54C-DIAGNOSTICS ITEM 4

Diagnostic Item 4: Diagnose shorts between CAN_H and L lines

caution

When servicing a CAN bus line, ground 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.

TROUBLE JUDGMENT

When all of the following conditions are met, the scan tool (M.U.T.-III) determines that a short circuit is present between CAN_L and CAN_H lines.

The scan tool (M.U.T.-III) cannot receive the periodic transmission data from any ECUs.
The voltage between CAN bus lines (CAN_L and CAN_H lines) is 1.0 V or more, 4.0 V or less.
The resistance at CAN bus line (CAN_L and CAN_H lines) is 2 Ω or less.

TROUBLESHOOTING HINTS

Malfunction of the wiring harness
Malfunction of the connector
Malfunction of the ETACS-ECU
Malfunction of the combination meter
Malfunction of the SRS-ECU
Malfunction of the occupant classification-ECU
Malfunction of the KOS-ECU <Vehicles with KOS>
Malfunction of the OSS-ECU <Vehicles with KOS>
Malfunction of the auto A/C controller assembly (A/C-ECU) <Vehicles with automatic A/C>
Malfunction of the steering wheel sensor
Malfunction of the EPS-ECU
Malfunction of the ASC-ECU
Malfunction of the transaxle control module (TCM) <CVT>
Malfunction of the engine control module (ECM)
Malfunction of the PTC heater control unit <ECU for signal reception only>

DIAGNOSIS

STEP 1. Connector check: C-212 intermediate connector

caution

The strand end of the twist wire should be within 10 cm (4 inches) from the connector. For details refer to

Is the check result normal?

Go to Step 2

Repair the defective connector.

STEP 2. Resistance measurement at C-212 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 front 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-212 intermediate connector terminal No.17 and 8

OK: 120 ± 20 Ω

Is the check result normal?

<Within 120 ± 20 Ω> Go to Step 14

<Not within 120 ± 20 Ω> Go to Step 3

STEP 3. Connector check: 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.

Is the check result normal?

Go to Step 4

Repair a defective connector or replace the joint connector.

STEP 4. Resistance measurement at 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 joint connector (CAN2) terminal No.11 and 22

OK: 120 ± 20 Ω

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

Is the check result normal?

<Within 120 ± 20 Ω> Go to Step 6

<Not within 120 ± 20 Ω> Go to Step 5

STEP 5. Resistance measurement at engine control module (ECM) connector.

caution

A digital multimeter should be used. For details refer to

(1) Remove the engine control module (ECM), and measure at the equipment side.

(2) Resistance between engine control module (ECM) connector terminal No.71 and 72

OK: 120 ± 20 Ω

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

Is the check result normal?

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

<Not within 120 ± 20 Ω> Check the engine control module (ECM) connector, and repair if necessary. If the engine control module (ECM) connector is in good condition, replace the engine control module (ECM).

STEP 6. Resistance measurement at 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 joint connector (CAN2) terminal No.7 and 18

OK: 1 kΩ or more

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

Is the check result normal?

<1 kΩ or more> Go to Step 8

<Less than 1 kΩ> Go to Step 7

STEP 7. Resistance measurement at transaxle control module (TCM) connector.

caution

A digital multimeter should be used. For details refer to

(1) Remove the transaxle control module (TCM), and measure at the equipment side.

(2) Resistance between transaxle control module (TCM) connector terminal No.9 and 10

OK: 1 kΩ or more

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

Is the check result normal?

<1 kΩ or more> Check intermediate connector, and repair if necessary. If the intermediate connector is in good condition, repair the wiring harness between joint connector (CAN2) and the transaxle control module (TCM) connector.

<Less than 1 kΩ> Check the transaxle control module (TCM) connector, and repair if necessary. If the transaxle control module (TCM) connector is in good condition, replace the transaxle control module (TCM).

STEP 8. Resistance measurement at 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 joint connector (CAN2) terminal No.9 and 20

OK: 1 kΩ or more

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

Is the check result normal?

<1 kΩ or more> Go to Step 10

<Less than 1 kΩ> Go to Step 9

STEP 9. Resistance measurement at ASC-ECU connector.

caution

A digital multimeter should be used. For details refer to

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

(2) Resistance between ASC-ECU connector terminal No.26 and 14

OK: 1 kΩ or more

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

Is the check result normal?

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

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

STEP 10. Resistance measurement at 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 joint connector (CAN2) terminal No.8 and 19

OK: 1 kΩ or more

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

Is the check result normal?

<1 kΩ or more> Go to Step 12

<Less than 1 kΩ> Go to Step 11

STEP 11. Resistance measurement at EPS-ECU connector.

caution

A digital multimeter should be used. For details refer to

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

(2) Resistance between EPS-ECU connector terminal No.3 and 4

OK: 1 kΩ or more

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

Is the check result normal?

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

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

STEP 12. Resistance measurement at 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 joint connector (CAN2) terminal No.5 and 16

OK: 1 kΩ or more

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

Is the check result normal?

