Diagnosis Item 8: Diagnose when the M.U.T.-III cannot receive the data sent by EPS-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 EPS-ECU
  • Malfunction of the EPS-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-24 joint connector (CAN1), B-114 EPS-ECU and B-27 intermediate 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-27 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 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.8 and B-27 intermediate connector terminal No.4
OK: Continuity (2 Ω or less)

(5)Continuity between B-24 joint connector (CAN1) terminal No.19 and B-27 intermediate connector terminal No.17
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-27).

STEP 3. Resistance measurement at B-27 intermediate connector and B-114 EPS-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 EPS-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-27 intermediate connector terminal No.4 and B-114 EPS-ECU connector terminal No.6
OK: Continuity (2 Ω or less)

(5)Continuity between B-27 intermediate connector terminal No.17 and B-114 EPS-ECU connector terminal No.5
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-27) and the EPS-ECU connector.

STEP 4. Resistance measurement at B-114 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 B-114 EPS-ECU connector terminal Nos.5 and 6
OK: 120 ± 20 Ω
caution Strictly observe the specified wiring harness repair procedure. For details refer to .

Q. Is the check result normal?

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

<Less than 1 kΩ> Replace the EPS-ECU.