Diagnosis Item 15: 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.
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FUNCTION
The diagnostic result demonstrates that
"the M.U.T.-III cannot receive the sent data from the resistor <vehicles without ASTC> or ASTC-ECU <vehicles with ASTC>"
when the M.U.T.-III checks the periodically sent data from each ECU and cannot
receive the resistor <vehicles without ASTC> or ASTC-ECU
<vehicles with ASTC>.
TROUBLE JUDGEMENT CONDITIONS
M.U.T.-III judges the trouble when
the periodically sent data from resistor <vehicles without ASTC>
or ASTC-ECU <vehicles with ASTC> cannot be received and
sent.
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>
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STEP 1. Connector check: D-22 joint connector (CAN2) and D-40 resistor
connector <vehicles without ASTC> or D-223 ASTC-ECU connector
<vehicles with ASTC>
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| caution |
The strand end of the twist wire should be within
10 cm from the connector. For details refer to  .
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When checking the joint connector, ensure that
its wiring harness side and its short pins are not damaged.
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Q.
Is the check result normal?
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 Go to Step 2.
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 Repair
the defective connector. Replace the joint connector as necessary.
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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>.
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| caution |
A digital multimeter should be used. For details
refer to .
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| caution |
The test wiring harness should be used. For details
refer to .
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(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.
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(2)Turn the ignition switch to the LOCK (OFF)
position.
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(3)
| caution |
When measuring the resistance, disconnect the
negative battery terminal. For details refer to .
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Ensure that the negative battery terminal is disconnected.
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(4)Continuity between D-22 joint connector (CAN2) terminal
No.6 and D-40 resistor connector terminal No.1 <vehicles without
ASTC>
OK: Continuity (2 Ω or less)
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(5)Continuity between D-22 joint connector (CAN2) terminal
No.11 and D-40 resistor connector terminal No.2 <vehicles without
ASTC>
OK: Continuity (2 Ω or less)
| caution |
Strictly observe the specified wiring harness repair
procedure. For details refer to .
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(6)Continuity between D-22 joint connector (CAN2) terminal
No.6 and D-223 ASTC-ECU connector terminal No.83 <vehicles with
ASTC>
OK: Continuity (2 Ω or less)
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(7)Continuity between D-22 joint connector (CAN2) terminal
No.11 and D-223 ASTC-ECU connector terminal No.84 <vehicles with
ASTC>
OK: Continuity (2 Ω or less)
| caution |
Strictly observe the specified wiring harness repair
procedure. For details refer to .
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Q.
Is the check result normal?
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<All the resistances
measure 2 Ω or less> Go to Step 3.
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NO : <Either or all of the resistances
measure 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>.
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STEP 3. Resistance measurement at D-40 resistor connector
<vehicles without ASTC> or D-223 ASTC-ECU connector
<vehicles with ASTC>.
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| caution |
A digital multimeter should be used. For details
refer to .
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(1)Remove the resistor <vehicles without ASTC> or
ASTC-ECU <vehicles with ASTC>, and measure at the equipment
side.
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(2)Resistance at D-40 resistor connector terminal Nos.1 and 2
<vehicles without ASTC>
OK: 120 ± 20
Ω
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(3)Resistance at D-223 ASTC-ECU connector terminal Nos.83 and
84 <vehicles with ASTC>
OK: 120 ± 20
Ω
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Q.
Is the check result normal?
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<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>.
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<Not within 120 ± 20
Ω> Replace the resistor <vehicles without ASTC> or
the ASTC-ECU <vehicles with ASTC>.
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