Diagnosis Item
15: Diagnose when the M.U.T.-III cannot receive the data sent by SRS-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
The diagnostic result demonstrates that "the M.U.T.-III cannot receive the sent data from
the SRS-ECU" when the M.U.T.-III checks the periodically sent data from each ECU and cannot
receive the SRS-ECU data only.
TROUBLE JUDGEMENT CONDITIONS
M.U.T.-III judges the trouble when the periodically sent data from SRS-ECU cannot be received.
PROBABLE CAUSES
- Damaged harness wires and connectors
- Power supply circuit malfunction of the SRS-ECU
- Malfunction of the SRS-ECU
|
STEP 1. Connector check: joint connector (CAN1), joint connector
(CAN2) and SRS-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 joint connector (CAN1) and joint
connector (CAN2).
|
|
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 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. For details refer to .
|
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.
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 (CAN1) and the joint connector (CAN2).
|
|
|
|
STEP 3. Resistance measurement at joint connector (CAN2) and SRS-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 joint connector (CAN2) and the SRS-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 joint connector (CAN2) terminal No.6 and SRS-ECU connector terminal
No.33. OK: Continuity (2 Ω or less)
|
|
(5)Continuity between joint connector (CAN2) terminal No.17 and SRS-ECU connector
terminal No.34. 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> Power supply
to the SRS-ECU may be suspected. Diagnose the SRS (Refer to GROUP 52B - Troubleshooting ).
|
|
|
|
NO : <Either or all of the resistances measure more than 2 Ω> Repair
the wiring harness between joint connector (CAN2) and the SRS-ECU connector.
|
|
|