ON-BOARD DIAGNOSTIC FUNCTION [CAN SYSTEM]
id0940001017a0
Failure detection function
• The failure detection function in each CAN system-related module detects malfunctions in input/output signals.
• This function outputs the DTC for the detected malfunction to the DLC-2, and also sends the detected result to the memory function and fail-safe function.
Fail-Safe Function
• When the failure detection function determines that there is a malfunction, the fail-safe function illuminates a warning light to advise the driver of the malfunction.
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Module
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Fail-safe function
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PCM
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• MIL illuminated
|
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• ABS (ABS/TCS) HU/CM
(with ABS (ABS/TCS))
• DSC HU/CM (with DSC)
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• ABS (ABS/TCS) suspended (with ABS (ABS/TCS))
• DSC suspended (with DSC)
• ABS warning light illuminated
• DSC/TCS indicator light illuminated
• DSC OFF light illuminated
• TCS OFF light illuminated
|
|
Instrument cluster
|
• Speedometer, tachometer, water temperature gauge: 0 displayed
• MIL illuminated
• ABS warning light illuminated
|
Memory Function
• The memory function stores the DTC for the malfunction of input/output signals for related parts, as determined by the failure detection function.
Self-Malfunction Diagnostic Function
• The self-malfunction diagnostic function determines that there is a malfunction, and outputs a signal, as a DTC, to the DLC-2. The DTC can be read out using an SST (WDS or equivalent).
DTC table
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DTC
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Malfunction location
|
DTC output module
|
|
U0073
|
CAN system communication error
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PCM
|
|
U0121
|
Communication error to ABS (ABS/TCS) HU/CM or DSC HU/CM
|
|
U0155
|
Communication error to instrument cluster
|
|
U1900
|
CAN system communication error
|
• ABS (ABS/TCS) HU/CM
(vehicles with ABS (ABS/TCS))
• DSC HU/CM (vehicles with DSC)
• Instrument cluster
|
|
U2516
|
CAN system wiring harness open and short circuit
|
PID/Data Monitoring Function
• The PID/data monitoring function is used to freely select and read out, in real time, the monitored items for the input/output signals of the ABS (ABS/TCS) HU/CM and instrument cluster.
• An SST (WDS or equivalent) is used to read out the PID/data monitor information.
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PID name (definition)
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Condition
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Specification
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Related module
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Terminal
|
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IC_MSG
(Missing message from the instrument cluster)
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Present
|
Circuit in the Instrument cluster is normal
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ABS (ABS/TCS) HU/CM or DSC HU/CM
|
• ABS (ABS/TCS) HU/CM: O, R
• DSC HU/CM: AF, AG
• Instrument cluster: 2W, 2X
|
|
Not Present
|
Circuit in the Instrument cluster is abnormal
|
|
ABS_MSG
(Missing message from the ABS (ABS/TCS) HU/CM or DSC HU/CM)
|
Present
|
Circuit in the ABS (ABS/TCS) HU/CM or DSC HU/CM is normal
|
Instrument cluster
|
|
Not Present
|
Circuit in the ABS (ABS/TCS) HU/CM or DSC HU/CM is abnormal
|
|
PCM_MSG
(Missing message from the PCM)
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Present
|
Circuit in the PCM is normal
|
• ABS (ABS/TCS) HU/CM or DSC HU/CM
• Instrument cluster
|
|
Not Present
|
Circuit in the PCM is abnormal
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Narrowing Down Malfunction Locations
• The on-board diagnostic function, by verifying the detected DTC and PID/data monitor information from each module, can narrow down a CAN system malfunction location. Refer to the Self-Malfunction Diagnostic Function and PID/Data Monitoring Function for detailed information regarding DTCs and the PID/data monitor. (See Self-Malfunction Diagnostic Function.) (See PID/Data Monitoring Function.)
Flowchart
Example (Open circuit in PCM-related wiring harness)
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Note
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• This example is for vehicles not equipped with a TCS and DSC.
1. DTCs for the PCM, ABS HU/CM and instrument cluster can be verified using a SST (WDS or equivalent).
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Module
|
Displayed DTC
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Probable malfunction location
|
|
PCM
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U0073
|
PCM-related CAN system malfunction
|
|
U0121
|
Communication error between PCM and ABS HU/CM
|
|
U0155
|
Communication error between PCM and instrument cluster
|
|
ABS HU/CM
|
U1900, U2516
|
ABS HU/CM-related CAN system malfunction
|
|
Instrument cluster
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U1900, U2516
|
Instrument cluster-related CAN system malfunction
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2. PID/data monitor information for the PCM, ABS HU/CM can be verified using an SST (WDS or equivalent).
|
Module
|
PID name (definition)
|
Condition
|
Probable malfunction point
|
|
ABS HU/CM
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PCM MSG
(Missing message from the PCM)
|
Not Present
|
Communication error between ABS HU/CM and PCM
|
|
IC MSG
(Missing message from the instrument cluster)
|
Present
|
Normal communication between ABS HU/CM and instrument cluster
|
|
Instrument cluster
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PCM MSG
(Missing message from the PCM)
|
Not Present
|
Communication error between instrument cluster and PCM
|
|
ABS MSG
(Missing message from the ABS (ABS/TCS) HU/CM
|
Present
|
Normal communication between instrument cluster and ABS HU/CM
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3. If there is a communication error between the ABS HU/CM and PCM, or between the instrument cluster and PCM, even if the communication between the ABS HU/CM and the instrument cluster is normal, it is probable that there is a malfunction in the PCM or PCM-related wiring harnesses.