Diagnosis Item 22: Diagnose the lines from the main bus line to the A/C-ECU <Vehicles with A/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.


TROUBLE JUDGMENT


If the M.U.T.-III cannot receive signal from the A/C-ECU, CAN bus line connector(s) are broken or an open circuit has occurred.

COMMENTS ON TROUBLE SYMPTOM


The CAN bus line wiring harness wire or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector, or the A/C-ECU may be defective.

POSSIBLE CAUSES



DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-03 joint connector (CAN1) connector and B-113 A/C-ECU connector


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. Are the check results normal?

Go to Step 2.

Repair a defective connector or replace the joint connector.

STEP 2. Resistance measurement at B-03 joint connector (CAN1) and B-113 A/C-ECU 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 joint connector (CAN1) and the A/C-ECU connector, and measure at the wiring harness side.
(2)Ignition switch: OFF (LOCK)
(3)
caution When measuring the resistance, disconnect the negative battery terminal. For details refer to .
Ensure that the negative battery terminal is disconnected.

(4)Continuity between B-03 joint connector (CAN1) terminal No.6 and B-113 A/C-ECU connector terminal No.6 <L.H. drive vehicles>
OK: 2 ohms or less

(5)Continuity between B-03 joint connector (CAN1) terminal No.17 and B-113 A/C-ECU connector terminal No.7 <L.H. drive vehicles>
OK: 2 ohms or less

(6)Continuity between B-03 joint connector (CAN1) terminal No.3 and B-113 A/C-ECU connector terminal No.6 <R.H. drive vehicles>
OK: 2 ohms or less

(7)Continuity between B-03 joint connector (CAN1) terminal No.14 and B-113 A/C-ECU connector terminal No.7 <R.H. drive vehicles>
OK: 2 ohms or less
caution Strictly observe the specified wiring harness repair procedure. For details refer to .

Q. Are the check results normal?

<All the resistances measure 2 Ω or less> Power supply to the A/C-ECU may be suspected. Diagnose the A/C system. Refer to .

<Either or all of the voltages measure more than 2 Ω> Repair the wiring harness between the joint connector (CAN1) and the A/C-ECU connector.