Diagnosis Item 7: Diagnose when the M.U.T.-III cannot receive the data sent by ASC-ECU


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 ASC-ECU
  • Malfunction of the ASC-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-01 intermediate connector, B-24 joint connector (CAN1) and A-14 ASC-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. Is the check result normal?

Go to Step 2

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

STEP 2. Resistance measurement at B-24 joint connector (CAN1) and B-01 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 joint connector (CAN1) and the intermediate 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 B-24 joint connector (CAN1) terminal No.9 and B-01 intermediate connector terminal No.3 <LHD>
OK: Continuity (2 Ω or less)

(5)Continuity between B-24 joint connector (CAN1) terminal No.20 and B-01 intermediate connector terminal No.14 <LHD>
OK: Continuity (2 Ω or less)
caution Strictly observe the specified wiring harness repair procedure. For details refer to .

(6)Continuity between B-24 joint connector (CAN1) terminal No.9 and B-01 intermediate connector terminal No.3 <RHD>
OK: Continuity (2 Ω or less)

(7)Continuity between B-24 joint connector (CAN1) terminal No.20 and B-01 intermediate connector terminal No.14 <RHD>
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 (CAN1) and intermediate connector (B-24).

STEP 3. Resistance measurement at B-01 intermediate connector and A-14 ASC-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 intermediate connector and the ASC-ECU 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 B-01 intermediate connector terminal No.3 and A-14 ASC-ECU connector terminal No.26 <LHD>
OK: Continuity (2 Ω or less)

(5)Continuity between B-01 intermediate connector terminal No.14 and A-14 ASC-ECU connector terminal No.14 <LHD>
OK: Continuity (2 Ω or less)
caution Strictly observe the specified wiring harness repair procedure. For details refer to .

(6)Continuity between B-01 intermediate connector terminal No.3 and A-14 ASC-ECU connector terminal No.26 <RHD>
OK: Continuity (2 Ω or less)

(7)Continuity between B-01 intermediate connector terminal No.14 and A-14 ASC-ECU connector terminal No.14 <RHD>
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 4

<Either or all of the resistances measure more than 2 Ω> Repair the wiring harness between intermediate connector (B-01) and the ASC-ECU connector.

STEP 4. Resistance measurement at A-14 ASC-ECU connector.
caution A digital multimeter should be used. For details refer to .

(1)Connect special tool MB991951 to the ASC-ECU connector, and measure by using the check connector (connect the ECU side only).

(2)Measure the resistance between special tool MB991951 check connector terminal Nos. 14 and 26.
OK: 1 kΩ or more

Q. Is the check result normal?

<1 kΩ or more> Power supply to the ASC-ECU may be suspected. Refer to .

<Less than 1 kΩ> Replace the ASC-ECU.