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



TROUBLE JUDGMENT CONDITIONS



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)
  • Malfunction of ETACS-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: C-127 diagnosis connector and C-301 ETACS-ECU connector
caution 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 that there is continuity between C-127 diagnosis connector terminal No.6 and ETACS-ECU connector terminal No.5 <CAN_H>
OK: Continuity exists (2 Ω or less)
(3)Check that there is continuity between C-127 diagnosis connector terminal No.14 and ETACS-ECU connector terminal No.4 <CAN_L>
OK: Continuity exists (2 Ω or less)

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: No continuity

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 ).
Replace the ETACS-ECU.