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DTC C1541 Power supply voltage too low
 
 
cautionWhenever ECU is replaced, ensure that the CAN bus lines are normal.
 
 
OPERATION
  • Power is supplied to the EPS-ECU from the fusible link (+B).
  • Power is supplied to the motor from the EPS-ECU.
 
 
 
FUNCTION
The EPS-ECU monitors the power supply voltage supplied from the fusible link (+B).
 
 
 
TROUBLE JUDGMENT
Check Conditions
  • Turn the ignition switch to the "ON" position (Engine running).
Judgment Criterion
  • When the +B voltage is less than 9 volts for more than 5 seconds.
  • When the motor power supply voltage is less than 5 volts.
    noteEPS-ECU voltage can be checked by M.U.T.-IIISE with the following items.
    • Item No.33: System1 PIG voltage
    • Item No.34: System2 PIG voltage
    • Item No.35: IG voltage
Fail Safe, Back Up Function
  • The EPS-ECU is in motor control output limit state, turns on the electric steering warning light, and sets DTC C1541.
 
 
 
TROUBLESHOOTING HINTS
  • Defective harness wire(s) or connector(s)
  • Defective battery (Insufficient charging, life, dirty / loose terminals)
  • Charging system failed
  • Malfunction of the EPS-ECU
 
 
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Battery check
Refer to GROUP 54A - Battery Test .
Is the battery in good condition?
Go to Step 2.
Replace the battery (Refer to GROUP 54A - Battery ).
 
STEP 2. Charging system check
Refer to GROUP 16 - On-vehicle Service/Generator Output Line Voltage Drop Test .
Is the charging system in good condition?
Go to Step 3.
Repair or replace the charging system component(s) (Refer to GROUP 16 - Generator ).
 
STEP 3. Check of open circuit in GND line between EPS-ECU connector and body ground.
notePrior to the wiring harness inspection, check intermediate connector and repair if necessary.
Is the check result normal?
Go to Step 4.
Repair the connector(s) or wiring harness.
 
STEP 4. Voltage measurement at the EPS-ECU connector (+B, GND terminal)
(1) Measure the EPS-ECU voltage without disconnecting the connector (by backprobing).
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between the EPS-ECU connector (+B terminal) and body ground.
OK: The voltage should measure approximately 12 volts (battery positive voltage)
Is the check result normal?
Go to Step 5.
Repair the connector(s) or wiring harness.
 
STEP 5. Using scan tool (M.U.T.-IIISE), check whether the DTC is set again.
(1) Erase the DTC.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3) Turn the ignition switch to the "ON" position (Engine running).
(4) Drive the vehicle.
(5) Check if the DTC is set.
Is the DTC set?
Replace the EPS motor (EPS-ECU) (Refer to ).
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunctions ).