Diagnosis Item 3: Diagnose shorts between CAN_H and L lines


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 JUDGEMENT CONDITIONS



TROUBLESHOOTING HINTS



  • Malfunction of the wiring harness
    note The M.U.T.-III cannot receive all the periodically sent data from each ECU by the open circuit of harness between the diagnosis connector, the joint connector (CAN1) and the joint connector (CAN2). In addition, the M.U.T.-III measures the voltage itself and shows 2.5 V due to the open circuit of harness. Therefore, it is judged as a short between CAN_H and CAN_L line.
  • Malfunction of the connector
  • Malfunction of each ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: C-53 <LHD> or C-35 <RHD> intermediate 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. Resistance measurement at C-53 <LHD> or C-35 <RHD> intermediate 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)Disconnect the connector, and measure at its female-side intermediate connector (at the instrument panel wiring harness side).
(2)Turn the ignition switch to the LOCK (OFF) position.
(3)
caution When measuring the resistance, disconnect the negative battery terminal. For details refer to .
Ensure that the negative battery terminal is disconnected.

(4)Resistance between C-53 <LHD> or C-35 <RHD> intermediate connector terminal Nos.6 and 7
OK: 120 ± 20 Ω

Q. Is the check result normal?

<Within 120 ± 20 Ω> Go to Step 3.

<Not within 120 ± 20 Ω> Go to Step 8.

STEP 3. Connector check: C-01 joint connector (CAN2)


caution The strand end of the twist wire should be within 10 cm from the connector. For details refer to .

When checking the joint connector, ensure that its wiring harness side and its short pins are not damaged.

Q. Is the check result normal?

Go to Step 4.

Repair a defective connector or replace the joint connector.

STEP 4. Resistance measurement at C-01 joint connector (CAN2).
caution A digital multimeter should be used. For details refer to .
caution The test wiring harness should be used. For details refer to .


(1)Disconnect the connector, and measure at the wiring harness side.
(2)Turn the ignition switch to the LOCK (OFF) position.
(3)
caution When measuring the resistance, disconnect the negative battery terminal. For details refer to .
Ensure that the negative battery terminal is disconnected.


(4)Resistance between C-01 joint connector (CAN2) terminal Nos.9 and 20 <LHD>
OK: 120 ± 20 Ω
Resistance between C-01 joint connector (CAN2) terminal Nos.10 and 21 <RHD>
OK: 120 ± 20 Ω
caution Strictly observe the specified wiring harness repair procedure. For details refer to .

Q. Is the check result normal?

YES <M/T> : <Within 120 ± 20 Ω> Repair the wiring harness between joint connector (CAN2) and intermediate connector C-53 <LHD> or C-35 <RHD>.

YES <A/T> : <Within 120 ± 20 Ω> Go to Step 6.

NO : <Not within 120 ± 20 Ω> Go to Step 5.

STEP 5. Resistance measurement at C-103 engine-ECU connector.
caution A digital multimeter should be used. For details refer to .


(1)Remove the engine-ECU, and measure at the equipment side.

(2)Resistance between C-103 engine-ECU connector terminal Nos.108 and 109
OK: 120 ± 20 Ω
caution Strictly observe the specified wiring harness repair procedure. For details refer to .

Q. Is the check result normal?

<Within 120 ± 20 Ω> Repair the wiring harness between joint connector (CAN2) and the engine-ECU connector.

<Not within 120 ± 20 Ω> Check the engine-ECU connector, and repair if necessary. If the engine-ECU connector is in good condition, replace the engine-ECU.

STEP 6. Resistance measurement at C-01 joint connector (CAN2).
caution A digital multimeter should be used. For details refer to .
caution The test wiring harness should be used. For details refer to .


(1)Disconnect the connector, and measure at the wiring harness side.
(2)Turn the ignition switch to the LOCK (OFF) position.
(3)
caution When measuring the resistance, disconnect the negative battery terminal. For details refer to .
Ensure that the negative battery terminal is disconnected.


(4)Resistance between C-01 joint connector (CAN2) terminal Nos.10 and 21 <LHD>
OK: 1 kΩ or more
Resistance between C-01 joint connector (CAN2) terminal Nos.9 and 20 <RHD>
OK: 1 kΩ or more
caution Strictly observe the specified wiring harness repair procedure. For details refer to .

