Diagnosis Item 17: Diagnose when the M.U.T.-III cannot receive the data sent by ASTC-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 ASTC-ECU
Malfunction of the ASTC-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: D-22 joint connector (CAN2) and D-223 ASTC-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 D-22 joint connector (CAN2) and D-223 ASTC-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 (CAN2) and the ASTC-ECU 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)Continuity between D-22 joint connector (CAN2) terminal No.6 and D-223 ASTC-ECU connector terminal No.83 <3800>
OK: Continuity (2 Ω or less)

(5)Continuity between D-22 joint connector (CAN2) terminal No.11 and D-223 ASTC-ECU connector terminal No.84 <3800>
OK: Continuity (2 Ω or less)

(6)Continuity between D-22 joint connector (CAN2) terminal No.1 and D-223 ASTC-ECU connector terminal No.83 <3200>
OK: Continuity (2 Ω or less)

(7)Continuity between D-22 joint connector (CAN2) terminal No.12 and D-223 ASTC-ECU connector terminal No.84 <3200>
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.

	NO : <Either or all of the resistances measure more than 2 Ω> Repair the wiring harness between joint connector (CAN2) and ASTC-ECU connector.

STEP 3. Resistance measurement at D-223 ASTC-ECU connector.

caution

A digital multimeter should be used. For details refer to

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

(2)Resistance at D-223 ASTC-ECU connector terminal Nos.83 and 84
OK: 120 ± 20 Ω

Q. Is the check result normal?

	<Within 120 ± 20 Ω> Power supply to the ASTC-ECU may be suspected. Diagnose the ASTC. Refer to GROUP 35C, Diagnosis code chart .

	<Not within 120 ± 20 Ω> Replace the ASTC-ECU.