C1541

DTC C1541 Power supply voltage abnormality (low voltage)

















CAUTION:

- If there is any problem in the CAN bus lines, an incorrect DTC may be set. Prior to this diagnosis, diagnose the CAN bus lines Scan Tool Testing and Procedures ).
- Whenever ECU is replaced, ensure that the CAN bus lines are normal.

OPERATION

- Power is supplied to the electric power steering-ECU from the battery or the ignition switch.

FUNCTION

- To control the steering gear and linkage assembly, the battery voltage is supplied to the electric power steering-ECU for energization.

TROUBLE JUDGMENT

Check Conditions

- The ETACS power supply circuit system DTC is not set.

Judgment Criterion

- The power supply voltage is less than 9.0 V.
- 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 electric power steering-ECU tapers the motor control and illuminates the electric power steering warning display, then sets the DTC 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 electric power steering-ECU, the ETACS-ECU and the fusible link or loose connector contact
- Open circuit between the body ground and the electric power steering-ECU or loose connector contact
- Malfunction of the ETACS-ECU
- Malfunction of the electric power steering-ECU

DIAGNOSIS

Required Special Tools:

- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)

STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.

Use scan tool to diagnose the CAN bus lines.

Q. Is the check result normal?

YES Go to Step 3.
NO Repair the CAN bus lines CAN Bus Diagnostics Chart).On completion, go to Step 2.
STEP 2. DTC recheck after resetting CAN bus lines

(1)Erase the DTC.

(2)Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.

(3)Check if the DTC is set.

Q. Is the DTC C1541 set?

YES Go to Step 3.
NO This diagnosis is complete.
STEP 3. Check the battery voltage.

Start the engine and measure the battery voltage Battery Test).

Q. Is the check result normal?

YES Go to Step 4.
NO Check the battery and repair if necessary Battery Charging, Battery Removal and Replacement).
Then go to Step 11.
STEP 4. Check the charging system.

Start the engine and measure the charging system Generator Output Line Voltage Drop Test).

Q. Is the check result normal?

YES Go to Step 5.
NO Check the charging system and repair if necessary Removal and Replacement). 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-113 and C-114 electric power steering-ECU connector
- C-309 and C-317 ETACS-ECU connector
- C-128 intermediate connector
- No.34 and 35 fusible link
- Body ground point

Q. Is the connectors and terminals in good condition?

YES Go to Step 6.
NO 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-140 electric power steering-ECU connector terminal No.11 and the fusible link No.35 for damage or other problem .

(2)Check the wiring harness between the C-141 electric power steering-ECU connector terminal No.1, the C-128 intermediate connector terminal No.19 and the C-317 ETACS-ECU connector terminal No.5 for damage or other problem .

(3)Check the wiring harness between the C-309 ETACS-ECU connector terminal No.1 and the fusible link No.34 for damage or other problem .

(4)Check the wiring harness between the C-140 electric power steering-ECU connector terminal No.12 and the body ground point for damage or other problem .

Q. Is the wiring harness in good condition?

YES Go to Step 7.
NO 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-309 ETACS-ECU connector terminal No.1 and the C-317 ETACS-ECU connector terminal No.5.
OK: Approximately system voltage

Q. Is the check result normal?

YES Go to Step 8.

NO Check the fusible link or the ETACS-ECU and repair if necessary Electronic Time and Alarm Control System (ETACS)-ECU Removal and Installation). Then go to Step 11.

STEP 8. Voltage measurement at the electric power steering-ECU connector









(1) Measure the electric power steering-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-141 electric power steering-ECU connector terminal No.1 and the C-140 electric power steering-ECU connector terminal No.12.
OK: Approximately system voltage
(4)Measure the voltage between the C-140 electric power steering-ECU connector terminals No.11 and No.12.
OK: Approximately system voltage

Q. Is the check result normal?

YES Go to Step 9.

NO Check the fusible link or the ETACS-ECU and repair if necessary Electronic Time and Alarm Control System (ETACS)-ECU Removal and Installation). Then go to Step 11.

STEP 9. Using scan tool MB991958, check the data list

Check the following data list Data List Reference Table.

- Item No. 22: Power relay voltage

- Item No. 23: Ignition voltage

Q. Is the check result normal?

YES Go to Step 11.
NO Go to Step 10.
STEP 10. Check whether the DTC is reset.

(1)Erase the DTC.

(2)Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.

(3)Check if the DTC is set.

Q. Is the DTC C1541 set?

YES Replace the electric power steering-ECU (Refer to Service and Repair). Then go to Step 11.
NO Intermittent malfunction How to Cope With Intermittent Malfunctions).
STEP 11. Check whether the DTC is reset.

(1)Erase the DTC.

(2)Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.

(3)Check if the DTC is set.

Q. Is the DTC C1541 set?

YES Return to Step 1.
NO This diagnosis is complete.