Diagnosis Item 1: Diagnose when the M.U.T.-III cannot receive the data sent by ETACS-ECU
caution
When servicing a CAN bus line, earth yourself by touching a metal object such as an unpainted water pipe. If you fail to do, a component connected to the CAN bus line may be broken.
FUNCTION
When the CAN bus diagnosis is carried out, the M.U.T.-III communicates with the ETACS-ECU. If a communication flag is not set for the ETACS-ECU, the ETACS-ECU will be diagnosed as a communication error.
TRUBLE JUDGEMENT CONDITIONS
If a communication flag is not set for the ETACS-ECU, the ETACS-ECU determines that there is a failure.
TROUBLESHOOTING HINTS
Malfunction of the connector (diagnosis connector or ETACS-ECU connector improperly connected)
Malfunction of the wiring harness (open circuit, short to earth, short to power supply between the diagnosis connector and the ETACS-ECU connector, line-to-line short, or power supply to the ETACS-ECU)
The strand end of the twist wire should be within 10 cm from the connector. For details refer to .
Q.
Is the check result normal?
Go to Step 2.
Repair the defective connector.
STEP 2. Check the wiring harness between C-127 diagnosis connector and C-301 ETACS-ECU connector
caution
Strictly observe the specified wiring harness repair procedure. For details refer to .
(1)Disconnect the M.U.T.-III and ETACS-ECU connector, and check the wiring harness.
(2)Check the wiring harness between C-127 diagnosis connector terminal No.6 and ETACS-ECU connector terminal No.5 <CAN_H>
(3)Check the wiring harness between C-127 diagnosis connector terminal No.14 and ETACS-ECU connector terminal No.4 <CAN_L>
Q.
Is the check result normal?
Go to Step 3.
Repair the wiring harness.
STEP 3. Check the wiring harness between C-127 diagnosis connector and C-301 ETACS-ECU connector for short to earth (resistance measurement).
caution
Disconnect the negative battery terminal. For details refer to .
A digital multimeter should be used. For details refer to .
The test wiring harness should be used. For details refer to .
Strictly observe the specified wiring harness repair procedure. For details refer to .
(1)Disconnect the M.U.T.-III and the ETACS-ECU connector, and measure at the wiring harness side.
(2)Measure the resistance between C-127 diagnosis connector terminal No.6 and body earth. <CAN_H> OK: 1 kΩ or more
(3)Measure the resistance between C-127 diagnosis connector terminal No.14 and body earth. <CAN_L> OK: 1 kΩ or more
Q.
Is the check result normal?
Go to Step 4.
Repair the wiring harness.
STEP 4. Check the wiring harness between C-127 diagnosis connector and C-301 ETACS-ECU connector for short to power supply (voltage measurement).
caution
A digital multimeter should be used. For details refer to .
The test wiring harness should be used. For details refer to .
Strictly observe the specified wiring harness repair procedure. For details refer to .
(1)Disconnect the M.U.T.-III and the ETACS-ECU connector, and measure at the wiring harness side.
(2)Measure the voltage between C-127 diagnosis connector terminal No.6 and body earth. <CAN_H> OK: 5 V or less
(3)Measure the voltage between C-127 diagnosis connector terminal No.14 and body earth. <CAN_L> OK: 5 V or less
Q.
Is the check result normal?
Go to Step 5.
Repair the wiring harness.
STEP 5. Check the wiring harness between C-127 diagnosis connector and C-301 ETACS-ECU connector for line-to-line short (resistance measurement).
caution
Disconnect the negative battery terminal. For details refer to .
A digital multimeter should be used. For details refer to .
The test wiring harness should be used. For details refer to .
Strictly observe the specified wiring harness repair procedure. For details refer to .
(1)Disconnect the M.U.T.-III and the ETACS-ECU connector, and check that there is continuity at the harness side.
(2)Check that there is continuity between C-127 diagnosis connector terminal Nos.6 and 14. OK: Continuity exists (2 Ω or less)
Q.
Is the check result normal?
Go to Step 6.
Repair the wiring harness.
STEP 6. Trouble symptom check
Diagnose the CAN bus line, and check that normal condition is displayed.
Q.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).
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Go to Step 2.
Repair the defective connector.
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