Q. Is the check result normal?

<1 kΩ or more> Repair the wiring harness between joint connector (CAN2) and intermediate connector C-53 <LHD> or C-35 <RHD>.

<Less than 1 kΩ> Go to Step 7.

STEP 7. Resistance measurement at C-20 A/T-ECU connector.
caution A digital multimeter should be used. For details refer to .


(1)Remove the A/T-ECU, and measure at the equipment side.

(2)Resistance between C-20 A/T-ECU connector terminal Nos.53 and 54
OK: 1 kΩ or more
caution Strictly observe the specified wiring harness repair procedure. For details refer to .

Q. Is the check result normal?

<1 kΩ or more> Repair the wiring harness between joint connector (CAN2) and the A/T-ECU connector.

<Less than 1 kΩ> Check the A/T-ECU connector, and repair if necessary. If the A/T-ECU connector is in good condition, replace the A/T-ECU.

STEP 8. Connector check: C-119 joint connector (CAN1)


caution The strand end of the twist wire should be within 10 cm from the connector. For details refer to .

When checking the joint connector, ensure that its wiring harness side and its short pins are not damaged.

Q. Is the check result normal?

Go to Step 9.

Repair a defective connector or replace the joint connector.

STEP 9. Resistance measurement at C-119 joint connector (CAN1).
caution A digital multimeter should be used. For details refer to .
caution The test wiring harness should be used. For details refer to .


(1)Disconnect joint connector (CAN1), and measure at the wiring harness side.
(2)Turn the ignition switch to the LOCK (OFF) position.
(3)
caution When measuring the resistance, disconnect the negative battery terminal. For details refer to .
Ensure that the negative battery terminal is disconnected.

(4)Resistance between C-119 joint connector (CAN1) terminal Nos.9 and 20
OK: 120 ± 20 Ω
caution Strictly observe the specified wiring harness repair procedure. For details refer to .

Q. Is the check result normal?

<Within 120 ± 20 Ω> Go to Step 11.

<Not within 120 ± 20 Ω> Go to Step 10.

STEP 10. Resistance measurement at C-219 ETACS-ECU connector.
caution A digital multimeter should be used. For details refer to .


(1)Remove the ETACS-ECU, and measure at the equipment side.

(2)Resistance at C-219 ETACS-ECU connector terminal Nos.56 and 65
OK: 120 ± 20 Ω

Q. Is the check result normal?

<Within 120 ± 20 Ω> Repair the wiring harness between joint connector (CAN1) and the ETACS-ECU connector.

<Not within 120 ± 20 Ω> Check the ETACS-ECU connector, and repair if necessary. If the ETACS-ECU connector is in good condition, replace the ETACS-ECU.

STEP 11. Resistance measurement at C-119 joint connector (CAN1).
caution A digital multimeter should be used. For details refer to .
caution The test wiring harness should be used. For details refer to .


(1)Disconnect joint connector (CAN1), and measure at the wiring harness side.
(2)Turn the ignition switch to the LOCK (OFF) position.
(3)
caution When measuring the resistance, disconnect the negative battery terminal. For details refer to .
Ensure that the negative battery terminal is disconnected.

(4)Resistance between C-119 joint connector (CAN1) terminal Nos.7 and 18
OK: 1 kΩ or more
caution Strictly observe the specified wiring harness repair procedure. For details refer to .

Q. Is the check result normal?

YES <vehicles without ABS, ASTC and A/C> : <1 kΩ or more> Go to Step 23.

YES <vehicles with ABS> : <1 kΩ or more> Go to Step 13.

YES <vehicles with ASTC> : <1 kΩ or more> Go to Step 15.

YES <vehicles without ABS and ASTC, and with A/C> : <1 kΩ or more> Go to Step 21.

NO : <Less than 1 kΩ> Go to Step 12.

STEP 12. Resistance measurement at C-171 RV meter connector.
caution A digital multimeter should be used. For details refer to .


(1)Remove the RV meter, and measure at the equipment side.

(2)Resistance at C-171 RV meter connector terminal Nos.7 and 21
OK: 1 kΩ or more

Q. Is the check result normal?

<1 kΩ or more> Repair the wiring harness between joint connector (CAN1) and the RV meter connector.

