Diagnosis Item
8: Diagnose shorts between CAN_H and L lines (SUB). <Vehicles
with Automatic
A/C>
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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TROUBLE JUDGEMENT
When all of the following conditions are met,
the M.U.T.-III determines that a short circuit
is present between CAN_L and CAN_H lines.
- The M.U.T.-III cannot receive the periodic transmission
data from any ECUs.
- The voltage between CAN sub bus lines (CAN_L and CAN_H lines)
is 1.0 V or more, 4.0 V or less.
- The resistance at CAN sub bus line (CAN_L and CAN_H lines) is
2 Ω or less.
TROUBLESHOOTING HINTS
- Malfunction of the wiring harness
- Malfunction of the connector
- Malfunction of the gateway-ECU <Vehicles with automatic
A/C>
- Malfunction of the A/C-ECU <Vehicles with automatic
A/C>
- Malfunction of the camera-ECU <Vehicles with multi around monitor
system>
- Malfunction of the headlamp automatic levelling-ECU <Vehicles with
auto
headlamp levelling system>
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STEP 1. Connector check: joint connector (CAN4)
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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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![](../../../img/54/ACE02953AB00ENG.png)
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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 a defective connector or
replace the joint connector.
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STEP 2. Resistance measurement at joint connector (CAN4).
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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 joint connector (CAN4), 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)Resistance between joint connector (CAN4) terminal Nos.10
and 21. OK: 120 ± 20 Ω
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Q.
Is the check result normal?
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YES : <Within 120 ± 20
Ω> Go to Step 4.
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NO : <Not within 120 ±
20 Ω> Go to Step 3.
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STEP 3. Resistance measurement at gateway-ECU connector.
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caution |
A digital multimeter should be used. For details
refer to .
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(1)Remove the gateway-ECU, and measure at the equipment
side.
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(2)Resistance between gateway-ECU connector terminal Nos.5
and 6. OK: 120 ± 20 Ω
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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<Within 120 ± 20
Ω> Check intermediate connector, and
repair if necessary. If the intermediate connector is in good condition,
repair the wiring harness between
joint connector (CAN4) and the gateway-ECU connector.
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<Not within 120 ± 20
Ω> Check the gateway-ECU connector,
and repair if necessary. If the gateway-ECU connector is in good condition,
replace the gateway-ECU
(Refer to ).
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STEP 4. Resistance measurement at joint connector (CAN4).
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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 joint connector (CAN4), 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)Resistance between joint connector (CAN4) terminal Nos.1
and 12. OK: 1 kΩ or more
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Q.
Is the check result normal?
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<1 kΩ or more>
Go to Step 6.
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<Less than 1
kΩ> Go to Step 5.
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STEP 5. Resistance measurement at headlamp automatic levelling-ECU
connector.
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caution |
A digital multimeter should be used. For details
refer to .
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(1)Remove the headlamp automatic levelling-ECU, and measure
at the equipment side.
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(2)Resistance between headlamp automatic levelling-ECU
connector terminal Nos.6 and
13. OK: 1 kΩ or more
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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<1 kΩ or more>
Repair the wiring harness between joint
connector (CAN4) and the headlamp automatic levelling-ECU
connector.
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<Less than 1 kΩ>
Check the headlamp automatic levelling-ECU
connector, and repair if necessary. If the headlamp automatic levelling-ECU
connector is in good
condition, replace the headlamp automatic levelling-ECU (Refer to GROUP 54A
- Headlamp Automatic
Levelling System, Headlamp Levelling-ECU ).
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STEP 6. Resistance measurement at joint connector (CAN4).
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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 joint connector (CAN4), 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)Resistance between joint connector (CAN4) terminal Nos.3
and 14. OK: 1 kΩ or more
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Q.
Is the check result normal?
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YES : <1 kΩ or
more> Go to Step 8.
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<Less than 1
kΩ> Go to Step 7.
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STEP 7. Resistance measurement at camera-ECU connector.
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caution |
A digital multimeter should be used. For details
refer to .
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(1)Remove the camera-ECU, and measure at the equipment
side.
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(2)Resistance between camera-ECU connector terminal Nos.1 and
21. OK: 1 kΩ or more
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Q.
Is the check result normal?
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<1 kΩ or more>
Repair the wiring harness between joint
connector (CAN4) and the camera-ECU connector.
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<Less than 1 kΩ>
Check the camera-ECU connector, and
repair if necessary. If the camera-ECU connector is in good condition,
replace the camera-ECU
(Refer to GROUP 54A - Camera System, Camera-ECU ).
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STEP 8. Resistance measurement at joint connector (CAN4).
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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 joint connector (CAN4), 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)Resistance between joint connector (CAN4) terminal Nos.11
and 22. OK: 120 ± 20 Ω
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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<Within 120 ± 20
Ω> The trouble can be an intermittent
malfunction (Refer to GROUP 00 - How to Use
Troubleshooting/inspection Service
Points - How to Cope with Intermittent Malfunction ).
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<Not within 120 ± 20
Ω> Go to Step 9.
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STEP 9. Resistance measurement at A/C-ECU connector.
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caution |
A digital multimeter should be used. For details
refer to .
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(1)Remove the A/C-ECU, and measure at the equipment
side.
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(2)Resistance between A/C-ECU connector terminal Nos.1 and
2. OK: 120 ± 20 Ω
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Q.
Is the check result normal?
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<Within 120 ± 20
Ω> Repair the wiring harness between
joint connector (CAN4) and the A/C-ECU connector.
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<Not within 120 ± 20
Ω> Check the A/C-ECU connector,
and repair if necessary. If the A/C-ECU connector is in good condition,
replace the A/C-ECU (Refer
to GROUP 55B - Heater Control Unit ).
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