<1 kΩ or more> Repair the wiring harness between joint connector (CAN2) and C-212 intermediate connector.

<Less than 1 kΩ> Go to Step 13

STEP 13. Resistance measurement at PTC heater control unit connector.

caution

A digital multimeter should be used. For details refer to

(1) Remove the PTC heater control unit, and measure at the equipment side.

(2) Resistance between PTC heater control unit connector terminal No.12 and 13

OK: 1 kΩ or more

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

Is the check result normal?

<1 kΩ or more> Repair the wiring harness between joint connector (CAN2) and the PTC heater control unit connector.

<Less than 1 kΩ> Check the PTC heater control unit connector, and repair if necessary. If the PTC heater control unit connector is in good condition, replace the PTC heater control unit.

STEP 14. Connector check: 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.

Is the check result normal?

Go to Step 15

Repair a defective connector or replace the joint connector.

STEP 15. Resistance measurement at 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 joint connector (CAN1) terminal No.10 and 21

OK: 120 ± 20 Ω

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

Is the check result normal?

<Within 120 ± 20 Ω> Go to Step 17

<Not within 120 ± 20 Ω> Go to Step 16

STEP 16. Resistance measurement at 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 ETACS-ECU connector terminal No.56 and 65

OK: 120 ± 20 Ω

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 17. Resistance measurement at 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 joint connector (CAN1) terminal No.6 and 17

OK: 1 kΩ or more

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

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 combination meter connector.

caution

A digital multimeter should be used. For details refer to

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

(2) Resistance at combination meter connector terminal No.14 and 15

OK: 1 kΩ or more

Is the check result normal?

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

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

STEP 19. Resistance measurement at 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 joint connector (CAN1) terminal No.4 and 15

OK: 1 kΩ or more

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

Is the check result normal?

<1 kΩ or more> Go to Step 21

<Less than 1 kΩ> Go to Step 20

STEP 20. Resistance measurement at SRS-ECU connector.

caution

A digital multimeter should be used. For details refer to

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

(2) Resistance at SRS-ECU connector terminal No.30 and 29

OK: 1 kΩ or more

Is the check result normal?

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

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

STEP 21. Resistance measurement at 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 joint connector (CAN1) terminal No.1 and 12

OK: 1 kΩ or more

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

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 occupant classification-ECU connector.

caution

A digital multimeter should be used. For details refer to

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

(2) Resistance at occupant classification-ECU connector terminal No.2 and 4

OK: 1 kΩ or more

Is the check result normal?

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

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

STEP 23. Resistance measurement at 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 joint connector (CAN1) terminal No.11 and 22

OK: 1 kΩ or more

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

Is the check result normal?

<1 kΩ or more> Go to Step 25

<Less than 1 kΩ> Go to Step 24

STEP 24. Resistance measurement at KOS-ECU connector.

caution

A digital multimeter should be used. For details refer to

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

(2) Resistance at KOS-ECU connector terminal No.3 and 2

OK: 1 kΩ or more

Is the check result normal?

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

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

STEP 25. Resistance measurement at 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 joint connector (CAN1) terminal No.5 and 16

OK: 1 kΩ or more

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

Is the check result normal?

<1 kΩ or more> Go to Step 27

<Less than 1 kΩ> Go to Step 26

STEP 26. Resistance measurement at OSS-ECU connector.

caution

A digital multimeter should be used. For details refer to

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

(2) Resistance at OSS-ECU connector terminal No.1 and 14

OK: 1 kΩ or more

Is the check result normal?

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

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

STEP 27. Resistance measurement at 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 joint connector (CAN1) terminal No.7 and 18

OK: 1 kΩ or more

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

Is the check result normal?

<1 kΩ or more> Go to Step 29

<Less than 1 kΩ> Go to Step 28

STEP 28. Resistance measurement at auto A/C controller assembly (A/C-ECU) connector.

caution

A digital multimeter should be used. For details refer to

(1) Remove the auto A/C controller assembly, and measure at the equipment side.

(2) Resistance at auto A/C controller assembly (A/C-ECU) connector terminal No.12 and 11

OK: 1 kΩ or more

Is the check result normal?

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

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

STEP 29. Resistance measurement at 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 joint connector (CAN1) terminal No.3 and 14

OK: 1 kΩ or more

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

Is the check result normal?

<1 kΩ or more> Go to Step 31

<Less than 1 kΩ> Go to Step 30

STEP 30. Resistance measurement at 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 steering wheel sensor connector terminal No.12 and 11

OK: 1 kΩ or more

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 31. Resistance measurement at 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 joint connector (CAN1) terminal No.8 and 19

OK: 1 kΩ or more

caution

Strictly observe the specified wiring harness repair procedure. For details refer to

Is the check result normal?

<1 kΩ or more> Repair the wiring harness between joint connector (CAN1) and the C-212 intermediate connector.

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