Diagnosis Item 4: Diagnose the terminator resistors.
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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![](../../../img/54/W7B54X004A00ENG.png)
![](../../../img/54/AC607562AE00ENG.png)
![](../../../img/54/AC607570AE00ENG.png)
![](../../../img/54/AC607564AE00ENG.png)
![](../../../img/54/AC607571AE00ENG.png)
FUNCTION
The resistance in the communication errors condition
cannot be measured by the CAN bus diagnostics, therefore, judge the terminator
resistor only when receiving the each ECU periodically sent data
normally.
TROUBLE JUDGEMENT CONDITIONS
The M.U.T.-III judges the trouble
when the periodically sent data from each ECU can be received normally but the
resistance value between CAN_H and CAN_L line is other than from
50 ohms to 70 ohms.
PROBABLE CAUSES
- Damaged harness wires and connectors
- Malfunction of the resistor <vehicles without ASTC> or
ASTC-ECU <vehicles with ASTC>
- Malfunction of the combination meter
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STEP 1. 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> Go to Step 2.
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<Not within 120 ± 20
Ω> Replace the resistor <vehicles without ASTC> or
ASTC-ECU <vehicles with ASTC>.
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STEP 2. Resistance measurement at D-04 combination meter
connector.
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caution |
A digital multimeter should be used. For details
refer to .
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(1)Remove the combination meter, and measure at the equipment
side.
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(2)Resistance between D-04 combination meter connector
terminal Nos.23 and 24 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> Repair the wiring harness between the ASTC-ECU connector and
the combination meter.
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<Not within 120 ± 20
Ω> Replace the combination meter.
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