble area
Transmission error that is inconsistent between transmission data and transmission monitor (CAN bus monitor) data is detected more than 7 times continuously.
• ECM
• TCM
• CAN circuit
DTC Confirmation Procedure
1) Connect scan tool to DLC with ignition switch OFF.
2) Clear DTCs in TCM and ECM memories.
3) Start engine and run it for 1 min. or more.
4) Check DTC.
Troubleshooting
Step Action YES NO
1
Was A/T System Check performed?
Go to Step 2.
Go to A/T System Check .
2
Check DTC
1) Connect scan tool to DLC with ignition switch turned OFF.
2) Check DTC for ECM and TCM.
Is there any DTC(s) (other than DTC P1674, P1675, P1676 for ECM and DTC P1774, P1775, P1777 for TCM)?
Go to applicable DTC diag. flow.
Go to Step 3.
3
Check ECM and TCM connectors
1) Check for proper connection at each ECM and TCM connector terminals with ignition switch turned OFF.
2) If connections are OK, recheck DTC for ECM with engine running.
Is there DTC P1774?
Go to Step 4.
Intermittent trouble. Check for intermittent referring to Intermittent and Poor Connection Inspection .
4
Check TCM Power and Ground Circuit
1) Check for TCM power and ground circuit referring to TCM Power and Ground Circuit Check .
Is it in good condition?
Go to Step 5.
Repair TCM power and/or ground circuits.
5
Check DTC for TCM (bus off)
1) Disconnect connectors from ECM with ignition switch turned OFF.
2) Check DTC(s) for TCM.
Is there DTC P1774?
Go to Step 6.
Substitute a known-good ECM and recheck.
6
Check CAN Communication Line Circuit Insulation
1) Disconnect connectors from ECM and TCM with ignition switch OFF.
2) Measure resistance between “E121-7” and “E121-17” terminals of TCM connector.
Is resistance infinity?
Go to Step 7.
Repair insulation of CAN communication line circuit referring to Precaution for CAN Communication System .
7
Check CAN Communication Line Circuit Continuity
1) Measure resistance at the following connector terminals.
• Between “E121-7” terminal of TCM connector and “E118-7” terminal of ECM connector
• Between “E121-17” terminal of TCM connector and “E118-8” terminal of ECM connector
Is each resistance below 1 Ω?
Go to Step 8.
Repair open or high resistance of CAN communication line circuit referring to Precaution for CAN Communication System .
8
Check CAN Communication Line Circuit Ground Short
1) Measure resistance at the following connector terminals.
• Between “E121-7” terminal of TCM connector and vehicle body ground
• Between “E121-17” terminal of TCM connector and vehicle body ground
Is each resistance infinity?
Go to Step 9.
Repair shorted to ground of CAN communication line circuit referring to Precaution for CAN Communication System .
9
Check CAN Communication Line Circuit Power Supply Short
1) Measure voltage at the following connector terminals with ignition switch turned ON.
• Between “E121-7” terminal of TCM connector and vehicle body ground
• Between “E121-17” terminal of TCM connector and vehicle body ground
Is each voltage 0 – 1 V?
Substitute a known-good TCM and recheck.
Repair shorted to power supply of CAN communication line circuit referring to Precaution for CAN Communication System .