Diagnosis Item 17: Diagnose when the M.U.T.-III cannot receive the data sent by resistor <vehicles without ASTC> or ASTC-ECU <vehicles with ASTC>.


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 resistor <vehicles without ASTC> or ASTC-ECU <vehicles with ASTC>

DIAGNOSIS PROCEDURE

STEP 1. Connector check: D-22 joint connector (CAN2) and D-42 resistor connector <vehicles without ASTC> or D-223 ASTC-ECU connector <vehicles with ASTC>
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-40 resistor connector <vehicles without ASTC> or D-223 ASTC-ECU connector <vehicles with ASTC>.
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 resistor connector <vehicles without ASTC> or ASTC-ECU connector <vehicles with ASTC>, 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-42 resistor connector terminal No.1 <3000 (vehicles without ASTC) >
OK: Continuity (2 Ω or less)
(5)Continuity between D-22 joint connector (CAN2) terminal No.11 and D-42 resistor connector terminal No.2 <3000 (vehicles without ASTC) >
OK: Continuity (2 Ω or less)
(6)Continuity between D-22 joint connector (CAN2) terminal No.6 and D-223 ASTC-ECU connector terminal No.83 <3000 (vehicles with ASTC), 3800>
OK: Continuity (2 Ω or less)
(7)Continuity between D-22 joint connector (CAN2) terminal No.11 and D-223 ASTC-ECU connector terminal No.84 <3000 (vehicles with ASTC), 3800>
OK: Continuity (2 Ω or less)
(8)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)
(9)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 measures more than 2 Ω> Repair the wiring harness between joint connector (CAN2) and resistor connector <vehicles without ASTC> or ASTC-ECU connector <vehicles with ASTC>.

STEP 3. Resistance measurement at D-42 resistor connector <vehicles without ASTC> or D-223 ASTC-ECU connector <vehicles with ASTC>.
caution A digital multimeter should be used. For details refer to .
(1)Remove the resistor <vehicles without ASTC> or ASTC-ECU <vehicles with ASTC>, and measure at the equipment side.
(2)Resistance at D-42 resistor connector terminal Nos.1 and 2 <vehicles without ASTC>
OK: 120 ± 20 Ω
(3)Resistance at D-223 ASTC-ECU connector terminal Nos.83 and 84 <vehicles with ASTC>
OK: 120 ± 20 Ω

Q. Is the check result normal?
<Within 120 ± 20 Ω> The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use troubleshooting/Inspection Service Points ) <vehicles without ASTC>, or power supply to the ASTC-ECU may be suspected. Diagnose the ASTC (Refer to ) <vehicles with ASTC>.
<Not within 120 ± 20 Ω> Replace the resistor <vehicles without ASTC> or ASTC-ECU <vehicles with ASTC>.