<Less than 1 kΩ> Check the RV meter connector, and repair if necessary. If the RV meter connector is in good condition, replace the RV meter.

STEP 13. Resistance measurement at C-119 joint connector (CAN1).
caution A digital multimeter should be used. For details refer to .
caution The test wiring harness should be used. For details refer to .


(1)Disconnect joint connector (CAN1), and measure at the wiring harness side.
(2)Turn the ignition switch to the LOCK (OFF) position.
(3)
caution When measuring the resistance, disconnect the negative battery terminal. For details refer to .
Ensure that the negative battery terminal is disconnected.

(4)Resistance between C-119 joint connector (CAN1) terminal Nos.5 and 16
OK: 1 kΩ or more
caution Strictly observe the specified wiring harness repair procedure. For details refer to .

Q. Is the check result normal?

YES <vehicles without A/C> : <1 kΩ or more> Go to Step 23.

YES <vehicles with A/C> : <1 kΩ or more> Go to Step 21.

NO : <Less than 1 kΩ> Go to Step 14.

STEP 14. Resistance measurement at A-01 ABS-ECU connector.
caution A digital multimeter should be used. For details refer to .

(1)Remove the ABS-ECU, and measure at the equipment side.

(2)Resistance at A-01 ABS-ECU connector terminal Nos.23 and 34.
OK: 1 kΩ or more

Q. Is the check result normal?

<1 kΩ or more> Check intermediate connector C-13, and repair if necessary. If the intermediate connector C-13 is in good condition, repair the wiring harness between joint connector (CAN1) and the ABS-ECU connector.

<Less than 1 kΩ> Check the ABS-ECU connector, and repair if necessary. If the ABS-ECU connector is in good condition, replace the hydraulic unit assembly.

STEP 15. Resistance measurement at C-119 joint connector (CAN1).
caution A digital multimeter should be used. For details refer to .
caution The test wiring harness should be used. For details refer to .


(1)Disconnect joint connector (CAN1), and measure at the wiring harness side.
(2)Turn the ignition switch to the LOCK (OFF) position.
(3)
caution When measuring the resistance, disconnect the negative battery terminal. For details refer to .
Ensure that the negative battery terminal is disconnected.

(4)Resistance between C-119 joint connector (CAN1) terminal Nos.5 and 16
OK: 1 kΩ or more
caution Strictly observe the specified wiring harness repair procedure. For details refer to .

Q. Is the check result normal?

<1 kΩ or more> Go to Step 17.

<Less than 1 kΩ> Go to Step 16.

STEP 16. Resistance measurement at A-48 ASTC-ECU connector.
caution A digital multimeter should be used. For details refer to .

(1)Remove the ASTC-ECU, and measure at the equipment side.

(2)Resistance at A-48 ASTC-ECU connector terminal Nos.23 and 34
OK: 1 kΩ or more

Q. Is the check result normal?

<1 kΩ or more> Check intermediate connector C-13, and repair if necessary. If the intermediate connector C-13 is in good condition, repair the wiring harness between joint connector (CAN1) and the ASTC-ECU connector.

<Less than 1 kΩ> Check the ASTC-ECU connector, and repair if necessary. If the ASTC-ECU connector is in good condition, replace the hydraulic unit assembly.

STEP 17. Resistance measurement at C-119 joint connector (CAN1).
caution A digital multimeter should be used. For details refer to .
caution The test wiring harness should be used. For details refer to .


(1)Disconnect joint connector (CAN1), and measure at the wiring harness side.
(2)Turn the ignition switch to the LOCK (OFF) position.
(3)
caution When measuring the resistance, disconnect the negative battery terminal. For details refer to .
Ensure that the negative battery terminal is disconnected.

(4)Resistance between C-119 joint connector (CAN1) terminal Nos.3 and 14
OK: 1 kΩ or more
caution Strictly observe the specified wiring harness repair procedure. For details refer to .

Q. Is the check result normal?

<1 kΩ or more> Go to Step 19.

<Less than 1 kΩ> Go to Step 18.

STEP 18. Resistance measurement at C-308 steering wheel sensor connector.
caution A digital multimeter should be used. For details refer to .


(1)Remove the steering wheel sensor, and measure at the equipment side.

