Code No. C1861
Power supply low voltage
| caution |
- If there is any
problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis,
diagnose the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table
 ).
- Whenever ECU is replaced, ensure that the CAN bus lines are normal.
- When the hydraulic unit (integrated with ASC-ECU) is replaced, always carry out
the calibration of the steering wheel sensor and the G and yaw rate sensor (Refer to and ).
|
OPERATION
The ASC-ECU is energised by the ignition switch through the multi-purpose fuse at the
terminal IG1.
DIAGNOSIS CODE SET CONDITIONS
The ASC-ECU monitors the ASC-ECU power supply voltage sent from the battery. When the
voltage falls below a predetermined value, the ECU determines that the trouble occurs and sets
the diagnosis code.
PROBABLE CAUSES
Current trouble
- Battery failure
- Charging system failed
- Damaged harness wires and connectors
- Malfunction of ASC-ECU
Past trouble
- Carry out diagnosis with particular emphasis on connector(s) or wiring harness in
the power supply circuit (+BV and IG1 terminals) to the ASC-ECU. For diagnosis procedures,
refer to How to treat past trouble (GROUP 00 - How to Use Troubleshooting/Inspection
Service Points ).
|
|
STEP 1. M.U.T.-III CAN bus diagnosis
|
|
|
Use the M.U.T.-III to diagnose the CAN bus lines.
|
|
|
Q.
Is the check result normal?
|
|
|
 Go to Step 3.
|
|
|
|
|
|
 Repair the CAN bus line. (Refer to GROUP 54C - Troubleshooting .)
On completion, go to Step 2.
|
|
|
|
|
|
STEP 2. Diagnosis code recheck after resetting CAN bus lines
|
|
|
Q.
Is diagnosis code No. C1861 set?
|
|
|
Go to Step 3.
|
|
|
|
|
|
This diagnosis is complete.
|
|
|
|
|
|
STEP 3. Check the battery.
|
|
|
Refer to GROUP 54A - Battery Test .
|
|
|
Q.
Is the auxiliary battery normal?
|
|
|
Go to Step 4.
|
|
|
|
|
|
Charge or replace the battery. Then go to Step 11.
|
|
|
|
|
|
STEP 4. Check the charging system.
|
|
|
Refer to GROUP 16 - Charging System .
|
|
|
Q.
Is the charging system in good condition?
|
|
|
Go to Step 5.
|
|
|
|
|
|
Repair or replace the charging system component(s). Then go to Step 11.
|
|
|
|
|
|
STEP 5. Measure the resistance at the ASC-ECU connector.
|
|
|
(1)Connector check: the ASC-ECU connector, the fuses (relay box) and the fusible links
|
|
|
(2)Disconnect the ASC-ECU connector.
|
|
|
(3)Measure the resistance between +BV terminal and body earth.
OK: No continuity
|
|
|
Q.
Is the check result normal?
|
|
|
Go to Step 6.
|
|
|
|
|
|
The power supply circuit may be short. Repair the wiring harness wires or connectors
between the ACS-ECU connector +BV terminal and the fusible links, the fuse (relay box)
or the fusible links. Then go to Step 11.
|
|
|
|
|
|
STEP 6. Measure the resistance at the ASC-ECU connector.
|
|
|
(1)Connector check: the ASC-ECU connector and the junction block
|
|
|
(2)Disconnect the ASC-ECU connector.
|
|
|
(3)Measure the resistance between the IG1 terminal and body earth.
OK: No continuity
|
|
|
Q.
Is the check result normal?
|
|
|
Go to Step 7.
|
|
|
|
|
|
The power supply circuit may be short. Repair the wiring harness wires or connectors
between the ACS-ECU connector IG1 terminal and the junction block. Then go to Step 11.
|
|
|
|
|
|
STEP 7. Measure the voltage at the ASC-ECU connector.
|
|
|
(1)Disconnect the ASC-ECU connector.
|
|
|
(2)Measure the voltage between +BV terminal and body earth.
OK: Battery voltage
|
|
|
Q.
Is the check result normal?
|
|
|
Go to Step 8.
|
|
|
|
|
|
The power supply circuit may be open. Repair the wiring harness wires or connectors
between the ACS-ECU connector +BV terminal and the fusible links, the fuse (relay box)
or the fusible links. Then go to Step 11.
|
|
|
|
|
|
STEP 8. Measure the voltage at the ASC-ECU connector.
|
|
|
(1)Disconnect the ASC-ECU connector.
|
|
|
(3)Measure the voltage between the IG1 terminal and body earth.
OK: Battery voltage
|
|
|
Q.
Is the check result normal?
|
|
|
Go to Step 9.
|
|
|
|
|
|
The power supply circuit may be open. Repair the wiring harness wires or connectors
between the ACS-ECU connector IG1 terminal and the junction block. Then go to Step 11.
|
|
|
|
|
|
STEP 9. Measure the resistance at the ASC-ECU connector.
|
|
|
(1)Disconnect the ASC-ECU connector.
|
|
|
(2) Measure the resistance between the GND1 terminal and body earth as well as between
the GND2 terminal and body earth.
OK: Continuity exists (2 Ω or less).
|
|
|
Q.
Is the check result normal?
|
|
|
Go to Step 10.
|
|
|
|
|
|
The earth circuit may be open. Repair the wiring harness wires or connectors between
the ACS-ECU connector GND1 terminal and the fusible links as well as between the GND2 terminal
and the fusible links. Then go to Step 11.
|
|
|
|
|
|
STEP 10. Check whether the diagnosis code is set again.
|
|
|
Check again if the diagnosis code is set.
|
|
|
(1)Erase the set diagnosis code.
|
|
|
(2)Ignition switch: "LOCK" (OFF)
|
|
|
Q.
Is diagnosis code No. C1861 set?
|
|
|
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ).
Then go to Step 11.
|
|
|
|
|
|
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How
to Cope with Intermittent Malfunction ).
|
|
|
|
|
|
STEP 11. Check whether the diagnosis code is set again.
|
|
|
Check again if the diagnosis code is set.
|
|
|
(1)Erase the set diagnosis code.
|
|
|
(2)Ignition switch: "LOCK" (OFF)
|
|
|
Q.
Is diagnosis code No. C1861 set?
|
|
|
Return to Step 3.
|
|
|
|
|
|
This diagnosis is complete.
|
|
|
|