Diagnosis Item 16: Diagnose when the M.U.T.-III cannot receive the data sent by A/C control unit.


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



PROBABLE CAUSES



  • Damaged harness wires and connectors
  • Power supply circuit malfunction of the A/C control unit
  • Malfunction of the A/C control unit

DIAGNOSIS PROCEDURE

STEP 1. Connector check: C-103 joint connector (CAN2) and C-101 A/C control unit 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. Is the check result normal?

Go to Step 2

Repair the defective connector. Replace the joint connector as necessary.

STEP 2. Resistance measurement at C-103 joint connector (CAN2) and C-101 A/C control unit 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 (CAN2) and the A/C control unit connector, and measure at the wiring harness side.
(2)Turn the electric motor switch to the LOCK (OFF) position.
(3)
caution When measuring the resistance, disconnect the negative auxiliary battery terminal. For details refer to .
Ensure that the negative auxiliary battery terminal is disconnected.

(4)Continuity between C-103 joint connector (CAN2) terminal No.10 and C-101 A/C control unit connector terminal No.3
OK: Continuity (2 Ω or less)

(5)Continuity between C-103 joint connector (CAN2) terminal No.21 and C-101 A/C control unit connector terminal No.4
OK: Continuity (2 Ω or less)
caution Strictly observe the specified wiring harness repair procedure. For details refer to .

Q. Is the check result normal?

<All the resistances measure 2 Ω or less> Go to Step 3.

<Either or all of the resistances measure more than 2 Ω> Repair the wiring harness between joint connector (CAN2) and the A/C control unit connector.

STEP 3. Resistance measurement at C-101 A/C control unit connector connector.
caution A digital multimeter should be used. For details refer to .
(1)Remove the A/C control unit, and measure at the equipment side.

(2)Resistance between C-101 A/C control unit connector terminal Nos.3 and 4
OK: 1 kΩ or more

Q. Is the check result normal?

<1 kΩ or more> Power supply to the A/C control unit may be suspected. Diagnose the A/C control unit. Refer to .

<Less than 1 kΩ > Replace the A/C control unit.