Code No.C1541 Power supply voltage abnormality (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.

OPERATION

    Power is supplied to the EPS-ECU from the battery or the ignition switch.

FUNCTION

    To control the steering column shaft assembly, the battery voltage is supplied to the EPS-ECU for energisation.

TROUBLE JUDGEMENT
Check Conditions
    During engine running.
Judgement Criterion
    The power supply monitor voltage does not meet a predetermined voltage stored in the microcomputer, and the microcomputer determines that there is a problem in the power supply system.
Fail Safe, Back Up Function
    The EPS-ECU tapers the motor control and illuminates the electric power steering warning display, then sets the diagnosis code No. C1541.

PROBABLE CAUSES

  • Malfunction of CAN bus line
  • Defective battery
  • Charging system failed
  • Defective harness wire(s) or connector(s)

    • Short or open circuit between the EPS-ECU, the ETACS-ECU and the fusible link or loose connector contact
    • Open circuit between the body earth and the EPS-ECU or loose connector contact
  • Malfunction of the ETACS-ECU
  • Malfunction of the EPS-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
Use M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?
Go to Step 3.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ). On completion, go to Step 2.

STEP 2. Diagnosis code recheck after resetting CAN bus lines
(1)Erase the diagnosis code.
(2)Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.
(3)Check if the diagnosis code is set.

Q. Is the diagnosis code C1541 set?
Go to Step 3.
This diagnosis is complete.

STEP 3. Check the battery voltage.
Start the engine and measure the battery voltage (Refer to GROUP 54A - Battery ).

Q. Is the check result normal?
Go to Step 4.
Check the battery and repair if necessary (Refer to GROUP 54A - Battery , ). Then go to Step 11.

STEP 4. Check the charging system.
Start the engine and measure the charging system (Refer to GROUP 16 - On-vehicle Service/Alternator Output Line Voltage Drop Test )

Q. Is the check result normal?
Go to Step 5.
Check the charging system and repair if necessary (Refer to GROUP 16 - Alternator Assembly <1600 Petrol>, <1800, 2000 Petrol>, <Diesel>).Then go to Step 11.

STEP 5. Check the following connector.
Check the connectors below for improper engagement, terminal damage or terminal drawn in the connector case.

  • C-221 and C-222 EPS-ECU connector
  • C-408 and C-417 ETACS-ECU connector
  • C-127 intermediate connector
  • No.34 and No.35 fusible link <Petrol>
  • No.39 and No.44 fusible link <Diesel>
  • Body earth point

Q. Is the connectors and terminals in good condition?
Go to Step 6.
Repair the defective connector(s) or terminal(s). Then go to Step 11.

STEP 6. Wiring harness check
(1)Check the wiring harness between the C-222 EPS-ECU connector terminal No.11 and the fusible link No.35 <Petrol>, No.39 <Diesel> for damage or other problem.
(2)Check the wiring harness between the C-221 EPS-ECU connector terminal No.1, the C-127 intermediate connector terminal No.9 and the C-417 ETACS-ECU connector terminal No.5 for damage or other problem.
(3)Check the wiring harness between the C-408 ETACS-ECU connector terminal No.1 and the fusible link No.34 <Petrol>, No.44 <Diesel> for damage or other problem.
(4)Check the wiring harness between the C-222 EPS-ECU connector terminal No.12 and the body earth point for damage or other problem.

Q. Is the wiring harness in good condition?
Go to Step 7.
Repair the defective wiring harness. Then go to Step 11.

STEP 7. Voltage measurement at the ETACS-ECU connector
(1) Measure the ETACS-ECU voltage without disconnecting the connector (by backprobing).
(2)Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.
(3)Measure the voltage between the C-408 ETACS-ECU connector terminal No.1 and the C-417 ETACS-ECU connector terminal No.5.
OK: Battery positive voltage

Q. Is the check result normal?
Go to Step 8.
Check the fusible link or the ETACS-ECU and repair if necessary (Refer to GROUP 54A - ETACS ).Then go to Step 11.

STEP 8. Voltage measurement at the EPS-ECU connector
(1) Measure the EPS-ECU voltage without disconnecting the connector (by backprobing).
(2)Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.
(3)Measure the voltage between the C-221 EPS-ECU connector terminal No.1 and the C-222 EPS-ECU connector terminal No.12.
OK: Approximately system voltage
(4)Measure the voltage between the C-222 EPS-ECU connector terminals No.11 and No.12.
OK: Approximately system voltage

Q. Is the check result normal?
Go to Step 9.
Check the fusible link or the ETACS-ECU and repair if necessary (Refer to GROUP 54A - ETACS ).Then go to Step 11.

STEP 9. M.U.T.-III data list
Check the following data list .

  • Item No. 22: Power relay voltage

  • Item No. 23: Ignition voltage

Q. Is the check result normal?
Go to Step 11.
Go to Step 10.

STEP 10. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.
(3)Check if the diagnosis code is set.

Q. Is the diagnosis code C1541 set?
Replace the EPS-ECU (Refer to ).Then go to Step 11.
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunctions ).

STEP 11. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.
(3)Check if the diagnosis code is set.

Q. Is the diagnosis code C1541 set?
Return to Step 1.
This diagnosis is complete.