Diagnosis Item 1: Communication with no ECUs is possible (CAN-C).

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.

TROUBLESHOOTING HINTS

Malfunction in CAN-C (short to earth or power supply, wire short to one another)
Malfunction in the ECUs which are interconnected via CAN-C (internal error)
Malfunction (open circuit) of wiring harness, connector (s) between the diagnosis connector and joint connector(s)

DIAGNOSIS PROCEDURE

STEP 1. Check the CAN-C for short to power supply. Voltage measurement at diagnosis connector.

caution

A digital multimeter should be used. For details refer to

caution

The test wiring harness should be used. For details refer to

(1)Connect the negative battery terminal, and turn the ignition switch to the ON position.

(2)Voltage between diagnosis connector terminal No.6 (CAN_H) and body earth
OK: Less than 4.0 V

(3)Voltage between diagnosis connector terminal No.14 (CAN_L) and body earth
OK: Less than 4.0 V

Q. Is the check result normal?

	YES <Voltage is less than 4.0 V in both CAN_H and CAN_L> : Go to Step 2.

	NO <Voltage is 4.0 V or more in either CAN_H or CAN_L> : Perform diagnosis item 2 "Diagnose shorts in the power supply to CAN-C". Refer to .

STEP 2. Check the CAN-C for short to earth. Resistance measurement at diagnosis connector.

caution

A digital multimeter should be used. For details refer to

caution

The test wiring harness should be used. For details refer to

(1)Turn the ignition switch to the LOCK (OFF) position.

(2)

caution

When measuring the resistance, disconnect the negative battery terminal. For details refer to

Ensure that the negative battery terminal is disconnected.

(3)Resistance between diagnosis connector terminal No.6 (CAN_H) and body earth
OK: 1 kΩ or more

(4)Resistance between diagnosis connector terminal No.14 (CAN_L) and body earth
OK: 1 kΩ or more

Q. Is the check result normal?

	YES <Resistance value is 1 kΩ or more in both CAN_H and CAN_L> : Go to Step 3.

	NO <Resistance value is less than 1 kΩ in either CAN_H or CAN_L> : Perform diagnosis item 3 "Diagnose shorts in the earth to CAN-C". Refer to .

STEP 3. Check the CAN-C for short to each other. Resistance measurement at diagnosis connector.

caution

A digital multimeter should be used. For details refer to

caution

The test wiring harness should be used. For details refer to

(1)Turn the ignition switch to the LOCK (OFF) position.

(2)

caution

When measuring the resistance, disconnect the negative battery terminal. For details refer to

Ensure that the negative battery terminal is disconnected.

(3)Resistance between diagnosis connector terminal Nos.6 and 14
OK: 60 ± 10 Ω

Q. Is the check result normal?

	YES : The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).

	NO <Resistance value is less than 60 ± 10 Ω> : Perform diagnosis Item 4 "Diagnose shorts between CAN_H and L lines (CAN-C)". Refer to .

	NO <Resistance value is 1 kΩ or more> : Check the wires between diagnosis connector and joint connector (CAN3) <LHD> or (CAN4) <RHD> for open circuit, and check the terminal resistors in the engine-ECU and the ETACS-ECU for open circuit. Then repair or replace if necessary.