Diagnosis Item
16: Diagnose when the M.U.T.-III cannot receive the data sent by A/C control unit.
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/C control unit" when the M.U.T.-III checks the periodically sent data from each ECU.
TROUBLE JUDGEMENT CONDITIONS
M.U.T.-III judges the trouble when the periodically sent data from A/C control unit cannot
be received.
PROBABLE CAUSES
Damaged harness wires and connectors
Power supply circuit malfunction of the A/C control unit
Malfunction of the A/C control unit
DIAGNOSIS PROCEDURE
STEP 1. Connector check: C-103 joint
connector (CAN2) and C-101 A/C control unit 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 C-103 joint connector (CAN2) and
C-101 A/C control unit 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 A/C control unit connector, and measure
at the wiring harness side.
(2)Turn the electric motor switch to the LOCK (OFF) position.
(3)
caution
When measuring the resistance, disconnect the negative auxiliary
battery terminal. For details refer to .
Ensure that the negative auxiliary battery terminal is disconnected.
(4)Continuity between C-103 joint connector (CAN2) terminal No.10 and C-101 A/C control unit
connector terminal No.3 OK: Continuity (2 Ω or less)
(5)Continuity between C-103 joint connector (CAN2) terminal No.21 and C-101 A/C control unit
connector terminal No.4 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.
<Either or all of the resistances measure more than 2 Ω> Repair
the wiring harness between joint connector (CAN2) and the A/C control unit connector.
STEP 3. Resistance measurement at C-101 A/C control unit connector
connector.
caution
A digital multimeter should be used. For details refer to .
(1)Remove the A/C control unit, and measure at the equipment side.
(2)Resistance between C-101 A/C control unit connector terminal Nos.3 and 4 OK: 1 kΩ or more
Q.
Is the check result normal?
<1 kΩ or more> Power supply to the A/C control unit
may be suspected. Diagnose the A/C control unit. Refer to .
)
)
)
Go to Step 2
Repair the defective connector. Replace the joint connector as necessary.)
)
)
.