Diagnosis Item 17: Diagnose when the M.U.T.-III cannot receive the data sent by A/T-ECU <Vehicles with A/T for RHD>.
| 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
The diagnostic result demonstrates that "the M.U.T.-III cannot receive the sent data from the A/T-ECU" when the M.U.T.-III checks the periodically sent data from each ECU and cannot receive the A/T-ECU data only.
TROUBLE JUDGEMENT CONDITIONS
M.U.T.-III judges the trouble when the periodically sent data from A/T-ECU cannot be received.
PROBABLE CAUSES
- Damaged harness wires and connectors
- Power supply circuit malfunction of the A/T-ECU
- Malfunction of the A/T-ECU
|
|
STEP 1. Connector check: joint connector (CAN1), joint connector (CAN2) and A/T-ECU connector
|
|
|
| caution |
The strand end of the twist wire should be within 10 cm from the connector.
|
|
|
|
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 joint connector (CAN1) and joint connector (CAN2).
|
|
|
| caution |
A digital multimeter should be used.
|
|
|
|
| caution |
The test wiring harness should be used.
|
|
|
|
(1)Disconnect joint connector (CAN1) and the joint connector (CAN2), 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.
|
Ensure that the negative battery terminal is disconnected.
|
|
|
(4)Continuity between joint connector (CAN1) terminal No.10 and joint connector (CAN2) terminal No.7.
OK: Continuity (2 Ω or less)
|
|
|
(5)Continuity between joint connector (CAN1) terminal No.21 and joint connector (CAN2) terminal No.18.
OK: Continuity (2 Ω or less)
| caution |
Strictly observe the specified wiring harness repair procedure.
|
|
|
|
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 (CAN1) and the joint connector (CAN2).
|
|
|
|
|
|
STEP 3. Resistance measurement at joint connector (CAN2) and A/T-ECU connector.
|
|
|
| caution |
A digital multimeter should be used.
|
|
|
|
| caution |
The test wiring harness should be used.
|
|
|
|
(1)Disconnect joint connector (CAN2) and the A/T-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.
|
Ensure that the negative battery terminal is disconnected.
|
|
|
(4)Continuity between joint connector (CAN2) terminal No.1 and A/T-ECU connector terminal No.76. <Vehicles with 8A/T>
OK: Continuity (2 Ω or less)
|
|
|
(5)Continuity between joint connector (CAN2) terminal No.12 and A/T-ECU connector terminal No.75. <Vehicles with 8A/T>
OK: Continuity (2 Ω or less)
|
|
|
(6)Continuity between joint connector (CAN2) terminal No.1 and A/T-ECU connector terminal No.16. <Vehicles with 5A/T>
OK: Continuity (2 Ω or less)
|
|
|
(7)Continuity between joint connector (CAN2) terminal No.12 and A/T-ECU connector terminal No.24. <Vehicles with 5A/T>
OK: Continuity (2 Ω or less)
| caution |
Strictly observe the specified wiring harness repair procedure.
|
|
|
|
Q.
Is the check result normal?
|
|
|
<All the resistances measure 2 Ω or less> Power supply to the A/T-ECU may be suspected. Diagnose the A/T (Refer to GROUP 23C - Troubleshooting  ).
|
|
|
|
|
|
NO : <Either or all of the resistances measure more than 2 Ω> Check the intermediate connector, and repair if necessary. If the intermediate connector is in good condition, repair the wiring harness between joint connector (CAN2) and the A/T-ECU connector.
|
|
|
|