Inspection Procedure 12: Check the CAN box unit power supply circuit.


caution Before replacing the CAN box unit, ensure that the power supply circuit, the earth circuit, and the communication circuit are normal. (Check that the voltage is 10 V or more.)










TECHNICAL DESCRIPTION (COMMENT)



PROBABLE CAUSES



  • The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector
  • The CAN box unit may be defective

DIAGNOSIS PROCEDURE

STEP 1. Connector check: C-54 CAN box unit connector

Q. Is the check result normal?
Go to Step 2.
Repair or replace the damaged component(s).

STEP 2. Resistance measurement at C-54 CAN box unit connector.
(1)Disconnect C-54 CAN box unit connector and measure the resistance available at the wiring harness side of the connector.
(2)Check the continuity between C-54 CAN box unit connector terminal No.1 and body earth.
OK: Continuity exists (2 ohms or less)

Q. Is the check result normal?
Go to Step 4.
Go to Step 3.

STEP 3. Check the wiring harness between C-54 CAN box unit connector terminal No.1 and the body earth.

  • Check the earth wires for open circuit.
note Prior to the wiring harness inspection, check intermediate connector C-139, and repair if necessary.

Q. Is the check result normal?
No action is necessary and testing is complete.
Repair the wiring harness.

STEP 4. Voltage measurement at C-54 CAN box unit connector
(1)Disconnect C-54 CAN box unit connector and measure the voltage available at the wiring harness side of the connector.
(2)Measure the voltage between C-54 CAN box unit connector terminal No.2 and body earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 6.
Go to Step 5.

STEP 5. Check the wiring harness between C-54 CAN box unit connector terminal No.2 and C-317 ETACS-ECU connector terminal No.1.

  • Check the power supply lines (battery power supply) for open circuit or short circuit.
note Prior to the wiring harness inspection, check intermediate connector C-139, and repair if necessary.

Q. Is the check result normal?
No action is necessary and testing is complete.
Repair the wiring harness.

STEP 6. Check the wiring harness between C-54 CAN box unit connector terminal No.10 and C-315 ETACS-ECU connector terminal No.9.

  • Check the power supply lines (battery power supply) for open circuit or short circuit.
note Prior to the wiring harness inspection, check intermediate connector C-139 and joint connector C-02 <LHD> or C-46 <RHD, and repair if necessary.

Q. Is the check result normal?
No action is necessary and testing is complete.
Repair the wiring harness.