(2)Resistance at C-308 steering wheel sensor connector terminal Nos.3 and 4
OK: 1 kΩ or more

Q. Is the check result normal?

<1 kΩ or more> Repair the wiring harness between joint connector (CAN1) and the steering wheel sensor connector.

<Less than 1 kΩ> Check the steering wheel sensor connector, and repair if necessary. If the steering wheel sensor connector is in good condition, replace the steering wheel sensor.

STEP 19. Resistance measurement at C-119 joint connector (CAN1).
caution A digital multimeter should be used. For details refer to .
caution The test wiring harness should be used. For details refer to .


(1)Disconnect joint connector (CAN1), and measure at the wiring harness side.
(2)Turn the ignition switch to the LOCK (OFF) position.
(3)
caution When measuring the resistance, disconnect the negative battery terminal. For details refer to .
Ensure that the negative battery terminal is disconnected.

(4)Resistance between C-119 joint connector (CAN1) terminal Nos.4 and 15
OK: 1 kΩ or more
caution Strictly observe the specified wiring harness repair procedure. For details refer to .

Q. Is the check result normal?

YES <vehicles without A/C> : <1 kΩ or more> Go to Step 23.

YES <vehicles with A/C> : <1 kΩ or more> Go to Step 21.

<Less than 1 kΩ> Go to Step 20.

STEP 20. Resistance measurement at C-144 G and yaw rate sensor connector.
caution A digital multimeter should be used. For details refer to .


(1)Remove the G and yaw rate sensor, and measure at the equipment side.

(2)Resistance at C-144 G and yaw rate sensor connector terminal Nos.2 and 3
OK: 1 kΩ or more

Q. Is the check result normal?

<1 kΩ or more> Repair the wiring harness between joint connector (CAN1) and the G and yaw rate sensor connector.

<Less than 1 kΩ> Check the G and yaw rate sensor connector, and repair if necessary. If the G and yaw rate sensor connector is in good condition, replace the G and yaw rate sensor.

STEP 21. Resistance measurement at C-119 joint connector (CAN1).
caution A digital multimeter should be used. For details refer to .
caution The test wiring harness should be used. For details refer to .


(1)Disconnect joint connector (CAN1), and measure at the wiring harness side.
(2)Turn the ignition switch to the LOCK (OFF) position.
(3)
caution When measuring the resistance, disconnect the negative battery terminal. For details refer to .
Ensure that the negative battery terminal is disconnected.

(4)Resistance between C-119 joint connector (CAN1) terminal Nos.6 and 17
OK: 1 kΩ or more
caution Strictly observe the specified wiring harness repair procedure. For details refer to .

Q. Is the check result normal?

<1 kΩ or more> Go to Step 23.

<Less than 1 kΩ> Go to Step 22.

STEP 22. Resistance measurement at C-43 A/C-ECU connector.
caution A digital multimeter should be used. For details refer to .


(1)Remove the A/C-ECU, and measure at the equipment side.

(2)Resistance at C-43 A/C-ECU connector terminal Nos.6 and 7
OK: 1 kΩ or more

Q. Is the check result normal?

<1 kΩ or more> Repair the wiring harness between joint connector (CAN1) and the A/C-ECU connector.

<Less than 1 kΩ> Check the A/C-ECU connector, and repair if necessary. If the A/C-ECU connector is in good condition, replace the A/C-ECU.

STEP 23. Resistance measurement at C-119 joint connector (CAN1).
caution A digital multimeter should be used. For details refer to .
caution The test wiring harness should be used. For details refer to .


(1)Disconnect the joint connector (CAN1), and measure at the wiring harness side.
(2)Turn the ignition switch to the LOCK (OFF) position.
(3)
caution When measuring the resistance, disconnect the negative battery terminal. For details refer to .
Ensure that the negative battery terminal is disconnected.

(4)Resistance between C-119 joint connector (CAN1) terminal Nos.10 and 21
OK: 1 kΩ or more
caution Strictly observe the specified wiring harness repair procedure. For details refer to .

Q. Is the check result normal?

<1 kΩ or more> Repair the wiring harness between joint connector (CAN1) and the intermediate connector C-53.

<Less than 1 kΩ> Check the diagnosis connector, and repair if necessary. If the diagnosis connector is in good condition, repair the wiring harness between joint connector (CAN1) and the diagnosis connector.