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- ASC-ECU contains the power supply circuit (terminal No. 1) for the pump motor.
The pump motor is energised by the motor switch, which is incorporated in ASC-ECU.
- The pump motor switch, which is incorporated in ASC-ECU, is always off unless the
motor solenoid valve check is activated when the vehicle is started.
- ASC-ECU activates the pump motor by turning on the ECU built-in pump motor switch.
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This diagnosis codes will be set under the cases below:
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- When the power supply voltage of the pump motor, which is not in operation,
is abnormally low for a prolonged period
- When the power supply voltage of the pump motor, which is not in operation, is abnormally
high for a prolonged period
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Current trouble
- Fusible link malfunction
- Damaged wiring harness and connectors
- Abnormality in battery or alternator
- ASC-ECU malfunction
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Past trouble
- Carry out diagnosis with particular emphasis on wiring harness and
connector failures between the power supply circuit (A-03 ASC-ECU connector terminal No. 1)
to the ASC-ECU motor and the earth circuit (A-03 ASC-ECU connector terminal No. 47). For diagnosis
procedures, refer to How to treat past trouble (GROUP 00 - How to Use Troubleshooting/Inspection
Service Points ).
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Use M.U.T.-III to diagnose the CAN bus lines.
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Q.
Is the check result normal?
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Repair the CAN bus lines (Refer to GROUP 54C - Troubleshooting ).
On completion, go to Step 2.
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Q.
Is the diagnosis code No. C2116 set?
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This diagnosis is complete.
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Q.
Is the check result normal?
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Replace the fusible link No. 26.
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Refer to GROUP 54A - Battery Test .
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Q.
Is the battery in good condition?
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Charge or replace the battery.
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Refer to GROUP 16 - Charging System .
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Q.
Is the charging system in good condition?
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Repair or replace the charging system component(s).
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(1)Disconnect the ASC-ECU connector, connect special tool ASC check harness (MB991997) to
the harness-side connector, and then measure the voltage at the special tool connector side.
note |
Do not connect the special tool ASC check harness (MB991997) to ASC-ECU.
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(2)Turn the ignition switch to the ON position. (3)Measure the voltage between the terminal No. 1 and the body earth. OK: Approximately battery voltage
Q.
Is the check result normal?
Go to Step 8.
Go to Step 7.
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Q.
Is the check result normal?
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The open or short circuit may be present in the solenoid valve power supply circuit.
Repair the wiring harness between the A-03 ASC-ECU connector terminal No. 1 and the fusible
link No. 26.
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NO : Repair the defective connector.
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(1)Disconnect the ASC-ECU connector, connect special tool ASC check harness (MB991997) to
the harness-side connector, and then measure the resistance at the special tool connector side.
note |
Do not connect the special tool ASC check harness (MB991997) to ASC-ECU.
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(2)Resistance between terminal 47 and body earth OK: Continuity exists (2 Ω or less)
Q.
Is the check result normal?
Go to Step 10.
Go to Step 9.
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Q.
Is the check result normal?
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An open circuit may be present in the earth circuit. Repair the wiring harness
between the A-03 ASC-ECU terminal No. 47 and the body earth.
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NO : Repair the defective connector.
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- Drive the vehicle at 20 km/h or more.
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Q.
Is the diagnosis code No. C2116 set?
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Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent
Malfunction ).
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